ENH: Add Stata 119 writer

doc/source/whatsnew/v1.0.0.rst

@@ -223,7 +223,7 @@ Other enhancements
 - :meth:`DataFrame.sort_values` and :meth:`Series.sort_values` have gained ``ignore_index`` keyword to be able to reset index after sorting (:issue:`30114`)
 - :meth:`DataFrame.sort_index` and :meth:`Series.sort_index` have gained ``ignore_index`` keyword to reset index (:issue:`30114`)
 - :meth:`DataFrame.drop_duplicates` has gained ``ignore_index`` keyword to reset index (:issue:`30114`)
-- Added new writer for exporting Stata dta files in version 118, ``StataWriter118``.  This format supports exporting strings containing Unicode characters (:issue:`23573`)
+- Added new writer for exporting Stata dta files in versions 118 and 119, ``StataWriterUTF8``.  These files formats support exporting strings containing Unicode characters. Format 119 supports data sets with more than 32,767 variables (:issue:`23573`, :issue:`30959`)
 - :meth:`Series.map` now accepts ``collections.abc.Mapping`` subclasses as a mapper (:issue:`29733`)
 - Added an experimental :attr:`~DataFrame.attrs` for storing global metadata about a dataset (:issue:`29062`)
 - :meth:`Timestamp.fromisocalendar` is now compatible with python 3.8 and above (:issue:`28115`)

pandas/core/frame.py

@@ -1898,14 +1898,22 @@ def to_stata(
         variable_labels : dict
             Dictionary containing columns as keys and variable labels as
             values. Each label must be 80 characters or smaller.
-        version : {114, 117}, default 114
-            Version to use in the output dta file.  Version 114 can be used
-            read by Stata 10 and later.  Version 117 can be read by Stata 13
-            or later. Version 114 limits string variables to 244 characters or
-            fewer while 117 allows strings with lengths up to 2,000,000
-            characters.
+        version : {114, 117, 118, 119, None}, default 114
+            Version to use in the output dta file. Set to None to let pandas
+            decide between 118 or 119 formats depending on the number of
+            columns in the frame. Version 114 can be read by Stata 10 and
+            later. Version 117 can be read by Stata 13 or later. Version 118
+            is supported in Stata 14 and later. Version 119 is supported in
+            Stata 15 and later. Version 114 limits string variables to 244
+            characters or fewer while versions 117 and later allow strings
+            with lengths up to 2,000,000 characters. Versions 118 and 119
+            support Unicode characters, and version 119 supports more than
+            32,767 variables.
 
             .. versionadded:: 0.23.0
+            .. versionchanged:: 1.0.0
+
+                Added support for formats 118 and 119.
 
         convert_strl : list, optional
             List of column names to convert to string columns to Stata StrL
@@ -1939,20 +1947,24 @@ def to_stata(
         ...                    'speed': [350, 18, 361, 15]})
         >>> df.to_stata('animals.dta')  # doctest: +SKIP
         """
-        kwargs = {}
-        if version not in (114, 117, 118):
-            raise ValueError("Only formats 114, 117 and 118 are supported.")
+        if version not in (114, 117, 118, 119, None):
+            raise ValueError("Only formats 114, 117, 118 and 119 are supported.")
         if version == 114:
             if convert_strl is not None:
                 raise ValueError("strl is not supported in format 114")
             from pandas.io.stata import StataWriter as statawriter
-        else:
-            if version == 117:
-                from pandas.io.stata import StataWriter117 as statawriter
-            else:
-                from pandas.io.stata import StataWriter118 as statawriter
+        elif version == 117:
+            from pandas.io.stata import StataWriter117 as statawriter
+        else:  # versions 118 and 119
+            from pandas.io.stata import StataWriterUTF8 as statawriter
 
+        kwargs = {}
+        if version is None or version >= 117:
+            # strl conversion is only supported >= 117
             kwargs["convert_strl"] = convert_strl
+        if version is None or version >= 118:
+            # Specifying the version is only supported for UTF8 (118 or 119)
+            kwargs["version"] = version
 
         writer = statawriter(
             path,

pandas/io/stata.py

@@ -15,14 +15,15 @@
 import os
 import struct
 import sys
-from typing import Any
+from typing import Any, Dict, Hashable, Optional, Sequence
 import warnings
 
 from dateutil.relativedelta import relativedelta
 import numpy as np
 
 from pandas._libs.lib import infer_dtype
 from pandas._libs.writers import max_len_string_array
+from pandas._typing import FilePathOrBuffer
 from pandas.util._decorators import Appender
 
 from pandas.core.dtypes.common import (
@@ -47,9 +48,10 @@
 from pandas.io.common import get_filepath_or_buffer, stringify_path
 
