73 lines
2.4 KiB
Python
73 lines
2.4 KiB
Python
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"""
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The arraycrop module contains functions to crop values from the edges of an
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n-dimensional array.
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"""
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import numpy as np
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__all__ = ['crop']
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def crop(ar, crop_width, copy=False, order='K'):
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"""Crop array `ar` by `crop_width` along each dimension.
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Parameters
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----------
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ar : array-like of rank N
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Input array.
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crop_width : {sequence, int}
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Number of values to remove from the edges of each axis.
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``((before_1, after_1),`` ... ``(before_N, after_N))`` specifies
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unique crop widths at the start and end of each axis.
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``((before, after),) or (before, after)`` specifies
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a fixed start and end crop for every axis.
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``(n,)`` or ``n`` for integer ``n`` is a shortcut for
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before = after = ``n`` for all axes.
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copy : bool, optional
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If `True`, ensure the returned array is a contiguous copy. Normally,
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a crop operation will return a discontiguous view of the underlying
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input array.
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order : {'C', 'F', 'A', 'K'}, optional
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If ``copy==True``, control the memory layout of the copy. See
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``np.copy``.
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Returns
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-------
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cropped : array
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The cropped array. If ``copy=False`` (default), this is a sliced
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view of the input array.
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"""
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ar = np.array(ar, copy=False)
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if isinstance(crop_width, int):
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crops = [[crop_width, crop_width]] * ar.ndim
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elif isinstance(crop_width[0], int):
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if len(crop_width) == 1:
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crops = [[crop_width[0], crop_width[0]]] * ar.ndim
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elif len(crop_width) == 2:
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crops = [crop_width] * ar.ndim
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else:
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raise ValueError(
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f"crop_width has an invalid length: {len(crop_width)}\n"
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"crop_width should be a sequence of N pairs, "
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"a single pair, or a single integer"
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)
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elif len(crop_width) == 1:
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crops = [crop_width[0]] * ar.ndim
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elif len(crop_width) == ar.ndim:
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crops = crop_width
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else:
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raise ValueError(
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f"crop_width has an invalid length: {len(crop_width)}\n"
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"crop_width should be a sequence of N pairs, "
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"a single pair, or a single integer"
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)
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slices = tuple(slice(a, ar.shape[i] - b)
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for i, (a, b) in enumerate(crops))
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if copy:
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cropped = np.array(ar[slices], order=order, copy=True)
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else:
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cropped = ar[slices]
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return cropped
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