Openpyxl engine for reading excel files

doc/source/whatsnew/v0.25.0.rst

@@ -159,6 +159,7 @@ Other enhancements
 - Added support for reading SPSS .sav files using :func:`read_spss` (:issue:`26537`)
 - Added new option ``plotting.backend`` to be able to select a plotting backend different than the existing ``matplotlib`` one. Use ``pandas.set_option('plotting.backend', '<backend-module>')`` where ``<backend-module`` is a library implementing the pandas plotting API (:issue:`14130`)
 - :class:`pandas.offsets.BusinessHour` supports multiple opening hours intervals (:issue:`15481`)
+- :func:`read_excel` can now use ``openpyxl`` to read Excel files via the ``engine='openpyxl'`` argument. This will become the default in a future release (:issue:`11499`)
 
 .. _whatsnew_0250.api_breaking:
 

pandas/_typing.py

@@ -24,3 +24,4 @@
 FilePathOrBuffer = Union[str, Path, IO[AnyStr]]
 
 FrameOrSeries = TypeVar('FrameOrSeries', ABCSeries, ABCDataFrame)
+Scalar = Union[str, int, float]

pandas/core/config_init.py

@@ -411,7 +411,43 @@ def use_inf_as_na_cb(key):
  cf.register_option('chained_assignment', 'warn', chained_assignment,
  validator=is_one_of_factory([None, 'warn', 'raise']))
 
-# Set up the io.excel specific configuration.
+
+# Set up the io.excel specific reader configuration.
+reader_engine_doc = """
+: string
+ The default Excel reader engine for '{ext}' files. Available options:
+ auto, {others}.
+"""
+
+_xls_options = ['xlrd']
+_xlsm_options = ['xlrd', 'openpyxl']
+_xlsx_options = ['xlrd', 'openpyxl']
+
+
+with cf.config_prefix("io.excel.xls"):
+ cf.register_option("reader", "auto",
+ reader_engine_doc.format(
+ ext='xls',
+ others=', '.join(_xls_options)),
+ validator=str)
+
+with cf.config_prefix("io.excel.xlsm"):
+ cf.register_option("reader", "auto",
+ reader_engine_doc.format(
+ ext='xlsm',
+ others=', '.join(_xlsm_options)),
+ validator=str)
+
+
+with cf.config_prefix("io.excel.xlsx"):
+ cf.register_option("reader", "auto",
+ reader_engine_doc.format(
+ ext='xlsx',
+ others=', '.join(_xlsx_options)),
+ validator=str)
+
+
+# Set up the io.excel specific writer configuration.
 writer_engine_doc = """
 : string
  The default Excel writer engine for '{ext}' files. Available options:

pandas/io/excel/_base.py

@@ -422,7 +422,7 @@ def parse(self,
  data = self.get_sheet_data(sheet, convert_float)
  usecols = _maybe_convert_usecols(usecols)
 
- if sheet.nrows == 0:
+ if not data:
  output[asheetname] = DataFrame()
  continue
 
@@ -769,9 +769,11 @@ class ExcelFile:
  """
 
  from pandas.io.excel._xlrd import _XlrdReader
+ from pandas.io.excel._openpyxl import _OpenpyxlReader
 
  _engines = {
  'xlrd': _XlrdReader,
+ 'openpyxl': _OpenpyxlReader,
  }
 
  def __init__(self, io, engine=None):

pandas/io/excel/_openpyxl.py

@@ -1,4 +1,12 @@
-from pandas.io.excel._base import ExcelWriter
+from typing import List
+
+import numpy as np
+
+from pandas.compat._optional import import_optional_dependency
+
+from pandas._typing import FilePathOrBuffer, Scalar
+
+from pandas.io.excel._base import ExcelWriter, _BaseExcelReader
 from pandas.io.excel._util import _validate_freeze_panes
 
