From aa0532f362dc2fd398a78a838f0cd2c95cad19d8 Mon Sep 17 00:00:00 2001
From: Jaime Fernandez <jaime.frio@gmail.com>
Date: Sat, 16 May 2015 22:34:39 -0700
Subject: MANT: handling of axis in np.ma.compress_nd

Modified the handling that np.ma.compress_nd does of its 'axis'
argument, to more closely follow that of ufunc methods, including
error messages for wrong values.
---
 numpy/ma/extras.py | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

(limited to 'numpy/ma/extras.py')

diff --git a/numpy/ma/extras.py b/numpy/ma/extras.py
index 64a9844cf..3c10af24c 100644
--- a/numpy/ma/extras.py
+++ b/numpy/ma/extras.py
@@ -718,7 +718,7 @@ def median(a, axis=None, out=None, overwrite_input=False):
 #..............................................................................
 def compress_nd(x, axis=None):
     """Supress slices from multiple dimensions which contain masked values.
-    
+
     Parameters
     ----------
     x : array_like, MaskedArray
@@ -731,29 +731,27 @@ def compress_nd(x, axis=None):
         - If axis is a tuple of ints, those are the axes to supress slices from.
         - If axis is an int, then that is the only axis to supress slices from.
         - If axis is None, all axis are selected.
-    
+
     Returns
     -------
     compress_array : ndarray
-        The compressed array.        
-    """    
+        The compressed array.
+    """
     x = asarray(x)
     m = getmask(x)
     # Set axis to tuple of ints
-    if isinstance(axis, tuple):
-        axis = tuple(ax % x.ndim for ax in axis)
-    elif isinstance(axis, int):
-        axis = (axis % x.ndim,)
+    if isinstance(axis, int):
+        axis = (axis,)
     elif axis is None:
         axis = tuple(range(x.ndim))
-    else:
-        raise ValueError('Invalid type for axis argument')        
+    elif not isinstance(axis, tuple):
+        raise ValueError('Invalid type for axis argument')
     # Check axis input
-    for ax in axis:
-        if not (0 <= ax < x.ndim):
-            raise ValueError('axis %d is out of range' % ax)
-    if not len(axis) == len(set(axis)):
-        raise ValueError('axis cannot have dupliate entries')
+    axis = [ax + x.ndim if ax < 0 else ax for ax in axis]
+    if not all(0 <= ax < x.ndim for ax in axis):
+        raise ValueError("'axis' entry is out of bounds")
+    if len(axis) != len(set(axis)):
+        raise ValueError("duplicate value in 'axis'")
     # Nothing is masked: return x
     if m is nomask or not m.any():
         return x._data
@@ -766,7 +764,7 @@ def compress_nd(x, axis=None):
         axes = tuple(list(range(ax)) + list(range(ax + 1, x.ndim)))
         data = data[(slice(None),)*ax + (~m.any(axis=axes),)]
     return data
-    
+
 def compress_rowcols(x, axis=None):
     """
     Suppress the rows and/or columns of a 2-D array that contain
-- 
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