我想只从excel文件中读取某些列到pandas数据框中。我想通过usecols的列范围来指定这一点，但我遇到了一个错误。将列范围指定为字母的正确方法是什么（是的，我知道我可以提供列索引）？

import pandas as pd
df = pd.read_excel("test.xlsx", usecols="A:AV", header=None)

~/anaconda3/lib/python3.5/site-packages/pandas/io/www.example.com in read_excelexcel.py208 true_values = true_values，false_values = false_values，squeeze = squeeze，--> 209kwds）210 211 (io, sheetname, header, skiprows, skip_footer, index_col, names, parse_cols, parse_dates, date_parser, na_values, thousands, convert_float, has_index_names, converters, dtype, true_values, false_values, engine, squeeze,kwds) 207 skip_footer=skip_footer, converters=converters, dtype=dtype, 208 true_values=true_values, false_values=false_values, squeeze=squeeze, --> 209kwds) 210 211
~/anaconda3/lib/python3.5/site-packages/pandas/io/www.example.com in_parse_excelexcel.py- -> 510kwds）511 512输出[asheetname]= www.example.com（）(self, sheetname, header, skiprows, names, skip_footer, index_col, has_index_names, parse_cols, parse_dates, date_parser, na_values, thousands, convert_float, true_values, false_values, verbose, dtype, squeeze,kwds) 508 squeeze=squeeze, 509 dtype=dtype, --> 510kwds) 511 512 output[asheetname] = parser.read ()
python3.5/site-packages/pandas/io/www.example.com in TextParser（* args，*kwds）1910 """1911 kwds ['engine ']=' python '-> 1912 return TextFileReader（ args，**kwds）1913 1914 parsers.py in TextParser(args,kwds) 1910 """ 1911 kwds['engine'] = 'python' -> 1912 return TextFileReader(args,kwds) 1913 1914
~/anaconda3/lib/python3.5/site-packages/pandas/io/www.example.com ininit（self，f，engine，kwds）762 self. options ['has_index_names']= kwds ['has_index_names'] 763--> 764 self._make_engine（self. engine）765 766 def close（self）（self）（self）parsers.py ininit(self, f, engine,kwds) 762 self.options['has_index_names'] = kwds['has_index_names'] 763 --> 764 self._make_engine(self.engine) 765 766 def close(self):
python3.5/site-packages/pandas/io/www.example.com in_make_engine（self，engine）993 '"c"，"python"，or''"python-fwf"）'. format（994 engine = engine））--> 995 self._engine = klass（self. f，self. options）996 997 def_failover_to_python（self）：parsers.py in _make_engine(self, engine) 993 ' "c", "python", or' ' "python-fwf")'.format( 994 engine=engine)) --> 995 self._engine = klass(self.f,self.options) 996 997 def _failover_to_python(self):
~/anaconda3/lib/python3.5/site-packages/pandas/io/www.example.com ininit（self，f，kwds）1994 #如果指定is，则从self.usecols推断列索引。parsers.py ininit(self, f,**kwds) 1994 # infer column indices from self.usecols if is is specified. 1995 self._col_indices = None -> 1996 self.columns, self.num_original_columns = self._infer_columns() 1997 1998 # Now self.columns has the set of columns that we will process.
~/anaconda3/lib/python3.5/site-packages/pandas/io/www.example.com in_inferred_columns（self）2387 else：parsers.py2391如果self. usecols为None或len（names）>= num_original_columns： 2388 columns = [lrange(ncols)] -> 2389 columns = self._handle_usecols(columns, columns[0]) 2390 else: 2391 if self.usecols is None or len(names) >= num_original_columns:
~/anaconda3/lib/python3.5/site-packages/pandas/io/www.example.com in_handle_usecols（self，columns，usecols_key）2422 for col in self. usecols：parsers.py- > 2424 col_indices. append（usecols_key. index（col））2425 2423 if isinstance(col, string_types): -> 2424 col_indices.append(usecols_key.index(col)) 2425
else：2426 col_indices. append（col）

In [20]: pd.__version__
Out[20]: '0.20.2'

文件：test.xlsx