Source code for librosa.util.utils

#!/usr/bin/env python
# -*- coding: utf-8 -*-
"""Utility functions"""

import warnings
import scipy.ndimage
import scipy.sparse

import numpy as np
import numba
from numpy.lib.stride_tricks import as_strided

from .._cache import cache
from .exceptions import ParameterError

# Constrain STFT block sizes to 256 KB
MAX_MEM_BLOCK = 2 ** 8 * 2 ** 10

__all__ = [
    "MAX_MEM_BLOCK",
    "frame",
    "pad_center",
    "fix_length",
    "valid_audio",
    "valid_int",
    "valid_intervals",
    "fix_frames",
    "axis_sort",
    "localmax",
    "localmin",
    "normalize",
    "peak_pick",
    "sparsify_rows",
    "shear",
    "stack",
    "fill_off_diagonal",
    "index_to_slice",
    "sync",
    "softmask",
    "buf_to_float",
    "tiny",
    "cyclic_gradient",
    "dtype_r2c",
    "dtype_c2r",
]


[docs]def frame(x, frame_length, hop_length, axis=-1): """Slice a data array into (overlapping) frames. This implementation uses low-level stride manipulation to avoid making a copy of the data. The resulting frame representation is a new view of the same input data. However, if the input data is not contiguous in memory, a warning will be issued and the output will be a full copy, rather than a view of the input data. For example, a one-dimensional input ``x = [0, 1, 2, 3, 4, 5, 6]`` can be framed with frame length 3 and hop length 2 in two ways. The first (``axis=-1``), results in the array ``x_frames``:: [[0, 2, 4], [1, 3, 5], [2, 4, 6]] where each column ``x_frames[:, i]`` contains a contiguous slice of the input ``x[i * hop_length : i * hop_length + frame_length]``. The second way (``axis=0``) results in the array ``x_frames``:: [[0, 1, 2], [2, 3, 4], [4, 5, 6]] where each row ``x_frames[i]`` contains a contiguous slice of the input. This generalizes to higher dimensional inputs, as shown in the examples below. In general, the framing operation increments by 1 the number of dimensions, adding a new "frame axis" either to the end of the array (``axis=-1``) or the beginning of the array (``axis=0``). Parameters ---------- x : np.ndarray Array to frame frame_length : int > 0 [scalar] Length of the frame hop_length : int > 0 [scalar] Number of steps to advance between frames axis : 0 or -1 The axis along which to frame. If ``axis=-1`` (the default), then ``x`` is framed along its last dimension. ``x`` must be "F-contiguous" in this case. If ``axis=0``, then ``x`` is framed along its first dimension. ``x`` must be "C-contiguous" in this case. Returns ------- x_frames : np.ndarray [shape=(..., frame_length, N_FRAMES) or (N_FRAMES, frame_length, ...)] A framed view of ``x``, for example with ``axis=-1`` (framing on the last dimension):: x_frames[..., j] == x[..., j * hop_length : j * hop_length + frame_length] If ``axis=0`` (framing on the first dimension), then:: x_frames[j] = x[j * hop_length : j * hop_length + frame_length] Raises ------ ParameterError If ``x`` is not an `np.ndarray`. If ``x.shape[axis] < frame_length``, there is not enough data to fill one frame. If ``hop_length < 1``, frames cannot advance. If ``axis`` is not 0 or -1. Framing is only supported along the first or last axis. See Also -------- numpy.asfortranarray : Convert data to F-contiguous representation numpy.ascontiguousarray : Convert data to C-contiguous representation numpy.ndarray.flags : information about the memory layout of a numpy `ndarray`. Examples -------- Extract 2048-sample frames from monophonic signal with a hop of 64 samples per frame >>> y, sr = librosa.load(librosa.ex('trumpet')) >>> frames = librosa.util.frame(y, frame_length=2048, hop_length=64) >>> frames array([[-1.407e-03, -2.604e-02, ..., -1.795e-05, -8.108e-06], [-4.461e-04, -3.721e-02, ..., -1.573e-05, -1.652e-05], ..., [ 7.960e-02, -2.335e-01, ..., -6.815e-06, 1.266e-05], [ 9.568e-02, -1.252e-01, ..., 7.397e-06, -1.921e-05]], dtype=float32) >>> y.shape (117601,) >>> frames.shape (2048, 1806) Or frame along the first axis instead of the last: >>> frames = librosa.util.frame(y, frame_length=2048, hop_length=64, axis=0) >>> frames.shape (1806, 2048) Frame a stereo signal: >>> y, sr = librosa.load(librosa.ex('trumpet', hq=True), mono=False) >>> y.shape (2, 117601) >>> frames = librosa.util.frame(y, frame_length=2048, hop_length=64) (2, 2048, 1806) Carve an STFT into fixed-length patches of 32 frames with 50% overlap >>> y, sr = librosa.load(librosa.ex('trumpet')) >>> S = np.abs(librosa.stft(y)) >>> S.shape (1025, 230) >>> S_patch = librosa.util.frame(S, frame_length=32, hop_length=16) >>> S_patch.shape (1025, 32, 13) >>> # The first patch contains the first 32 frames of S >>> np.allclose(S_patch[:, :, 0], S[:, :32]) True >>> # The second patch contains frames 16 to 16+32=48, and so on >>> np.allclose(S_patch[:, :, 1], S[:, 16:48]) True """ if not isinstance(x, np.ndarray): raise ParameterError( "Input must be of type numpy.ndarray, " "given type(x)={}".format(type(x)) ) if x.shape[axis] < frame_length: raise ParameterError( "Input is too short (n={:d})" " for frame_length={:d}".format(x.shape[axis], frame_length) ) if hop_length < 1: raise ParameterError("Invalid hop_length: {:d}".format(hop_length)) if axis == -1 and not x.flags["F_CONTIGUOUS"]: warnings.warn( "librosa.util.frame called with axis={} " "on a non-contiguous input. This will result in a copy.".format(axis) ) x = np.asfortranarray(x) elif axis == 0 and not x.flags["C_CONTIGUOUS"]: warnings.warn( "librosa.util.frame called with axis={} " "on a non-contiguous input. This will result in a copy.".format(axis) ) x = np.ascontiguousarray(x) n_frames = 1 + (x.shape[axis] - frame_length) // hop_length strides = np.asarray(x.strides) new_stride = np.prod(strides[strides > 0] // x.itemsize) * x.itemsize if axis == -1: shape = list(x.shape)[:-1] + [frame_length, n_frames] strides = list(strides) + [hop_length * new_stride] elif axis == 0: shape = [n_frames, frame_length] + list(x.shape)[1:] strides = [hop_length * new_stride] + list(strides) else: raise ParameterError("Frame axis={} must be either 0 or -1".format(axis)) return as_strided(x, shape=shape, strides=strides)
