numpy
diff --git a/‎doc/release/1.12.0-notes.rst‎
Lines changed: 5 additions & 0 deletions b/‎doc/release/1.12.0-notes.rst‎
Lines changed: 5 additions & 0 deletions
diff --git a/‎numpy/lib/npyio.py‎
Lines changed: 30 additions & 5 deletions b/‎numpy/lib/npyio.py‎
Lines changed: 30 additions & 5 deletions
diff --git a/‎numpy/lib/tests/test_io.py‎
Lines changed: 38 additions & 0 deletions b/‎numpy/lib/tests/test_io.py‎
Lines changed: 38 additions & 0 deletions
@@ -61,6 +61,11 @@ New Features
 Improvements
 ============
 
+*np.loadtxt* now supports a single integer as ``usecol`` argument
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+Instead of using ``usecol=(n,)`` to read the nth column of a file
+it is now allowed to use ``usecol=n``. Also the error message is
+more user friendly when a non-integer is passed as a column index.
 
 
 Changes
 
@@ -6,7 +6,7 @@
 import itertools
 import warnings
 import weakref
-from operator import itemgetter
+from operator import itemgetter, index as opindex
 
 import numpy as np
 from . import format
@@ -714,10 +714,18 @@ def loadtxt(fname, dtype=float, comments='#', delimiter=None,
         ``converters = {3: lambda s: float(s.strip() or 0)}``.  Default: None.
     skiprows : int, optional
         Skip the first `skiprows` lines; default: 0.
-    usecols : sequence, optional
-        Which columns to read, with 0 being the first.  For example,
-        ``usecols = (1,4,5)`` will extract the 2nd, 5th and 6th columns.
+
+    usecols : int or sequence, optional
+        Which columns to read, with 0 being the first. For example, 
+        usecols = (1,4,5) will extract the 2nd, 5th and 6th columns.
         The default, None, results in all columns being read.
+        
+        .. versionadded:: 1.11.0
+        
+        Also when a single column has to be read it is possible to use
+        an integer instead of a tuple. E.g ``usecols = 3`` reads the
+        third column the same way as `usecols = (3,)`` would.
+
     unpack : bool, optional
         If True, the returned array is transposed, so that arguments may be
         unpacked using ``x, y, z = loadtxt(...)``.  When used with a structured
@@ -786,8 +794,25 @@ def loadtxt(fname, dtype=float, comments='#', delimiter=None,
     user_converters = converters
     if delimiter is not None:
         delimiter = asbytes(delimiter)
+
     if usecols is not None:
-        usecols = list(usecols)
+        # Allow usecols to be a single int or a sequence of ints
+        try:
+
8000
            usecols_as_list = list(usecols)
+        except TypeError:
+            usecols_as_list = [usecols]
+        for col_idx in usecols_as_list:
+            try:
+                opindex(col_idx)
+            except TypeError as e:
+                e.args = (
+                    "usecols must be an int or a sequence of ints but "
+                    "it contains at least one element of type %s" %
+                    type(col_idx),
+                    )
+                raise
+        # Fall back to existing code
+        usecols = usecols_as_list
 
     fown = False
     try:
 
@@ -608,6 +608,29 @@ def test_usecols(self):
         x = np.loadtxt(c, dtype=float, usecols=np.array([1, 2]))
         assert_array_equal(x, a[:, 1:])
 
+        # Testing with an integer instead of a sequence
+        for int_type in [int, np.int8, np.int16,
+                         np.int32, np.int64, np.uint8, np.uint16,
+                         np.uint32, np.uint64]:
+            to_read = int_type(1)
+            c.seek(0)
+            x = np.loadtxt(c, dtype=float, usecols=to_read)
+            assert_array_equal(x, a[:, 1])
+
+        # Testing with some crazy custom integer type
+        class CrazyInt(object):
+            def __index__(self):
+                return 1
+
+        crazy_int = CrazyInt()
+        c.seek(0)
+        x = np.loadtxt(c, dtype=float, usecols=crazy_int)
+        assert_array_equal(x, a[:, 1])
+
+        c.seek(0)
+        x = np.loadtxt(c, dtype=float, usecols=(crazy_int,))
+        assert_array_equal(x, a[:, 1])
+
         # Checking with dtypes defined converters.
         data = '''JOE 70.1 25.3
                 BOB 60.5 27.9
@@ -619,6 +642,21 @@ def test_usecols(self):
         assert_equal(arr['stid'], [b"JOE", b"BOB"])
         assert_equal(arr['temp'], [25.3, 27.9])
 
+        # Testing non-ints in usecols
+        c.seek(0)
+        bogus_idx = 1.5
+        assert_raises_regex(
+            TypeError,
+            '^usecols must be.*%s' % type(bogus_idx),
+         
1E71
   np.loadtxt, c, usecols=bogus_idx
+            )
+
+        assert_raises_regex(
+            TypeError,
+            '^usecols must be.*%s' % type(bogus_idx),
+            np.loadtxt, c, usecols=[0, bogus_idx, 0]
+            )
+
     def test_fancy_dtype(self):
         c = TextIO()
         c.write('1,2,3.0\n4,5,6.0\n')