 _version_error = (
-    "Version of given Stata file is not 104, 105, 108, "
-    "111 (Stata 7SE), 113 (Stata 8/9), 114 (Stata 10/11), "
-    "115 (Stata 12), 117 (Stata 13), or 118 (Stata 14)"
+    "Version of given Stata file is {version}. pandas supports importing "
+    "versions 104, 105, 108, 111 (Stata 7SE), 113 (Stata 8/9), "
+    "114 (Stata 10/11), 115 (Stata 12), 117 (Stata 13), 118 (Stata 14/15/16),"
+    "and 119 (Stata 15/16, over 32,767 variables)."
 )
 
 _statafile_processing_params1 = """\
@@ -1090,11 +1092,11 @@ def _read_header(self):
         self.col_sizes = [self._calcsize(typ) for typ in self.typlist]
 
     def _read_new_header(self, first_char):
-        # The first part of the header is common to 117 and 118.
+        # The first part of the header is common to 117 - 119.
         self.path_or_buf.read(27)  # stata_dta><header><release>
         self.format_version = int(self.path_or_buf.read(3))
         if self.format_version not in [117, 118, 119]:
-            raise ValueError(_version_error)
+            raise ValueError(_version_error.format(version=self.format_version))
         self._set_encoding()
         self.path_or_buf.read(21)  # </release><byteorder>
         self.byteorder = self.path_or_buf.read(3) == b"MSF" and ">" or "<"
@@ -1287,7 +1289,7 @@ def _get_seek_variable_labels(self):
     def _read_old_header(self, first_char):
         self.format_version = struct.unpack("b", first_char)[0]
         if self.format_version not in [104, 105, 108, 111, 113, 114, 115]:
-            raise ValueError(_version_error)
+            raise ValueError(_version_error.format(version=self.format_version))
         self._set_encoding()
         self.byteorder = (
             struct.unpack("b", self.path_or_buf.read(1))[0] == 0x1 and ">" or "<"
@@ -2695,7 +2697,7 @@ def _convert_key(self, key):
 
     def generate_table(self):
         """
-        Generates the GSO lookup table for the DataFRame
+        Generates the GSO lookup table for the DataFrame
 
         Returns
         -------
@@ -2934,9 +2936,9 @@ def _write_header(self, data_label=None, time_stamp=None):
         bio.write(self._tag(bytes(str(self._dta_version), "utf-8"), "release"))
         # byteorder
         bio.write(self._tag(byteorder == ">" and "MSF" or "LSF", "byteorder"))
-        # number of vars, 2 bytes
-        assert self.nvar < 2 ** 16
-        bio.write(self._tag(struct.pack(byteorder + "H", self.nvar), "K"))
+        # number of vars, 2 bytes in 117 and 118, 4 byte in 119
+        nvar_type = "H" if self._dta_version <= 118 else "I"
+        bio.write(self._tag(struct.pack(byteorder + nvar_type, self.nvar), "K"))
         # 117 uses 4 bytes, 118 uses 8
         nobs_size = "I" if self._dta_version == 117 else "Q"
         bio.write(self._tag(struct.pack(byteorder + nobs_size, self.nobs), "N"))
@@ -3033,7 +3035,8 @@ def _write_varnames(self):
 
     def _write_sortlist(self):
         self._update_map("sortlist")
-        self._file.write(self._tag(b"\x00\00" * (self.nvar + 1), "sortlist"))
+        sort_size = 2 if self._dta_version < 119 else 4
+        self._file.write(self._tag(b"\x00" * sort_size * (self.nvar + 1), "sortlist"))
 
     def _write_formats(self):
         self._update_map("formats")
@@ -3173,13 +3176,14 @@ def _set_formats_and_types(self, dtypes):
             )
 
 
-class StataWriter118(StataWriter117):
+class StataWriterUTF8(StataWriter117):
     """
-    A class for writing Stata binary dta files in Stata 15 format (118)
+    Stata binary dta file writing in Stata 15 (118) and 16 (119) formats
 
-    DTA 118 format files support unicode string data (both fixed and strL)
-    format. Unicode is also supported in value labels, variable labels and
-    the dataset label.
+    DTA 118 and 119 format files support unicode string data (both fixed
+    and strL) format. Unicode is also supported in value labels, variable
+    labels and the dataset label. Format 119 is automatically used if the
+    file contains more than 32,767 variables.
 