[docs]@cache(level=20) def valid_audio(y, mono=True): """Determine whether a variable contains valid audio data. If ``mono=True``, then ``y`` is only considered valid if it has shape ``(N,)`` (number of samples). If ``mono=False``, then ``y`` may be either monophonic, or have shape ``(2, N)`` (stereo) or ``(K, N)`` for ``K>=2`` for general multi-channel. Parameters ---------- y : np.ndarray The input data to validate mono : bool Whether or not to require monophonic audio Returns ------- valid : bool True if all tests pass Raises ------ ParameterError In any of these cases: - ``type(y)`` is not ``np.ndarray`` - ``y.dtype`` is not floating-point - ``mono == True`` and ``y.ndim`` is not 1 - ``mono == False`` and ``y.ndim`` is not 1 or 2 - ``mono == False`` and ``y.ndim == 2`` but ``y.shape[0] == 1`` - ``np.isfinite(y).all()`` is False Notes ----- This function caches at level 20. Examples -------- >>> # By default, valid_audio allows only mono signals >>> filepath = librosa.ex('trumpet', hq=True) >>> y_mono, sr = librosa.load(filepath, mono=True) >>> y_stereo, _ = librosa.load(filepath, mono=False) >>> librosa.util.valid_audio(y_mono), librosa.util.valid_audio(y_stereo) True, False >>> # To allow stereo signals, set mono=False >>> librosa.util.valid_audio(y_stereo, mono=False) True See also -------- numpy.float32 """ if not isinstance(y, np.ndarray): raise ParameterError("Audio data must be of type numpy.ndarray") if not np.issubdtype(y.dtype, np.floating): raise ParameterError("Audio data must be floating-point") if mono and y.ndim != 1: raise ParameterError( "Invalid shape for monophonic audio: " "ndim={:d}, shape={}".format(y.ndim, y.shape) ) elif y.ndim > 2 or y.ndim == 0: raise ParameterError( "Audio data must have shape (samples,) or (channels, samples). " "Received shape={}".format(y.shape) ) elif y.ndim == 2 and y.shape[0] < 2: raise ParameterError( "Mono data must have shape (samples,). " "Received shape={}".format(y.shape) ) if not np.isfinite(y).all(): raise ParameterError("Audio buffer is not finite everywhere") return True
[docs]def valid_int(x, cast=None): """Ensure that an input value is integer-typed. This is primarily useful for ensuring integrable-valued array indices. Parameters ---------- x : number A scalar value to be cast to int cast : function [optional] A function to modify ``x`` before casting. Default: `np.floor` Returns ------- x_int : int ``x_int = int(cast(x))`` Raises ------ ParameterError If ``cast`` is provided and is not callable. """ if cast is None: cast = np.floor if not callable(cast): raise ParameterError("cast parameter must be callable") return int(cast(x))
[docs]def valid_intervals(intervals): """Ensure that an array is a valid representation of time intervals: - intervals.ndim == 2 - intervals.shape[1] == 2 - intervals[i, 0] <= intervals[i, 1] for all i Parameters ---------- intervals : np.ndarray [shape=(n, 2)] set of time intervals Returns ------- valid : bool True if ``intervals`` passes validation. """ if intervals.ndim != 2 or intervals.shape[-1] != 2: raise ParameterError("intervals must have shape (n, 2)") if np.any(intervals[:, 0] > intervals[:, 1]): raise ParameterError( "intervals={} must have non-negative durations".format(intervals) ) return True
[docs]def pad_center(data, size, axis=-1, **kwargs): """Pad an array to a target length along a target axis. This differs from `np.pad` by centering the data prior to padding, analogous to `str.center` Examples -------- >>> # Generate a vector >>> data = np.ones(5) >>> librosa.util.pad_center(data, 10, mode='constant') array([ 0., 0., 1., 1., 1., 1., 1., 0., 0., 0.]) >>> # Pad a matrix along its first dimension >>> data = np.ones((3, 5)) >>> librosa.util.pad_center(data, 7, axis=0) array([[ 0., 0., 0., 0., 0.], [ 0., 0., 0., 0., 0.], [ 1., 1., 1., 1., 1.], [ 1., 1., 1., 1., 1.], [ 1., 1., 1., 1., 1.], [ 0., 0., 0., 0., 0.], [ 0., 0., 0., 0., 0.]]) >>> # Or its second dimension >>> librosa.util.pad_center(data, 7, axis=1) array([[ 0., 1., 1., 1., 1., 1., 0.], [ 0., 1., 1., 1., 1., 1., 0.], [ 0., 1., 1., 1., 1., 1., 0.]]) Parameters ---------- data : np.ndarray Vector to be padded and centered size : int >= len(data) [scalar] Length to pad ``data`` axis : int Axis along which to pad and center the data kwargs : additional keyword arguments arguments passed to `np.pad` Returns ------- data_padded : np.ndarray ``data`` centered and padded to length ``size`` along the specified axis Raises ------ ParameterError If ``size < data.shape[axis]`` See Also -------- numpy.pad """ kwargs.setdefault("mode", "constant") n = data.shape[axis] lpad = int((size - n) // 2) lengths = [(0, 0)] * data.ndim lengths[axis] = (lpad, int(size - n - lpad)) if lpad < 0: raise ParameterError( ("Target size ({:d}) must be " "at least input size ({:d})").format(size, n) ) return np.pad(data, lengths, **kwargs)
[docs]def fix_length(data, size, axis=-1, **kwargs): """Fix the length an array ``data`` to exactly ``size`` along a target axis. If ``data.shape[axis] < n``, pad according to the provided kwargs. By default, ``data`` is padded with trailing zeros. Examples -------- >>> y = np.arange(7) >>> # Default: pad with zeros >>> librosa.util.fix_length(y, 10) array([0, 1, 2, 3, 4, 5, 6, 0, 0, 0]) >>> # Trim to a desired length >>> librosa.util.fix_length(y, 5) array([0, 1, 2, 3, 4]) >>> # Use edge-padding instead of zeros >>> librosa.util.fix_length(y, 10, mode='edge') array([0, 1, 2, 3, 4, 5, 6, 6, 6, 6]) Parameters ---------- data : np.ndarray array to be length-adjusted size : int >= 0 [scalar] desired length of the array axis : int, <= data.ndim axis along which to fix length kwargs : additional keyword arguments Parameters to ``np.pad`` Returns ------- data_fixed : np.ndarray [shape=data.shape] ``data`` either trimmed or padded to length ``size`` along the specified axis. See Also -------- numpy.pad """ kwargs.setdefault("mode", "constant") n = data.shape[axis] if n > size: slices = [slice(None)] * data.ndim slices[axis] = slice(0, size) return data[tuple(slices)] elif n < size: lengths = [(0, 0)] * data.ndim lengths[axis] = (0, size - n) return np.pad(data, lengths, **kwargs) return data
[docs]def fix_frames(frames, x_min=0, x_max=None, pad=True): """Fix a list of frames to lie within [x_min, x_max] Examples -------- >>> # Generate a list of frame indices >>> frames = np.arange(0, 1000.0, 50) >>> frames array([ 0., 50., 100., 150., 200., 250., 300., 350., 400., 450., 500., 550., 600., 650., 700., 750., 800., 850., 900., 950.]) >>> # Clip to span at most 250 >>> librosa.util.fix_frames(frames, x_max=250) array([ 0, 50, 100, 150, 200, 250]) >>> # Or pad to span up to 2500 >>> librosa.util.fix_frames(frames, x_max=2500) array([ 0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950, 2500]) >>> librosa.util.fix_frames(frames, x_max=2500, pad=False) array([ 0, 50, 100, 150, 200, 250, 300, 350, 400, 450, 500, 550, 600, 650, 700, 750, 800, 850, 900, 950]) >>> # Or starting away from zero >>> frames = np.arange(200, 500, 33) >>> frames array([200, 233, 266, 299, 332, 365, 398, 431, 464, 497]) >>> librosa.util.fix_frames(frames) array([ 0, 200, 233, 266, 299, 332, 365, 398, 431, 464, 497]) >>> librosa.util.fix_frames(frames, x_max=500) array([ 0, 200, 233, 266, 299, 332, 365, 398, 431, 464, 497, 500]) Parameters ---------- frames : np.ndarray [shape=(n_frames,)] List of non-negative frame indices x_min : int >= 0 or None Minimum allowed frame index x_max : int >= 0 or None Maximum allowed frame index pad : boolean If ``True``, then ``frames`` is expanded to span the full range ``[x_min, x_max]`` Returns ------- fixed_frames : np.ndarray [shape=(n_fixed_frames,), dtype=int] Fixed frame indices, flattened and sorted Raises ------ ParameterError If ``frames`` contains negative values """ frames = np.asarray(frames) if np.any(frames < 0): raise ParameterError("Negative frame index detected") if pad and (x_min is not None or x_max is not None): frames = np.clip(frames, x_min, x_max) if pad: pad_data = [] if x_min is not None: pad_data.append(x_min) if x_max is not None: pad_data.append(x_max) frames = np.concatenate((pad_data, frames)) if x_min is not None: frames = frames[frames >= x_min] if x_max is not None: frames = frames[frames <= x_max] return np.unique(frames).astype(int)
