2to3: Apply `map` fixer.

In Python 3 `map` is an iterator while in Python 2 it returns a list.
The simple fix applied by the fixer is to inclose all instances of map
with `list(...)`. This is not needed in all cases, and even where
appropriate list comprehensions may be preferred for their clarity.
Consequently, this patch attempts to use list comprehensions where it
makes sense.

When the mapped function has two arguments there is another problem that
can arise. In Python 3 map stops execution when the shortest argument
list is exhausted, while in Python 2 it stops when the longest argument
list is exhausted. Consequently the two argument case might need special
care. However, we have been running Python3 converted versions of numpy
since 1.5 without problems, so it is probably not something that affects
us.

Closes #3068

1 files changed, 11 insertions, 10 deletions

diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py
index 7f66fb141..600ab4a36 100644
--- a/numpy/lib/npyio.py
+++ b/numpy/lib/npyio.py
@@ -1602,7 +1602,7 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
     # Upgrade the converters (if needed)
     if dtype is None:
         for (i, converter) in enumerate(converters):
-            current_column = map(itemgetter(i), rows)
+            current_column = [itemgetter(i)(_m) for _m in rows]
             try:
                 converter.iterupgrade(current_column)
             except ConverterLockError:
@@ -1653,18 +1653,19 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
 
     # Convert each value according to the converter:
     # We want to modify the list in place to avoid creating a new one...
-#    if loose:
-#        conversionfuncs = [conv._loose_call for conv in converters]
-#    else:
-#        conversionfuncs = [conv._strict_call for conv in converters]
-#    for (i, vals) in enumerate(rows):
-#        rows[i] = tuple([convert(val)
-#                         for (convert, val) in zip(conversionfuncs, vals)])
+    #
+    #    if loose:
+    #        conversionfuncs = [conv._loose_call for conv in converters]
+    #    else:
+    #        conversionfuncs = [conv._strict_call for conv in converters]
+    #    for (i, vals) in enumerate(rows):
+    #        rows[i] = tuple([convert(val)
+    #                         for (convert, val) in zip(conversionfuncs, vals)])
     if loose:
-        rows = zip(*[map(converter._loose_call, map(itemgetter(i), rows))
+        rows = zip(*[[converter._loose_call(_r) for _r in map(itemgetter(i), rows)]
                      for (i, converter) in enumerate(converters)])
     else:
-        rows = zip(*[map(converter._strict_call, map(itemgetter(i), rows))
+        rows = zip(*[[converter._strict_call(_r) for _r in map(itemgetter(i), rows)]
                      for (i, converter) in enumerate(converters)])
     # Reset the dtype
     data = rows