 
@@ -451,3 +459,67 @@ def write_cells(self, cells, sheet_name=None, startrow=0, startcol=0,
  xcell = wks.cell(column=col, row=row)
  for k, v in style_kwargs.items():
  setattr(xcell, k, v)
+
+
+class _OpenpyxlReader(_BaseExcelReader):
+
+ def __init__(self, filepath_or_buffer: FilePathOrBuffer) -> None:
+ """Reader using openpyxl engine.
+
+ Parameters
+ ----------
+ filepath_or_buffer : string, path object or Workbook
+ Object to be parsed.
+ """
+ import_optional_dependency("openpyxl")
+ super().__init__(filepath_or_buffer)
+
+ @property
+ def _workbook_class(self):
+ from openpyxl import Workbook
+ return Workbook
+
+ def load_workbook(self, filepath_or_buffer: FilePathOrBuffer):
+ from openpyxl import load_workbook
+ return load_workbook(filepath_or_buffer,
+ read_only=True, data_only=True)
+
+ @property
+ def sheet_names(self) -> List[str]:
+ return self.book.sheetnames
+
+ def get_sheet_by_name(self, name: str):
+ return self.book[name]
+
+ def get_sheet_by_index(self, index: int):
+ return self.book.worksheets[index]
+
+ def _convert_cell(self, cell, convert_float: bool) -> Scalar:
+
+ # TODO: replace with openpyxl constants
+ if cell.is_date:
+ return cell.value
+ elif cell.data_type == 'e':
+ return np.nan
+ elif cell.data_type == 'b':
+ return bool(cell.value)
+ elif cell.value is None:
+ return '' # compat with xlrd
+ elif cell.data_type == 'n':
+ # GH5394
+ if convert_float:
+ val = int(cell.value)
+ if val == cell.value:
+ return val
+ else:
+ return float(cell.value)
+
+ return cell.value
+
+ def get_sheet_data(self, sheet, convert_float: bool) -> List[List[Scalar]]:
+ data = [] # type: List[List[Scalar]]
+ for row in sheet.rows:
+ data.append(
+ [self._convert_cell(cell, convert_float) for cell in row])
+
+ return data

pandas/tests/io/excel/test_readers.py

@@ -38,13 +38,17 @@ class TestReaders:
  # Add any engines to test here
  pytest.param('xlrd', marks=pytest.mark.skipif(
  not td.safe_import("xlrd"), reason="no xlrd")),
+ pytest.param('openpyxl', marks=pytest.mark.skipif(
+ not td.safe_import("openpyxl"), reason="no openpyxl")),
  pytest.param(None, marks=pytest.mark.skipif(
  not td.safe_import("xlrd"), reason="no xlrd")),
  ])
- def cd_and_set_engine(self, request, datapath, monkeypatch):
+ def cd_and_set_engine(self, request, datapath, monkeypatch, read_ext):
  """
  Change directory and set engine for read_excel calls.
  """
+ if request.param == 'openpyxl' and read_ext == '.xls':
+ pytest.skip()
  func = partial(pd.read_excel, engine=request.param)
  monkeypatch.chdir(datapath("io", "data"))
  monkeypatch.setattr(pd, 'read_excel', func)
@@ -397,6 +401,9 @@ def test_date_conversion_overflow(self, read_ext):
  [1e+20, 'Timothy Brown']],
  columns=['DateColWithBigInt', 'StringCol'])
 
+ if pd.read_excel.keywords['engine'] == 'openpyxl':
+ pytest.xfail("Maybe not supported by openpyxl")
+
  result = pd.read_excel('testdateoverflow' + read_ext)
  tm.assert_frame_equal(result, expected)
 
@@ -724,6 +731,8 @@ class TestExcelFileRead:
  # Add any engines to test here
  pytest.param('xlrd', marks=pytest.mark.skipif(
  not td.safe_import("xlrd"), reason="no xlrd")),
+ pytest.param('openpyxl', marks=pytest.mark.skipif(
+ not td.safe_import("openpyxl"), reason="no openpyxl")),
  pytest.param(None, marks=pytest.mark.skipif(
  not td.safe_import("xlrd"), reason="no xlrd")),
  ])