[docs]def axis_sort(S, axis=-1, index=False, value=None): """Sort an array along its rows or columns. Examples -------- Visualize NMF output for a spectrogram S >>> # Sort the columns of W by peak frequency bin >>> y, sr = librosa.load(librosa.ex('trumpet')) >>> S = np.abs(librosa.stft(y)) >>> W, H = librosa.decompose.decompose(S, n_components=64) >>> W_sort = librosa.util.axis_sort(W) Or sort by the lowest frequency bin >>> W_sort = librosa.util.axis_sort(W, value=np.argmin) Or sort the rows instead of the columns >>> W_sort_rows = librosa.util.axis_sort(W, axis=0) Get the sorting index also, and use it to permute the rows of H >>> W_sort, idx = librosa.util.axis_sort(W, index=True) >>> H_sort = H[idx, :] >>> import matplotlib.pyplot as plt >>> fig, ax = plt.subplots(nrows=2, ncols=2) >>> img_w = librosa.display.specshow(librosa.amplitude_to_db(W, ref=np.max), ... y_axis='log', ax=ax[0, 0]) >>> ax[0, 0].set(title='W') >>> ax[0, 0].label_outer() >>> img_act = librosa.display.specshow(H, x_axis='time', ax=ax[0, 1]) >>> ax[0, 1].set(title='H') >>> ax[0, 1].label_outer() >>> librosa.display.specshow(librosa.amplitude_to_db(W_sort, ... ref=np.max), ... y_axis='log', ax=ax[1, 0]) >>> ax[1, 0].set(title='W sorted') >>> librosa.display.specshow(H_sort, x_axis='time', ax=ax[1, 1]) >>> ax[1, 1].set(title='H sorted') >>> ax[1, 1].label_outer() >>> fig.colorbar(img_w, ax=ax[:, 0], orientation='horizontal') >>> fig.colorbar(img_act, ax=ax[:, 1], orientation='horizontal') Parameters ---------- S : np.ndarray [shape=(d, n)] Array to be sorted axis : int [scalar] The axis along which to compute the sorting values - ``axis=0`` to sort rows by peak column index - ``axis=1`` to sort columns by peak row index index : boolean [scalar] If true, returns the index array as well as the permuted data. value : function function to return the index corresponding to the sort order. Default: `np.argmax`. Returns ------- S_sort : np.ndarray [shape=(d, n)] ``S`` with the columns or rows permuted in sorting order idx : np.ndarray (optional) [shape=(d,) or (n,)] If ``index == True``, the sorting index used to permute ``S``. Length of ``idx`` corresponds to the selected ``axis``. Raises ------ ParameterError If ``S`` does not have exactly 2 dimensions (``S.ndim != 2``) """ if value is None: value = np.argmax if S.ndim != 2: raise ParameterError("axis_sort is only defined for 2D arrays") bin_idx = value(S, axis=np.mod(1 - axis, S.ndim)) idx = np.argsort(bin_idx) sort_slice = [slice(None)] * S.ndim sort_slice[axis] = idx if index: return S[tuple(sort_slice)], idx else: return S[tuple(sort_slice)]
[docs]@cache(level=40) def normalize(S, norm=np.inf, axis=0, threshold=None, fill=None): """Normalize an array along a chosen axis. Given a norm (described below) and a target axis, the input array is scaled so that:: norm(S, axis=axis) == 1 For example, ``axis=0`` normalizes each column of a 2-d array by aggregating over the rows (0-axis). Similarly, ``axis=1`` normalizes each row of a 2-d array. This function also supports thresholding small-norm slices: any slice (i.e., row or column) with norm below a specified ``threshold`` can be left un-normalized, set to all-zeros, or filled with uniform non-zero values that normalize to 1. Note: the semantics of this function differ from `scipy.linalg.norm` in two ways: multi-dimensional arrays are supported, but matrix-norms are not. Parameters ---------- S : np.ndarray The matrix to normalize norm : {np.inf, -np.inf, 0, float > 0, None} - `np.inf` : maximum absolute value - `-np.inf` : mininum absolute value - `0` : number of non-zeros (the support) - float : corresponding l_p norm See `scipy.linalg.norm` for details. - None : no normalization is performed axis : int [scalar] Axis along which to compute the norm. threshold : number > 0 [optional] Only the columns (or rows) with norm at least ``threshold`` are normalized. By default, the threshold is determined from the numerical precision of ``S.dtype``. fill : None or bool If None, then columns (or rows) with norm below ``threshold`` are left as is. If False, then columns (rows) with norm below ``threshold`` are set to 0. If True, then columns (rows) with norm below ``threshold`` are filled uniformly such that the corresponding norm is 1. .. note:: ``fill=True`` is incompatible with ``norm=0`` because no uniform vector exists with l0 "norm" equal to 1. Returns ------- S_norm : np.ndarray [shape=S.shape] Normalized array Raises ------ ParameterError If ``norm`` is not among the valid types defined above If ``S`` is not finite If ``fill=True`` and ``norm=0`` See Also -------- scipy.linalg.norm Notes ----- This function caches at level 40. Examples -------- >>> # Construct an example matrix >>> S = np.vander(np.arange(-2.0, 2.0)) >>> S array([[-8., 4., -2., 1.], [-1., 1., -1., 1.], [ 0., 0., 0., 1.], [ 1., 1., 1., 1.]]) >>> # Max (l-infinity)-normalize the columns >>> librosa.util.normalize(S) array([[-1. , 1. , -1. , 1. ], [-0.125, 0.25 , -0.5 , 1. ], [ 0. , 0. , 0. , 1. ], [ 0.125, 0.25 , 0.5 , 1. ]]) >>> # Max (l-infinity)-normalize the rows >>> librosa.util.normalize(S, axis=1) array([[-1. , 0.5 , -0.25 , 0.125], [-1. , 1. , -1. , 1. ], [ 0. , 0. , 0. , 1. ], [ 1. , 1. , 1. , 1. ]]) >>> # l1-normalize the columns >>> librosa.util.normalize(S, norm=1) array([[-0.8 , 0.667, -0.5 , 0.25 ], [-0.1 , 0.167, -0.25 , 0.25 ], [ 0. , 0. , 0. , 0.25 ], [ 0.1 , 0.167, 0.25 , 0.25 ]]) >>> # l2-normalize the columns >>> librosa.util.normalize(S, norm=2) array([[-0.985, 0.943, -0.816, 0.5 ], [-0.123, 0.236, -0.408, 0.5 ], [ 0. , 0. , 0. , 0.5 ], [ 0.123, 0.236, 0.408, 0.5 ]]) >>> # Thresholding and filling >>> S[:, -1] = 1e-308 >>> S array([[ -8.000e+000, 4.000e+000, -2.000e+000, 1.000e-308], [ -1.000e+000, 1.000e+000, -1.000e+000, 1.000e-308], [ 0.000e+000, 0.000e+000, 0.000e+000, 1.000e-308], [ 1.000e+000, 1.000e+000, 1.000e+000, 1.000e-308]]) >>> # By default, small-norm columns are left untouched >>> librosa.util.normalize(S) array([[ -1.000e+000, 1.000e+000, -1.000e+000, 1.000e-308], [ -1.250e-001, 2.500e-001, -5.000e-001, 1.000e-308], [ 0.000e+000, 0.000e+000, 0.000e+000, 1.000e-308], [ 1.250e-001, 2.500e-001, 5.000e-001, 1.000e-308]]) >>> # Small-norm columns can be zeroed out >>> librosa.util.normalize(S, fill=False) array([[-1. , 1. , -1. , 0. ], [-0.125, 0.25 , -0.5 , 0. ], [ 0. , 0. , 0. , 0. ], [ 0.125, 0.25 , 0.5 , 0. ]]) >>> # Or set to constant with unit-norm >>> librosa.util.normalize(S, fill=True) array([[-1. , 1. , -1. , 1. ], [-0.125, 0.25 , -0.5 , 1. ], [ 0. , 0. , 0. , 1. ], [ 0.125, 0.25 , 0.5 , 1. ]]) >>> # With an l1 norm instead of max-norm >>> librosa.util.normalize(S, norm=1, fill=True) array([[-0.8 , 0.667, -0.5 , 0.25 ], [-0.1 , 0.167, -0.25 , 0.25 ], [ 0. , 0. , 0. , 0.25 ], [ 0.1 , 0.167, 0.25 , 0.25 ]]) """ # Avoid div-by-zero if threshold is None: threshold = tiny(S) elif threshold <= 0: raise ParameterError( "threshold={} must be strictly " "positive".format(threshold) ) if fill not in [None, False, True]: raise ParameterError("fill={} must be None or boolean".format(fill)) if not np.all(np.isfinite(S)): raise ParameterError("Input must be finite") # All norms only depend on magnitude, let's do that first mag = np.abs(S).astype(np.float) # For max/min norms, filling with 1 works fill_norm = 1 if norm == np.inf: length = np.max(mag, axis=axis, keepdims=True) elif norm == -np.inf: length = np.min(mag, axis=axis, keepdims=True) elif norm == 0: if fill is True: raise ParameterError("Cannot normalize with norm=0 and fill=True") length = np.sum(mag > 0, axis=axis, keepdims=True, dtype=mag.dtype) elif np.issubdtype(type(norm), np.number) and norm > 0: length = np.sum(mag ** norm, axis=axis, keepdims=True) ** (1.0 / norm) if axis is None: fill_norm = mag.size ** (-1.0 / norm) else: fill_norm = mag.shape[axis] ** (-1.0 / norm) elif norm is None: return S else: raise ParameterError("Unsupported norm: {}".format(repr(norm))) # indices where norm is below the threshold small_idx = length < threshold Snorm = np.empty_like(S) if fill is None: # Leave small indices un-normalized length[small_idx] = 1.0 Snorm[:] = S / length elif fill: # If we have a non-zero fill value, we locate those entries by # doing a nan-divide. # If S was finite, then length is finite (except for small positions) length[small_idx] = np.nan Snorm[:] = S / length Snorm[np.isnan(Snorm)] = fill_norm else: # Set small values to zero by doing an inf-divide. # This is safe (by IEEE-754) as long as S is finite. length[small_idx] = np.inf Snorm[:] = S / length return Snorm
[docs]def localmax(x, axis=0): """Find local maxima in an array An element ``x[i]`` is considered a local maximum if the following conditions are met: - ``x[i] > x[i-1]`` - ``x[i] >= x[i+1]`` Note that the first condition is strict, and that the first element ``x[0]`` will never be considered as a local maximum. Examples -------- >>> x = np.array([1, 0, 1, 2, -1, 0, -2, 1]) >>> librosa.util.localmax(x) array([False, False, False, True, False, True, False, True], dtype=bool) >>> # Two-dimensional example >>> x = np.array([[1,0,1], [2, -1, 0], [2, 1, 3]]) >>> librosa.util.localmax(x, axis=0) array([[False, False, False], [ True, False, False], [False, True, True]], dtype=bool) >>> librosa.util.localmax(x, axis=1) array([[False, False, True], [False, False, True], [False, False, True]], dtype=bool) Parameters ---------- x : np.ndarray [shape=(d1,d2,...)] input vector or array axis : int axis along which to compute local maximality Returns ------- m : np.ndarray [shape=x.shape, dtype=bool] indicator array of local maximality along ``axis`` See Also -------- localmin """ paddings = [(0, 0)] * x.ndim paddings[axis] = (1, 1) x_pad = np.pad(x, paddings, mode="edge") inds1 = [slice(None)] * x.ndim inds1[axis] = slice(0, -2) inds2 = [slice(None)] * x.ndim inds2[axis] = slice(2, x_pad.shape[axis]) return (x > x_pad[tuple(inds1)]) & (x >= x_pad[tuple(inds2)])
[docs]def localmin(x, axis=0): """Find local minima in an array An element ``x[i]`` is considered a local minimum if the following conditions are met: - ``x[i] < x[i-1]`` - ``x[i] <= x[i+1]`` Note that the first condition is strict, and that the first element ``x[0]`` will never be considered as a local minimum. Examples -------- >>> x = np.array([1, 0, 1, 2, -1, 0, -2, 1]) >>> librosa.util.localmin(x) array([False, True, False, False, True, False, True, False]) >>> # Two-dimensional example >>> x = np.array([[1,0,1], [2, -1, 0], [2, 1, 3]]) >>> librosa.util.localmin(x, axis=0) array([[False, False, False], [False, True, True], [False, False, False]]) >>> librosa.util.localmin(x, axis=1) array([[False, True, False], [False, True, False], [False, True, False]]) Parameters ---------- x : np.ndarray [shape=(d1,d2,...)] input vector or array axis : int axis along which to compute local minimality Returns ------- m : np.ndarray [shape=x.shape, dtype=bool] indicator array of local minimality along ``axis`` See Also -------- localmax """ paddings = [(0, 0)] * x.ndim paddings[axis] = (1, 1) x_pad = np.pad(x, paddings, mode="edge") inds1 = [slice(None)] * x.ndim inds1[axis] = slice(0, -2) inds2 = [slice(None)] * x.ndim inds2[axis] = slice(2, x_pad.shape[axis]) return (x < x_pad[tuple(inds1)]) & (x <= x_pad[tuple(inds2)])
[docs]def peak_pick(x, pre_max, post_max, pre_avg, post_avg, delta, wait): """Uses a flexible heuristic to pick peaks in a signal. A sample n is selected as an peak if the corresponding ``x[n]`` fulfills the following three conditions: 1. ``x[n] == max(x[n - pre_max:n + post_max])`` 2. ``x[n] >= mean(x[n - pre_avg:n + post_avg]) + delta`` 3. ``n - previous_n > wait`` where ``previous_n`` is the last sample picked as a peak (greedily). This implementation is based on [#]_ and [#]_. .. [#] Boeck, Sebastian, Florian Krebs, and Markus Schedl. "Evaluating the Online Capabilities of Onset Detection Methods." ISMIR. 