ENH: genfromtxt: Change 'nrows' to 'max_rows'.

1 files changed, 17 insertions, 18 deletions

diff --git a/numpy/lib/npyio.py b/numpy/lib/npyio.py
index c8cebaed8..db1d87435 100644
--- a/numpy/lib/npyio.py
+++ b/numpy/lib/npyio.py
@@ -1205,7 +1205,7 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
                excludelist=None, deletechars=None, replace_space='_',
                autostrip=False, case_sensitive=True, defaultfmt="f%i",
                unpack=None, usemask=False, loose=True, invalid_raise=True,
-               nrows=None):
+               max_rows=None):
     """
     Load data from a text file, with missing values handled as specified.
 
@@ -1286,9 +1286,10 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
         If True, an exception is raised if an inconsistency is detected in the
         number of columns.
         If False, a warning is emitted and the offending lines are skipped.
-    nrows : int,  optional
-        The number of rows to read. Must not be used with skip_footer at the
-        same time.
+    max_rows : int,  optional
+        The maximum number of rows to read. Must not be used with skip_footer
+        at the same time.  If given, the value must be at least 1. Default is
+        to read the entire file.
 
         .. versionadded:: 1.10.0
 
@@ -1359,11 +1360,13 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
           dtype=[('intvar', '<i8'), ('fltvar', '<f8'), ('strvar', '|S5')])
 
     """
-    # Check keywords conflict
-    if skip_footer and (nrows is not None):
-        raise ValueError(
-                "keywords 'skip_footer' and 'nrows' can not be specified "
-                "at the same time")
+    if max_rows is not None:
+        if skip_footer:
+            raise ValueError(
+                    "The keywords 'skip_footer' and 'max_rows' can not be "
+                    "specified at the same time.")
+        if max_rows < 1:
+            raise ValueError("'max_rows' must be at least 1.")
 
     # Py3 data conversions to bytes, for convenience
     if comments is not None:
@@ -1654,15 +1657,13 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
 
     # Parse each line
     for (i, line) in enumerate(itertools.chain([first_line, ], fhd)):
-        if (nrows is not None) and (len(rows) >= nrows):
-            break
         values = split_line(line)
         nbvalues = len(values)
         # Skip an empty line
         if nbvalues == 0:
             continue
-        # Select only the columns we need
         if usecols:
+            # Select only the columns we need
             try:
                 values = [values[_] for _ in usecols]
             except IndexError:
@@ -1675,16 +1676,14 @@ def genfromtxt(fname, dtype=float, comments='#', delimiter=None,
         append_to_rows(tuple(values))
         if usemask:
             append_to_masks(tuple([v.strip() in m
-                                   for (v, m) in zip(values, missing_values)]))
+                                   for (v, m) in zip(values,
+                                                     missing_values)]))
+        if len(rows) == max_rows:
+            break
 
     if own_fhd:
         fhd.close()
 
-    if (nrows is not None) and (len(rows) != nrows):
-        raise AssertionError(
-                "%d rows required but got %d valid rows instead"
-                %(nrows,  len(rows)))
-
     # Upgrade the converters (if needed)
     if dtype is None:
         for (i, converter) in enumerate(converters):