     .. versionadded:: 1.0.0
 
@@ -3192,34 +3196,38 @@ class StataWriter118(StataWriter117):
         is written.
     data : DataFrame
         Input to save
-    convert_dates : dict
+    convert_dates : dict, default None
         Dictionary mapping columns containing datetime types to stata internal
         format to use when writing the dates. Options are 'tc', 'td', 'tm',
         'tw', 'th', 'tq', 'ty'. Column can be either an integer or a name.
         Datetime columns that do not have a conversion type specified will be
         converted to 'tc'. Raises NotImplementedError if a datetime column has
         timezone information
-    write_index : bool
+    write_index : bool, default True
         Write the index to Stata dataset.
-    byteorder : str
+    byteorder : str, default None
         Can be ">", "<", "little", or "big". default is `sys.byteorder`
-    time_stamp : datetime
+    time_stamp : datetime, default None
         A datetime to use as file creation date.  Default is the current time
-    data_label : str
+    data_label : str, default None
         A label for the data set.  Must be 80 characters or smaller.
-    variable_labels : dict
+    variable_labels : dict, default None
         Dictionary containing columns as keys and variable labels as values.
         Each label must be 80 characters or smaller.
-    convert_strl : list
+    convert_strl : list, default None
         List of columns names to convert to Stata StrL format.  Columns with
         more than 2045 characters are automatically written as StrL.
         Smaller columns can be converted by including the column name.  Using
         StrLs can reduce output file size when strings are longer than 8
         characters, and either frequently repeated or sparse.
+    version : int, default None
+        The dta version to use. By default, uses the size of data to determine
+        the version. 118 is used if data.shape[1] <= 32767, and 119 is used
+        for storing larger DataFrames.
 
     Returns
     -------
-    StataWriter118
+    StataWriterUTF8
         The instance has a write_file method, which will write the file to the
         given `fname`.
 
@@ -3238,24 +3246,60 @@ class StataWriter118(StataWriter117):
     --------
     Using Unicode data and column names
 
-    >>> from pandas.io.stata import StataWriter118
+    >>> from pandas.io.stata import StataWriterUTF8
     >>> data = pd.DataFrame([[1.0, 1, 'ᴬ']], columns=['a', 'β', 'ĉ'])
-    >>> writer = StataWriter118('./data_file.dta', data)
+    >>> writer = StataWriterUTF8('./data_file.dta', data)
     >>> writer.write_file()
 
     Or with long strings stored in strl format
 
     >>> data = pd.DataFrame([['ᴀ relatively long ŝtring'], [''], ['']],
     ...                     columns=['strls'])
-    >>> writer = StataWriter118('./data_file_with_long_strings.dta', data,
-    ...                         convert_strl=['strls'])
+    >>> writer = StataWriterUTF8('./data_file_with_long_strings.dta', data,
+    ...                          convert_strl=['strls'])
     >>> writer.write_file()
     """
 
     _encoding = "utf-8"
-    _dta_version = 118
 
-    def _validate_variable_name(self, name):
+    def __init__(
+        self,
+        fname: FilePathOrBuffer,
+        data: DataFrame,
+        convert_dates: Optional[Dict[Hashable, str]] = None,
+        write_index: bool = True,
+        byteorder: Optional[str] = None,
+        time_stamp: Optional[datetime.datetime] = None,
+        data_label: Optional[str] = None,
+        variable_labels: Optional[Dict[Hashable, str]] = None,
+        convert_strl: Optional[Sequence[Hashable]] = None,
+        version: Optional[int] = None,
+    ):
+        if version is None:
+            version = 118 if data.shape[1] <= 32767 else 119
+        elif version not in (118, 119):
+            raise ValueError("version must be either 118 or 119.")
+        elif version == 118 and data.shape[1] > 32767:
+            raise ValueError(
+                "You must use version 119 for data sets containing more than"
+                "32,767 variables"
+            )
+
+        super().__init__(
+            fname,
+            data,
+            convert_dates=convert_dates,
+            write_index=write_index,
+            byteorder=byteorder,
+            time_stamp=time_stamp,
+            data_label=data_label,
+            variable_labels=variable_labels,
+            convert_strl=convert_strl,
+        )
+        # Override version set in StataWriter117 init
+        self._dta_version = version
+
+    def _validate_variable_name(self, name: str) -> str:
         """
         Validate variable names for Stata export.
 
@@ -3272,7 +3316,7 @@ def _validate_variable_name(self, name):
 
         Notes
         -----
-        Stata 118 support most unicode characters. The only limatation is in
+        Stata 118+ support most unicode characters. The only limitation is in
         the ascii range where the characters supported are a-z, A-Z, 0-9 and _.
         """
         # High code points appear to be acceptable