2012. .. [#] https://github.com/CPJKU/onset_detection/blob/master/onset_program.py Parameters ---------- x : np.ndarray [shape=(n,)] input signal to peak picks from pre_max : int >= 0 [scalar] number of samples before ``n`` over which max is computed post_max : int >= 1 [scalar] number of samples after ``n`` over which max is computed pre_avg : int >= 0 [scalar] number of samples before ``n`` over which mean is computed post_avg : int >= 1 [scalar] number of samples after ``n`` over which mean is computed delta : float >= 0 [scalar] threshold offset for mean wait : int >= 0 [scalar] number of samples to wait after picking a peak Returns ------- peaks : np.ndarray [shape=(n_peaks,), dtype=int] indices of peaks in ``x`` Raises ------ ParameterError If any input lies outside its defined range Examples -------- >>> y, sr = librosa.load(librosa.ex('trumpet')) >>> onset_env = librosa.onset.onset_strength(y=y, sr=sr, ... hop_length=512, ... aggregate=np.median) >>> peaks = librosa.util.peak_pick(onset_env, 3, 3, 3, 5, 0.5, 10) >>> peaks array([ 3, 27, 40, 61, 72, 88, 103]) >>> import matplotlib.pyplot as plt >>> times = librosa.times_like(onset_env, sr=sr, hop_length=512) >>> fig, ax = plt.subplots(nrows=2, sharex=True) >>> D = np.abs(librosa.stft(y)) >>> librosa.display.specshow(librosa.amplitude_to_db(D, ref=np.max), ... y_axis='log', x_axis='time', ax=ax[1]) >>> ax[0].plot(times, onset_env, alpha=0.8, label='Onset strength') >>> ax[0].vlines(times[peaks], 0, ... onset_env.max(), color='r', alpha=0.8, ... label='Selected peaks') >>> ax[0].legend(frameon=True, framealpha=0.8) >>> ax[0].label_outer() """ if pre_max < 0: raise ParameterError("pre_max must be non-negative") if pre_avg < 0: raise ParameterError("pre_avg must be non-negative") if delta < 0: raise ParameterError("delta must be non-negative") if wait < 0: raise ParameterError("wait must be non-negative") if post_max <= 0: raise ParameterError("post_max must be positive") if post_avg <= 0: raise ParameterError("post_avg must be positive") if x.ndim != 1: raise ParameterError("input array must be one-dimensional") # Ensure valid index types pre_max = valid_int(pre_max, cast=np.ceil) post_max = valid_int(post_max, cast=np.ceil) pre_avg = valid_int(pre_avg, cast=np.ceil) post_avg = valid_int(post_avg, cast=np.ceil) wait = valid_int(wait, cast=np.ceil) # Get the maximum of the signal over a sliding window max_length = pre_max + post_max max_origin = np.ceil(0.5 * (pre_max - post_max)) # Using mode='constant' and cval=x.min() effectively truncates # the sliding window at the boundaries mov_max = scipy.ndimage.filters.maximum_filter1d( x, int(max_length), mode="constant", origin=int(max_origin), cval=x.min() ) # Get the mean of the signal over a sliding window avg_length = pre_avg + post_avg avg_origin = np.ceil(0.5 * (pre_avg - post_avg)) # Here, there is no mode which results in the behavior we want, # so we'll correct below. mov_avg = scipy.ndimage.filters.uniform_filter1d( x, int(avg_length), mode="nearest", origin=int(avg_origin) ) # Correct sliding average at the beginning n = 0 # Only need to correct in the range where the window needs to be truncated while n - pre_avg < 0 and n < x.shape[0]: # This just explicitly does mean(x[n - pre_avg:n + post_avg]) # with truncation start = n - pre_avg start = start if start > 0 else 0 mov_avg[n] = np.mean(x[start : n + post_avg]) n += 1 # Correct sliding average at the end n = x.shape[0] - post_avg # When post_avg > x.shape[0] (weird case), reset to 0 n = n if n > 0 else 0 while n < x.shape[0]: start = n - pre_avg start = start if start > 0 else 0 mov_avg[n] = np.mean(x[start : n + post_avg]) n += 1 # First mask out all entries not equal to the local max detections = x * (x == mov_max) # Then mask out all entries less than the thresholded average detections = detections * (detections >= (mov_avg + delta)) # Initialize peaks array, to be filled greedily peaks = [] # Remove onsets which are close together in time last_onset = -np.inf for i in np.nonzero(detections)[0]: # Only report an onset if the "wait" samples was reported if i > last_onset + wait: peaks.append(i) # Save last reported onset last_onset = i return np.array(peaks)
[docs]@cache(level=40) def sparsify_rows(x, quantile=0.01, dtype=None): """Return a row-sparse matrix approximating the input Parameters ---------- x : np.ndarray [ndim <= 2] The input matrix to sparsify. quantile : float in [0, 1.0) Percentage of magnitude to discard in each row of ``x`` dtype : np.dtype, optional The dtype of the output array. If not provided, then ``x.dtype`` will be used. Returns ------- x_sparse : ``scipy.sparse.csr_matrix`` [shape=x.shape] Row-sparsified approximation of ``x`` If ``x.ndim == 1``, then ``x`` is interpreted as a row vector, and ``x_sparse.shape == (1, len(x))``. Raises ------ ParameterError If ``x.ndim > 2`` If ``quantile`` lies outside ``[0, 1.0)`` Notes ----- This function caches at level 40. Examples -------- >>> # Construct a Hann window to sparsify >>> x = scipy.signal.hann(32) >>> x array([ 0. , 0.01 , 0.041, 0.09 , 0.156, 0.236, 0.326, 0.424, 0.525, 0.625, 0.72 , 0.806, 0.879, 0.937, 0.977, 0.997, 0.997, 0.977, 0.937, 0.879, 0.806, 0.72 , 0.625, 0.525, 0.424, 0.326, 0.236, 0.156, 0.09 , 0.041, 0.01 , 0. ]) >>> # Discard the bottom percentile >>> x_sparse = librosa.util.sparsify_rows(x, quantile=0.01) >>> x_sparse <1x32 sparse matrix of type '<type 'numpy.float64'>' with 26 stored elements in Compressed Sparse Row format> >>> x_sparse.todense() matrix([[ 0. , 0. , 0. , 0.09 , 0.156, 0.236, 0.326, 0.424, 0.525, 0.625, 0.72 , 0.806, 0.879, 0.937, 0.977, 0.997, 0.997, 0.977, 0.937, 0.879, 0.806, 0.72 , 0.625, 0.525, 0.424, 0.326, 0.236, 0.156, 0.09 , 0. , 0. , 0. ]]) >>> # Discard up to the bottom 10th percentile >>> x_sparse = librosa.util.sparsify_rows(x, quantile=0.1) >>> x_sparse <1x32 sparse matrix of type '<type 'numpy.float64'>' with 20 stored elements in Compressed Sparse Row format> >>> x_sparse.todense() matrix([[ 0. , 0. , 0. , 0. , 0. , 0. , 0.326, 0.424, 0.525, 0.625, 0.72 , 0.806, 0.879, 0.937, 0.977, 0.997, 0.997, 0.977, 0.937, 0.879, 0.806, 0.72 , 0.625, 0.525, 0.424, 0.326, 0. , 0. , 0. , 0. , 0. , 0. ]]) """ if x.ndim == 1: x = x.reshape((1, -1)) elif x.ndim > 2: raise ParameterError( "Input must have 2 or fewer dimensions. " "Provided x.shape={}.".format(x.shape) ) if not 0.0 <= quantile < 1: raise ParameterError("Invalid quantile {:.2f}".format(quantile)) if dtype is None: dtype = x.dtype x_sparse = scipy.sparse.lil_matrix(x.shape, dtype=dtype) mags = np.abs(x) norms = np.sum(mags, axis=1, keepdims=True) mag_sort = np.sort(mags, axis=1) cumulative_mag = np.cumsum(mag_sort / norms, axis=1) threshold_idx = np.argmin(cumulative_mag < quantile, axis=1) for i, j in enumerate(threshold_idx): idx = np.where(mags[i] >= mag_sort[i, j]) x_sparse[i, idx] = x[i, idx] return x_sparse.tocsr()
[docs]def buf_to_float(x, n_bytes=2, dtype=np.float32): """Convert an integer buffer to floating point values. This is primarily useful when loading integer-valued wav data into numpy arrays. Parameters ---------- x : np.ndarray [dtype=int] The integer-valued data buffer n_bytes : int [1, 2, 4] The number of bytes per sample in ``x`` dtype : numeric type The target output type (default: 32-bit float) Returns ------- x_float : np.ndarray [dtype=float] The input data buffer cast to floating point """ # Invert the scale of the data scale = 1.0 / float(1 << ((8 * n_bytes) - 1)) # Construct the format string fmt = "<i{:d}".format(n_bytes) # Rescale and format the data buffer return scale * np.frombuffer(x, fmt).astype(dtype)
