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import numpy as np |
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from sklearn.utils._array_api import get_namespace |
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def _attach_unique(y): |
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"""Attach unique values of y to y and return the result. |
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The result is a view of y, and the metadata (unique) is not attached to y. |
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""" |
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if not isinstance(y, np.ndarray): |
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return y |
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try: |
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if "unique" in y.dtype.metadata: |
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return y |
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except (AttributeError, TypeError): |
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pass |
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unique = np.unique(y) |
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unique_dtype = np.dtype(y.dtype, metadata={"unique": unique}) |
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return y.view(dtype=unique_dtype) |
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def attach_unique(*ys, return_tuple=False): |
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"""Attach unique values of ys to ys and return the results. |
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The result is a view of y, and the metadata (unique) is not attached to y. |
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IMPORTANT: The output of this function should NEVER be returned in functions. |
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This is to avoid this pattern: |
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.. code:: python |
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y = np.array([1, 2, 3]) |
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y = attach_unique(y) |
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y[1] = -1 |
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# now np.unique(y) will be different from cached_unique(y) |
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Parameters |
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---------- |
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*ys : sequence of array-like |
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Input data arrays. |
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return_tuple : bool, default=False |
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If True, always return a tuple even if there is only one array. |
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Returns |
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------- |
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ys : tuple of array-like or array-like |
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Input data with unique values attached. |
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""" |
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res = tuple(_attach_unique(y) for y in ys) |
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if len(res) == 1 and not return_tuple: |
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return res[0] |
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return res |
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def _cached_unique(y, xp=None): |
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"""Return the unique values of y. |
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Use the cached values from dtype.metadata if present. |
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This function does NOT cache the values in y, i.e. it doesn't change y. |
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Call `attach_unique` to attach the unique values to y. |
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""" |
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try: |
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if y.dtype.metadata is not None and "unique" in y.dtype.metadata: |
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return y.dtype.metadata["unique"] |
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except AttributeError: |
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pass |
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xp, _ = get_namespace(y, xp=xp) |
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return xp.unique_values(y) |
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def cached_unique(*ys, xp=None): |
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"""Return the unique values of ys. |
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Use the cached values from dtype.metadata if present. |
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This function does NOT cache the values in y, i.e. it doesn't change y. |
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Call `attach_unique` to attach the unique values to y. |
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Parameters |
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---------- |
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*ys : sequence of array-like |
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Input data arrays. |
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xp : module, default=None |
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Precomputed array namespace module. When passed, typically from a caller |
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that has already performed inspection of its own inputs, skips array |
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namespace inspection. |
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Returns |
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------- |
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res : tuple of array-like or array-like |
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Unique values of ys. |
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""" |
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res = tuple(_cached_unique(y, xp=xp) for y in ys) |
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if len(res) == 1: |
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return res[0] |
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return res |
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