Add support of 'decimal' option to Series.to_csv and Dataframe.to_csv

pandas/core/format.py

@@ -1169,7 +1169,7 @@ def __init__(self, obj, path_or_buf=None, sep=",", na_rep='', float_format=None,
                  mode='w', nanRep=None, encoding=None, quoting=None,
                  line_terminator='\n', chunksize=None, engine=None,
                  tupleize_cols=False, quotechar='"', date_format=None,
-                 doublequote=True, escapechar=None):
+                 doublequote=True, escapechar=None, decimal='.'):
 
         self.engine = engine  # remove for 0.13
         self.obj = obj
@@ -1181,6 +1181,7 @@ def __init__(self, obj, path_or_buf=None, sep=",", na_rep='', float_format=None,
         self.sep = sep
         self.na_rep = na_rep
         self.float_format = float_format
+        self.decimal = decimal
 
         self.header = header
         self.index = index
@@ -1509,6 +1510,7 @@ def _save_chunk(self, start_i, end_i):
             b = self.blocks[i]
             d = b.to_native_types(slicer=slicer, na_rep=self.na_rep,
                                   float_format=self.float_format,
+                                  decimal=self.decimal,
                                   date_format=self.date_format)
 
             for col_loc, col in zip(b.mgr_locs, d):

pandas/core/frame.py

@@ -1073,7 +1073,7 @@ def to_csv(self, path_or_buf=None, sep=",", na_rep='', float_format=None,
                mode='w', encoding=None, quoting=None,
                quotechar='"', line_terminator='\n', chunksize=None,
                tupleize_cols=False, date_format=None, doublequote=True,
-               escapechar=None, **kwds):
+               escapechar=None, decimal='.', **kwds):
         r"""Write DataFrame to a comma-separated values (csv) file
 
         Parameters
@@ -1126,6 +1126,8 @@ def to_csv(self, path_or_buf=None, sep=",", na_rep='', float_format=None,
         date_format : string, default None
             Format string for datetime objects
         cols : kwarg only alias of columns [deprecated]
+        decimal: string, default '.'
+            Character recognized as decimal separator. E.g. use ‘,’ for European data
         """
 
         formatter = fmt.CSVFormatter(self, path_or_buf,
@@ -1140,7 +1142,8 @@ def to_csv(self, path_or_buf=None, sep=",", na_rep='', float_format=None,
                                      tupleize_cols=tupleize_cols,
                                      date_format=date_format,
                                      doublequote=doublequote,
-                                     escapechar=escapechar)
+                                     escapechar=escapechar,
+                                     decimal=decimal)
         formatter.save()
 
         if path_or_buf is None:

pandas/core/internals.py

@@ -1161,7 +1161,7 @@ def _try_cast(self, element):
         except:  # pragma: no cover
             return element
 
-    def to_native_types(self, slicer=None, na_rep='', float_format=None,
+    def to_native_types(self, slicer=None, na_rep='', float_format=None, decimal='.',
                         **kwargs):
         """ convert to our native types format, slicing if desired """
 
@@ -1171,10 +1171,17 @@ def to_native_types(self, slicer=None, na_rep='', float_format=None,
         values = np.array(values, dtype=object)
         mask = isnull(values)
         values[mask] = na_rep
+        if not float_format and decimal != '.':
+            float_format = '%f'
         if float_format:
             imask = (~mask).ravel()
             values.flat[imask] = np.array(
                 [float_format % val for val in values.ravel()[imask]])
+        if decimal != '.':
+            imask = (~mask).ravel()
+            values.flat[imask] = np.array(
+                [val.replace('.',',',1) for val in values.ravel()[imask]])
+
         return values.tolist()
 
     def should_store(self, value):

pandas/core/series.py

@@ -2239,7 +2239,7 @@ def from_csv(cls, path, sep=',', parse_dates=True, header=None,
     def to_csv(self, path, index=True, sep=",", na_rep='',
                float_format=None, header=False,
                index_label=None, mode='w', nanRep=None, encoding=None,
-               date_format=None):
+               date_format=None, decimal='.'):
         """
         Write Series to a comma-separated values (csv) file
 
@@ -2267,14 +2267,16 @@ def to_csv(self, path, index=True, sep=",", na_rep='',
             non-ascii, for python versions prior to 3
         date_format: string, default None
             Format string for datetime objects.
+        decimal: string, default '.'
+            Character recognized as decimal separator. E.g. use ‘,’ for European data
         """
         from pandas.core.frame import DataFrame
         df = DataFrame(self)
         # result is only a string if no path provided, otherwise None
         result = df.to_csv(path, index=index, sep=sep, na_rep=na_rep,
                   float_format=float_format, header=header,
                   index_label=index_label, mode=mode, nanRep=nanRep,
-                  encoding=encoding, date_format=date_format)
+                  encoding=encoding, date_format=date_format, decimal=decimal)
         if path is None:
             return result