[docs]def index_to_slice(idx, idx_min=None, idx_max=None, step=None, pad=True): """Generate a slice array from an index array. Parameters ---------- idx : list-like Array of index boundaries idx_min, idx_max : None or int Minimum and maximum allowed indices step : None or int Step size for each slice. If `None`, then the default step of 1 is used. pad : boolean If `True`, pad ``idx`` to span the range ``idx_min:idx_max``. Returns ------- slices : list of slice ``slices[i] = slice(idx[i], idx[i+1], step)`` Additional slice objects may be added at the beginning or end, depending on whether ``pad==True`` and the supplied values for ``idx_min`` and ``idx_max``. See Also -------- fix_frames Examples -------- >>> # Generate slices from spaced indices >>> librosa.util.index_to_slice(np.arange(20, 100, 15)) [slice(20, 35, None), slice(35, 50, None), slice(50, 65, None), slice(65, 80, None), slice(80, 95, None)] >>> # Pad to span the range (0, 100) >>> librosa.util.index_to_slice(np.arange(20, 100, 15), ... idx_min=0, idx_max=100) [slice(0, 20, None), slice(20, 35, None), slice(35, 50, None), slice(50, 65, None), slice(65, 80, None), slice(80, 95, None), slice(95, 100, None)] >>> # Use a step of 5 for each slice >>> librosa.util.index_to_slice(np.arange(20, 100, 15), ... idx_min=0, idx_max=100, step=5) [slice(0, 20, 5), slice(20, 35, 5), slice(35, 50, 5), slice(50, 65, 5), slice(65, 80, 5), slice(80, 95, 5), slice(95, 100, 5)] """ # First, normalize the index set idx_fixed = fix_frames(idx, idx_min, idx_max, pad=pad) # Now convert the indices to slices return [slice(start, end, step) for (start, end) in zip(idx_fixed, idx_fixed[1:])]
[docs]@cache(level=40) def sync(data, idx, aggregate=None, pad=True, axis=-1): """Synchronous aggregation of a multi-dimensional array between boundaries .. note:: In order to ensure total coverage, boundary points may be added to ``idx``. If synchronizing a feature matrix against beat tracker output, ensure that frame index numbers are properly aligned and use the same hop length. Parameters ---------- data : np.ndarray multi-dimensional array of features idx : iterable of ints or slices Either an ordered array of boundary indices, or an iterable collection of slice objects. aggregate : function aggregation function (default: `np.mean`) pad : boolean If `True`, ``idx`` is padded to span the full range ``[0, data.shape[axis]]`` axis : int The axis along which to aggregate data Returns ------- data_sync : ndarray ``data_sync`` will have the same dimension as ``data``, except that the ``axis`` coordinate will be reduced according to ``idx``. For example, a 2-dimensional ``data`` with ``axis=-1`` should satisfy:: data_sync[:, i] = aggregate(data[:, idx[i-1]:idx[i]], axis=-1) Raises ------ ParameterError If the index set is not of consistent type (all slices or all integers) Notes ----- This function caches at level 40. Examples -------- Beat-synchronous CQT spectra >>> y, sr = librosa.load(librosa.ex('choice')) >>> tempo, beats = librosa.beat.beat_track(y=y, sr=sr, trim=False) >>> C = np.abs(librosa.cqt(y=y, sr=sr)) >>> beats = librosa.util.fix_frames(beats, x_max=C.shape[1]) By default, use mean aggregation >>> C_avg = librosa.util.sync(C, beats) Use median-aggregation instead of mean >>> C_med = librosa.util.sync(C, beats, ... aggregate=np.median) Or sub-beat synchronization >>> sub_beats = librosa.segment.subsegment(C, beats) >>> sub_beats = librosa.util.fix_frames(sub_beats, x_max=C.shape[1]) >>> C_med_sub = librosa.util.sync(C, sub_beats, aggregate=np.median) Plot the results >>> import matplotlib.pyplot as plt >>> beat_t = librosa.frames_to_time(beats, sr=sr) >>> subbeat_t = librosa.frames_to_time(sub_beats, sr=sr) >>> fig, ax = plt.subplots(nrows=3, sharex=True, sharey=True) >>> librosa.display.specshow(librosa.amplitude_to_db(C, ... ref=np.max), ... x_axis='time', ax=ax[0]) >>> ax[0].set(title='CQT power, shape={}'.format(C.shape)) >>> ax[0].label_outer() >>> librosa.display.specshow(librosa.amplitude_to_db(C_med, ... ref=np.max), ... x_coords=beat_t, x_axis='time', ax=ax[1]) >>> ax[1].set(title='Beat synchronous CQT power, ' ... 'shape={}'.format(C_med.shape)) >>> ax[1].label_outer() >>> librosa.display.specshow(librosa.amplitude_to_db(C_med_sub, ... ref=np.max), ... x_coords=subbeat_t, x_axis='time', ax=ax[2]) >>> ax[2].set(title='Sub-beat synchronous CQT power, ' ... 'shape={}'.format(C_med_sub.shape)) """ if aggregate is None: aggregate = np.mean shape = list(data.shape) if np.all([isinstance(_, slice) for _ in idx]): slices = idx elif np.all([np.issubdtype(type(_), np.integer) for _ in idx]): slices = index_to_slice(np.asarray(idx), 0, shape[axis], pad=pad) else: raise ParameterError("Invalid index set: {}".format(idx)) agg_shape = list(shape) agg_shape[axis] = len(slices) data_agg = np.empty( agg_shape, order="F" if np.isfortran(data) else "C", dtype=data.dtype ) idx_in = [slice(None)] * data.ndim idx_agg = [slice(None)] * data_agg.ndim for (i, segment) in enumerate(slices): idx_in[axis] = segment idx_agg[axis] = i data_agg[tuple(idx_agg)] = aggregate(data[tuple(idx_in)], axis=axis) return data_agg
[docs]def softmask(X, X_ref, power=1, split_zeros=False): """Robustly compute a soft-mask operation. ``M = X**power / (X**power + X_ref**power)`` Parameters ---------- X : np.ndarray The (non-negative) input array corresponding to the positive mask elements X_ref : np.ndarray The (non-negative) array of reference or background elements. Must have the same shape as ``X``. power : number > 0 or np.inf If finite, returns the soft mask computed in a numerically stable way If infinite, returns a hard (binary) mask equivalent to ``X > X_ref``. Note: for hard masks, ties are always broken in favor of ``X_ref`` (``mask=0``). split_zeros : bool If `True`, entries where ``X`` and ``X_ref`` are both small (close to 0) will receive mask values of 0.5. Otherwise, the mask is set to 0 for these entries. Returns ------- mask : np.ndarray, shape=X.shape The output mask array Raises ------ ParameterError If ``X`` and ``X_ref`` have different shapes. If ``X`` or ``X_ref`` are negative anywhere If ``power <= 0`` Examples -------- >>> X = 2 * np.ones((3, 3)) >>> X_ref = np.vander(np.arange(3.0)) >>> X array([[ 2., 2., 2.], [ 2., 2., 2.], [ 2., 2., 2.]]) >>> X_ref array([[ 0., 0., 1.], [ 1., 1., 1.], [ 4., 2., 1.]]) >>> librosa.util.softmask(X, X_ref, power=1) array([[ 1. , 1. , 0.667], [ 0.667, 0.667, 0.667], [ 0.333, 0.5 , 0.667]]) >>> librosa.util.softmask(X_ref, X, power=1) array([[ 0. , 0. , 0.333], [ 0.333, 0.333, 0.333], [ 0.667, 0.5 , 0.333]]) >>> librosa.util.softmask(X, X_ref, power=2) array([[ 1. , 1. , 0.8], [ 0.8, 0.8, 0.8], [ 0.2, 0.5, 0.8]]) >>> librosa.util.softmask(X, X_ref, power=4) array([[ 1. , 1. , 0.941], [ 0.941, 0.941, 0.941], [ 0.059, 0.5 , 0.941]]) >>> librosa.util.softmask(X, X_ref, power=100) array([[ 1.000e+00, 1.000e+00, 1.000e+00], [ 1.000e+00, 1.000e+00, 1.000e+00], [ 7.889e-31, 5.000e-01, 1.000e+00]]) >>> librosa.util.softmask(X, X_ref, power=np.inf) array([[ True, True, True], [ True, True, True], [False, False, True]], dtype=bool) """ if X.shape != X_ref.shape: raise ParameterError("Shape mismatch: {}!