PERF: use new to_records() argument in to_stata()

Author: qwhelan

pandas/io/stata.py

@@ -2385,8 +2385,7 @@ def _prepare_data(self):
  data = self._convert_strls(data)
 
  # 3. Convert bad string data to '' and pad to correct length
- dtypes = []
- data_cols = []
+ dtypes = {}
  has_strings = False
  native_byteorder = self._byteorder == _set_endianness(sys.byteorder)
  for i, col in enumerate(data):
@@ -2395,22 +2394,16 @@ def _prepare_data(self):
  has_strings = True
  data[col] = data[col].fillna('').apply(_pad_bytes, args=(typ,))
  stype = 'S{type}'.format(type=typ)
- dtypes.append(('c' + str(i), stype))
- string = data[col].str.encode(self._encoding)
- data_cols.append(string.values.astype(stype))
+ dtypes[col] = stype
+ data[col] = data[col].str.encode(self._encoding).astype(stype)
  else:
  values = data[col].values
  dtype = data[col].dtype
  if not native_byteorder:
  dtype = dtype.newbyteorder(self._byteorder)
- dtypes.append(('c' + str(i), dtype))
- data_cols.append(values)
- dtypes = np.dtype(dtypes)
+ dtypes[col] = dtype
 
- if has_strings or not native_byteorder:
- self.data = np.fromiter(zip(*data_cols), dtype=dtypes)
- else:
- self.data = data.to_records(index=False)
+ self.data = data.to_records(index=False, column_dtypes=dtypes)
 
  def _write_data(self):
  data = self.data