fixed sub2ind and ind2sub (thin wrappers on numpy) as per Issue #58

SimPEG/Tests/test_utils.py

@@ -1,6 +1,6 @@
 import numpy as np
 import unittest
-from SimPEG.Utils import mkvc, ndgrid, indexCube, sdiag, inv3X3BlockDiagonal, inv2X2BlockDiagonal
+from SimPEG.Utils import mkvc, ndgrid, indexCube, sdiag, inv3X3BlockDiagonal, inv2X2BlockDiagonal,sub2ind,ind2sub
 from SimPEG.Tests import checkDerivative
 
 
@@ -64,6 +64,19 @@ class TestSequenceFunctions(unittest.TestCase):
         self.assertTrue(np.all(XYZ[:, 1] == X2_test))
         self.assertTrue(np.all(XYZ[:, 2] == X3_test))
 
+    def test_sub2ind(self):
+        x = np.ones((5,2))
+        self.assertTrue(np.all(sub2ind(x.shape, [0,0]) == [0]))
+        self.assertTrue(np.all(sub2ind(x.shape, [4,0]) == [4]))
+        self.assertTrue(np.all(sub2ind(x.shape, [0,1]) == [5]))
+        self.assertTrue(np.all(sub2ind(x.shape, [4,1]) == [9]))
+        self.assertTrue(np.all(sub2ind(x.shape, [[0,0],[4,0],[0,1],[4,1]]) == [0,4,5,9]))
+
+    def test_ind2sub(self):
+        x = np.ones((5,2))
+        self.assertTrue(np.all(ind2sub(x.shape, [0,4,5,9])[0] == [0,4,0,4]))
+        self.assertTrue(np.all(ind2sub(x.shape, [0,4,5,9])[1] == [0,0,1,1]))
+
     def test_indexCube_2D(self):
         nN = np.array([3, 3])
         self.assertTrue(np.all(indexCube('A', nN) == np.array([0, 1, 3, 4])))

SimPEG/Utils/matutils.py

@@ -97,35 +97,22 @@ def ndgrid(*args, **kwargs):
         else:
             return XYZ[2], XYZ[1], XYZ[0]
 
-
-def ind2sub(shape, ind):
-    """From the given shape, returns the subscrips of the given index"""
-    revshp = []
-    revshp.extend(shape)
-    mult = [1]
-    for i in range(0, len(revshp)-1):
-        mult.extend([mult[i]*revshp[i]])
-    mult = np.array(mult).reshape(len(mult))
-
-    sub = []
-
-    for i in range(0, len(shape)):
-        sub.extend([np.math.floor(ind / mult[i])])
-        ind = ind - (np.math.floor(ind/mult[i]) * mult[i])
-    return sub
-
+def ind2sub(shape, inds):
+    """From the given shape, returns the subscripts of the given index"""
+    if type(inds) is not np.ndarray:
+        inds = np.array(inds)
+    assert len(inds.shape) == 1, 'Indexing must be done as a 1D row vector, e.g. [3,6,6,...]'
+    return np.unravel_index(inds, shape, order='F')
 
 def sub2ind(shape, subs):
     """From the given shape, returns the index of the given subscript"""
-    revshp = list(shape)
-    mult = [1]
-    for i in range(0, len(revshp)-1):
-        mult.extend([mult[i]*revshp[i]])
-    mult = np.array(mult).reshape(len(mult), 1)
-
-    idx = np.dot((subs), (mult))
-    return idx
-
+    if type(subs) is not np.ndarray:
+        subs = np.array(subs)
+    if subs.size == len(shape):
+        subs = subs[np.newaxis,:]
+    assert subs.shape[1] == len(shape), 'Indexing must be done as a column vectors. e.g. [[3,6],[6,2],...]'
+    inds = np.ravel_multi_index(subs.T, shape, order='F')
+    return mkvc(inds)
 
 def getSubArray(A, ind):
     """subArray"""