Slightly clarify the implementation of safe_masked_invalid.

Author: anntzer

lib/matplotlib/cbook/__init__.py

@@ -746,12 +746,9 @@ def safezip(*args):
 def safe_masked_invalid(x, copy=False):
     x = np.array(x, subok=True, copy=copy)
     if not x.dtype.isnative:
-        # Note that the argument to `byteswap` is 'inplace',
-        # thus if we have already made a copy, do the byteswap in
-        # place, else make a copy with the byte order swapped.
-        # Be explicit that we are swapping the byte order of the dtype
-        x = x.byteswap(copy).newbyteorder('S')
-
+        # If we have already made a copy, do the byteswap in place, else make a
+        # copy with the byte order swapped.
+        x = x.byteswap(inplace=copy).newbyteorder('N')  # Swap to native order.
     try:
         xm = np.ma.masked_invalid(x, copy=False)
         xm.shrink_mask()