={}".format(X.shape, X_ref.shape)) if np.any(X < 0) or np.any(X_ref < 0): raise ParameterError("X and X_ref must be non-negative") if power <= 0: raise ParameterError("power must be strictly positive") # We're working with ints, cast to float. dtype = X.dtype if not np.issubdtype(dtype, np.floating): dtype = np.float32 # Re-scale the input arrays relative to the larger value Z = np.maximum(X, X_ref).astype(dtype) bad_idx = Z < np.finfo(dtype).tiny Z[bad_idx] = 1 # For finite power, compute the softmask if np.isfinite(power): mask = (X / Z) ** power ref_mask = (X_ref / Z) ** power good_idx = ~bad_idx mask[good_idx] /= mask[good_idx] + ref_mask[good_idx] # Wherever energy is below energy in both inputs, split the mask if split_zeros: mask[bad_idx] = 0.5 else: mask[bad_idx] = 0.0 else: # Otherwise, compute the hard mask mask = X > X_ref return mask
[docs]def tiny(x): """Compute the tiny-value corresponding to an input's data type. This is the smallest "usable" number representable in ``x.dtype`` (e.g., float32). This is primarily useful for determining a threshold for numerical underflow in division or multiplication operations. Parameters ---------- x : number or np.ndarray The array to compute the tiny-value for. All that matters here is ``x.dtype`` Returns ------- tiny_value : float The smallest positive usable number for the type of ``x``. If ``x`` is integer-typed, then the tiny value for ``np.float32`` is returned instead. See Also -------- numpy.finfo Examples -------- For a standard double-precision floating point number: >>> librosa.util.tiny(1.0) 2.2250738585072014e-308 Or explicitly as double-precision >>> librosa.util.tiny(np.asarray(1e-5, dtype=np.float64)) 2.2250738585072014e-308 Or complex numbers >>> librosa.util.tiny(1j) 2.2250738585072014e-308 Single-precision floating point: >>> librosa.util.tiny(np.asarray(1e-5, dtype=np.float32)) 1.1754944e-38 Integer >>> librosa.util.tiny(5) 1.1754944e-38 """ # Make sure we have an array view x = np.asarray(x) # Only floating types generate a tiny if np.issubdtype(x.dtype, np.floating) or np.issubdtype( x.dtype, np.complexfloating ): dtype = x.dtype else: dtype = np.float32 return np.finfo(dtype).tiny
def fill_off_diagonal(x, radius, value=0): """Sets all cells of a matrix to a given ``value`` if they lie outside a constraint region. In this case, the constraint region is the Sakoe-Chiba band which runs with a fixed ``radius`` along the main diagonal. When ``x.shape[0] != x.shape[1]``, the radius will be expanded so that ``x[-1, -1] = 1`` always. ``x`` will be modified in place. Parameters ---------- x : np.ndarray [shape=(N, M)] Input matrix, will be modified in place. radius : float The band radius (1/2 of the width) will be ``int(radius*min(x.shape))`` value : int ``x[n, m] = value`` when ``(n, m)`` lies outside the band. Examples -------- >>> x = np.ones((8, 8)) >>> librosa.util.fill_off_diagonal(x, 0.25) >>> x array([[1, 1, 0, 0, 0, 0, 0, 0], [1, 1, 1, 0, 0, 0, 0, 0], [0, 1, 1, 1, 0, 0, 0, 0], [0, 0, 1, 1, 1, 0, 0, 0], [0, 0, 0, 1, 1, 1, 0, 0], [0, 0, 0, 0, 1, 1, 1, 0], [0, 0, 0, 0, 0, 1, 1, 1], [0, 0, 0, 0, 0, 0, 1, 1]]) >>> x = np.ones((8, 12)) >>> librosa.util.fill_off_diagonal(x, 0.25) >>> x array([[1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0], [1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0], [0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0], [0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0], [0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0, 0], [0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1, 0], [0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1], [0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1]]) """ nx, ny = x.shape # Calculate the radius in indices, rather than proportion radius = np.round(radius * np.min(x.shape)) nx, ny = x.shape offset = np.abs((x.shape[0] - x.shape[1])) if nx < ny: idx_u = np.triu_indices_from(x, k=radius + offset) idx_l = np.tril_indices_from(x, k=-radius) else: idx_u = np.triu_indices_from(x, k=radius) idx_l = np.tril_indices_from(x, k=-radius - offset) # modify input matrix x[idx_u] = value x[idx_l] = value
[docs]def cyclic_gradient(data, edge_order=1, axis=-1): """Estimate the gradient of a function over a uniformly sampled, periodic domain. This is essentially the same as `np.gradient`, except that edge effects are handled by wrapping the observations (i.e. assuming periodicity) rather than extrapolation. Parameters ---------- data : np.ndarray The function values observed at uniformly spaced positions on a periodic domain edge_order: {1, 2} The order of the difference approximation used for estimating the gradient axis : int The axis along which gradients are calculated. Returns ------- grad : np.ndarray like ``data`` The gradient of ``data`` taken along the specified axis. See Also -------- numpy.gradient Examples -------- This example estimates the gradient of cosine (-sine) from 64 samples using direct (aperiodic) and periodic gradient calculation. >>> import matplotlib.pyplot as plt >>> x = 2 * np.pi * np.linspace(0, 1, num=64, endpoint=False) >>> y = np.cos(x) >>> grad = np.gradient(y) >>> cyclic_grad = librosa.util.cyclic_gradient(y) >>> true_grad = -np.sin(x) * 2 * np.pi / len(x) >>> fig, ax = plt.subplots() >>> ax.plot(x, true_grad, label='True gradient', linewidth=5, ... alpha=0.35) >>> ax.plot(x, cyclic_grad, label='cyclic_gradient') >>> ax.plot(x, grad, label='np.gradient', linestyle=':') >>> ax.legend() >>> # Zoom into the first part of the sequence >>> ax.set(xlim=[0, np.pi/16], ylim=[-0.025, 0.025]) """ # Wrap-pad the data along the target axis by `edge_order` on each side padding = [(0, 0)] * data.ndim padding[axis] = (edge_order, edge_order) data_pad = np.pad(data, padding, mode="wrap") # Compute the gradient grad = np.gradient(data_pad, edge_order=edge_order, axis=axis) # Remove the padding slices = [slice(None)] * data.ndim slices[axis] = slice(edge_order, -edge_order) return grad[tuple(slices)]
