[numpy] init some useful numpy functions

numpy.py

+# -*- coding: utf-8 -*-
+
+import numpy as np
+
+
+def one_hot(a):
+    o_h = np.zeros((a.size, a.max() + 1))
+    o_h[np.arange(a.size), a] = 1
+    return o_h
+
+
+def array_to_hist(values, bins):
+    hist = np.histogram2d([0.0], [0.0], bins=bins)
+    hist = list(hist)
+    hist[0] = values
+    hist = tuple(hist)
+    return hist
+
+
+def swap_rows(a, swp, roll=1, swp_to=None):
+    """Swaps rows in the last dimension of a.
+        The rows to swap are specified by the swp argument.
+        If swp_to is defined, the rows to swap the rows from swp
+        in can be directly specified, if not, the swapping is done
+        in a rolling manner.
+    Returns:
+        Array with swapped rows
+    """
+    if not (swp_to):
+        a[..., swp] = a[..., np.roll(swp, roll)]
+        return a
+    else:
+        a[..., swp] = a[..., swp_to]
+        return a
+
+
+def create_swaps(swap_length, circle, length):
+    start = -swap_length if circle else 0
+    return np.column_stack(
+        (np.arange(start, length - swap_length), np.arange(start + swap_length, length))
+    )
+
+
+def _axis_clip(ref, axis):
+    assert -ref <= axis < ref
+    axis = ref + axis if axis < 0 else axis
+    return axis, ref - axis - 1
+
+
+def xsel(source, saxis, indices, iaxis=-1):
+    return source[xsel_mask(source, saxis, indices, iaxis)]
+
+
+def xsel_mask(source, saxis, indices, iaxis=-1):
+    saxis, safter = _axis_clip(source.ndim, saxis)
+    iaxis, iafter = _axis_clip(indices.ndim, iaxis)
+    assert iaxis <= saxis
+    assert iafter <= safter
+    indices = indices[((None,) * (saxis - iaxis)) + (Ellipsis,) + ((None,) * (safter - iafter))]
+    grid = np.ogrid[tuple(map(slice, source.shape))]
+    grid[saxis] = indices
+    return tuple(grid)
+
+
+def template_to(inp, template):
+    return np.argsort(
+        xsel(np.argsort(inp, axis=-1), 1, np.argsort(np.argsort(template, axis=-1), axis=-1), 1),
+        axis=-1,
+    )