Add unique_rows function

skimage/util/unique.py

@@ -0,0 +1,36 @@
+import numpy as np
+
+
+def unique_rows(ar):
+    """Remove repeated rows from a 2D array.
+
+    Parameters
+    ----------
+    ar : 2D np.ndarray
+        The input array.
+
+    Returns
+    -------
+    ar_out : 2D np.ndarray
+        A copy of the input array with repeated rows removed.
+
+    Raises
+    ------
+    ValueError : if `ar` is not two-dimensional.
+
+    Examples
+    --------
+    >>> ar = np.array([[1, 0, 1],
+                       [0, 1, 0],
+                       [1, 0, 1]], np.uint8)
+    >>> aru = unique_rows(ar)
+    array([[0, 1, 0],
+           [1, 0, 1]], dtype=uint8)
+    """
+    if ar.ndim != 2:
+        raise ValueError("unique_rows() only makes sense for 2D arrays, "
+                         "got %dd" % ar.ndim)
+    ar_row_view = ar.view('|S%d' % (ar.itemsize * ar.shape[1]))
+    _, unique_row_indices = np.unique(ar_row_view, return_index=True)
+    ar_out = ar[unique_row_indices]
+    return ar_out