@numba.jit(nopython=True, cache=True) def __shear_dense(X, factor=+1, axis=-1): """Numba-accelerated shear for dense (ndarray) arrays""" if axis == 0: X = X.T X_shear = np.empty_like(X) for i in range(X.shape[1]): X_shear[:, i] = np.roll(X[:, i], factor * i) if axis == 0: X_shear = X_shear.T return X_shear def __shear_sparse(X, factor=+1, axis=-1): """Fast shearing for sparse matrices Shearing is performed using CSC array indices, and the result is converted back to whatever sparse format the data was originally provided in. """ fmt = X.format if axis == 0: X = X.T # Now we're definitely rolling on the correct axis X_shear = X.tocsc(copy=True) # The idea here is to repeat the shear amount (factor * range) # by the number of non-zeros for each column. # The number of non-zeros is computed by diffing the index pointer array roll = np.repeat(factor * np.arange(X_shear.shape[1]), np.diff(X_shear.indptr)) # In-place roll np.mod(X_shear.indices + roll, X_shear.shape[0], out=X_shear.indices) if axis == 0: X_shear = X_shear.T # And convert back to the input format return X_shear.asformat(fmt)
[docs]def shear(X, factor=1, axis=-1): """Shear a matrix by a given factor. The column ``X[:, n]`` will be displaced (rolled) by ``factor * n`` This is primarily useful for converting between lag and recurrence representations: shearing with ``factor=-1`` converts the main diagonal to a horizontal. Shearing with ``factor=1`` converts a horizontal to a diagonal. Parameters ---------- X : np.ndarray [ndim=2] or scipy.sparse matrix The array to be sheared factor : integer The shear factor: ``X[:, n] -> np.roll(X[:, n], factor * n)`` axis : integer The axis along which to shear Returns ------- X_shear : same type as ``X`` The sheared matrix Examples -------- >>> E = np.eye(3) >>> librosa.util.shear(E, factor=-1, axis=-1) array([[1., 1., 1.], [0., 0., 0.], [0., 0., 0.]]) >>> librosa.util.shear(E, factor=-1, axis=0) array([[1., 0., 0.], [1., 0., 0.], [1., 0., 0.]]) >>> librosa.util.shear(E, factor=1, axis=-1) array([[1., 0., 0.], [0., 0., 1.], [0., 1., 0.]]) """ if not np.issubdtype(type(factor), np.integer): raise ParameterError("factor={} must be integer-valued".format(factor)) if scipy.sparse.isspmatrix(X): return __shear_sparse(X, factor=factor, axis=axis) else: return __shear_dense(X, factor=factor, axis=axis)
[docs]def stack(arrays, axis=0): """Stack one or more arrays along a target axis. This function is similar to `np.stack`, except that memory contiguity is retained when stacking along the first dimension. This is useful when combining multiple monophonic audio signals into a multi-channel signal, or when stacking multiple feature representations to form a multi-dimensional array. Parameters ---------- arrays : list one or more `np.ndarray` axis : integer The target axis along which to stack. ``axis=0`` creates a new first axis, and ``axis=-1`` creates a new last axis. Returns ------- arr_stack : np.ndarray [shape=(len(arrays), array_shape) or shape=(array_shape, len(arrays))] The input arrays, stacked along the target dimension. If ``axis=0``, then ``arr_stack`` will be F-contiguous. Otherwise, ``arr_stack`` will be C-contiguous by default, as computed by `np.stack`. Raises ------ ParameterError - If ``arrays`` do not all have the same shape - If no ``arrays`` are given See Also -------- numpy.stack numpy.ndarray.flags frame Examples -------- Combine two buffers into a contiguous arrays >>> y_left = np.ones(5) >>> y_right = -np.ones(5) >>> y_stereo = librosa.util.stack([y_left, y_right], axis=0) >>> y_stereo array([[ 1., 1., 1., 1., 1.], [-1., -1., -1., -1., -1.]]) >>> y_stereo.flags C_CONTIGUOUS : False F_CONTIGUOUS : True OWNDATA : True WRITEABLE : True ALIGNED : True WRITEBACKIFCOPY : False UPDATEIFCOPY : False Or along the trailing axis >>> y_stereo = librosa.util.stack([y_left, y_right], axis=-1) >>> y_stereo array([[ 1., -1.], [ 1., -1.], [ 1., -1.], [ 1., -1.], [ 1., -1.]]) >>> y_stereo.flags C_CONTIGUOUS : True F_CONTIGUOUS : False OWNDATA : True WRITEABLE : True ALIGNED : True WRITEBACKIFCOPY : False UPDATEIFCOPY : False """ shapes = {arr.shape for arr in arrays} if len(shapes) > 1: raise ParameterError("all input arrays must have the same shape") elif len(shapes) < 1: raise ParameterError("at least one input array must be provided for stack") shape_in = shapes.pop() if axis != 0: return np.stack(arrays, axis=axis) else: # If axis is 0, enforce F-ordering shape = tuple([len(arrays)] + list(shape_in)) # Find the common dtype for all inputs dtype = np.find_common_type([arr.dtype for arr in arrays], []) # Allocate an empty array of the right shape and type result = np.empty(shape, dtype=dtype, order="F") # Stack into the preallocated buffer np.stack(arrays, axis=axis, out=result) return result
[docs]def dtype_r2c(d, default=np.complex64): """Find the complex numpy dtype corresponding to a real dtype. This is used to maintain numerical precision and memory footprint when constructing complex arrays from real-valued data (e.g. in a Fourier transform). A `float32` (single-precision) type maps to `complex64`, while a `float64` (double-precision) maps to `complex128`. Parameters ---------- d : np.dtype The real-valued dtype to convert to complex. If ``d`` is a complex type already, it will be returned. default : np.dtype, optional The default complex target type, if ``d`` does not match a known dtype Returns ------- d_c : np.dtype The complex dtype See Also -------- dtype_c2r numpy.dtype Examples -------- >>> librosa.util.dtype_r2c(np.float32) dtype('complex64') >>> librosa.util.dtype_r2c(np.int16) dtype('complex64') >>> librosa.util.dtype_r2c(np.complex128) dtype('complex128') """ mapping = { np.dtype(np.float32): np.complex64, np.dtype(np.float64): np.complex128, np.dtype(np.float): np.complex, } # If we're given a complex type already, return it dt = np.dtype(d) if dt.kind == "c": return dt # Otherwise, try to map the dtype. # If no match is found, return the default. return np.dtype(mapping.get(dt, default))
[docs]def dtype_c2r(d, default=np.float32): """Find the real numpy dtype corresponding to a complex dtype. This is used to maintain numerical precision and memory footprint when constructing real arrays from complex-valued data (e.g. in an inverse Fourier transform). A `complex64` (single-precision) type maps to `float32`, while a `complex128` (double-precision) maps to `float64`. Parameters ---------- d : np.dtype The complex-valued dtype to convert to real. If ``d`` is a real (float) type already, it will be returned. default : np.dtype, optional The default real target type, if ``d`` does not match a known dtype Returns ------- d_r : np.dtype The real dtype See Also -------- dtype_r2c numpy.dtype Examples -------- >>> librosa.util.dtype_r2c(np.complex64) dtype('float32') >>> librosa.util.dtype_r2c(np.float32) dtype('float32') >>> librosa.util.dtype_r2c(np.int16) dtype('float32') >>> librosa.util.dtype_r2c(np.complex128) dtype('float64') """ mapping = { np.dtype(np.complex64): np.float32, np.dtype(np.complex128): np.float64, np.dtype(np.complex): np.float, } # If we're given a real type already, return it dt = np.dtype(d) if dt.kind == "f": return dt # Otherwise, try to map the dtype. # If no match is found, return the default. return np.dtype(mapping.get(np.dtype(d), default))