BUG: closes #705, csv is encoded utf-8 and then decoded on the read side

pandas/core/common.py

@@ -21,6 +21,8 @@
 
 import pandas._tseries as lib
 from pandas.util import py3compat
+import codecs
+import csv
 
 # XXX: HACK for NumPy 1.5.1 to suppress warnings
 try:
@@ -828,3 +830,40 @@ def console_encode(value):
         return value.encode(sys.stdin.encoding, 'replace')
     except (AttributeError, TypeError):
         return value.encode('ascii', 'replace')
+
+def csv_encode(value):
+    if py3compat.PY3 or not isinstance(value, unicode):
+        return value
+
+    return value.encode('UTF-8', 'replace')
+
+class UTF8Recoder:
+    """
+    Iterator that reads an encoded stream and reencodes the input to UTF-8
+    """
+    def __init__(self, f, encoding):
+        self.reader = codecs.getreader(encoding)(f)
+
+    def __iter__(self):
+        return self
+
+    def next(self):
+        return self.reader.next().encode("utf-8")
+
+class UnicodeReader:
+    """
+    A CSV reader which will iterate over lines in the CSV file "f",
+    which is encoded in the given encoding.
+    """
+
+    def __init__(self, f, dialect=csv.excel, encoding="utf-8", **kwds):
+        f = UTF8Recoder(f, encoding)
+        self.reader = csv.reader(f, dialect=dialect, **kwds)
+
+    def next(self):
+        row = self.reader.next()
+        return [unicode(s, "utf-8") for s in row]
+
+    def __iter__(self):
+        return self
+

pandas/core/frame.py

@@ -23,7 +23,7 @@
 import numpy.ma as ma
 
 from pandas.core.common import (isnull, notnull, PandasError, _try_sort,
-                                _default_index, _stringify)
+                                _default_index, _stringify, csv_encode)
 from pandas.core.daterange import DateRange
 from pandas.core.generic import NDFrame
 from pandas.core.index import Index, MultiIndex, NULL_INDEX, _ensure_index
@@ -890,9 +890,13 @@ def to_csv(self, path, sep=",", na_rep='', cols=None, header=True,
                 elif not isinstance(index_label, (list, tuple, np.ndarray)):
                     # given a string for a DF with Index
                     index_label = [index_label]
-                csvout.writerow(list(index_label) + list(cols))
+
+                encoded_labels = [csv_encode(val) for val in index_label]
+                encoded_cols = [csv_encode(val) for val in cols]
+                csvout.writerow(encoded_labels + encoded_cols)
             else:
-                csvout.writerow(cols)
+                encoded_cols = [csv_encode(val) for val in cols]
+                csvout.writerow(encoded_cols)
 
         nlevels = getattr(self.index, 'nlevels', 1)
         for idx in self.index:
@@ -909,7 +913,8 @@ def to_csv(self, path, sep=",", na_rep='', cols=None, header=True,
 
                 row_fields.append(val)
 
-            csvout.writerow(row_fields)
+            encoded_rows = [csv_encode(val) for val in row_fields]
+            csvout.writerow(encoded_rows)
 
         f.close()
 

pandas/io/parsers.py

@@ -261,8 +261,9 @@ def _make_reader(self, f):
                 self.pos += 1
                 sniffed = csv.Sniffer().sniff(line)
                 dia.delimiter = sniffed.delimiter
-                self.buf.extend(list(csv.reader(StringIO(line), dialect=dia)))
-            reader = csv.reader(f, dialect=dia)
+                self.buf.extend(list(com.UnicodeReader(StringIO(line),
+                                dialect=dia)))
+            reader = com.UnicodeReader(f, dialect=dia)
         else:
             reader = (re.split(sep, line.strip()) for line in f)
 

pandas/tests/test_frame.py

@@ -2482,6 +2482,15 @@ def test_to_csv_bug(self):
 
         os.remove(path)
 
+    def test_to_csv_unicode(self):
+        from pandas import read_csv
+        path = '__tmp__.csv'
+        df = DataFrame({u'c/\u03c3':[1,2,3]})
+        df.to_csv(path)
+        df2 = read_csv(path, index_col=0)
+        assert_frame_equal(df, df2)
+        os.remove(path)
+
     def test_info(self):
         io = StringIO()
         self.frame.info(buf=io)