Pandas read_csv and UTF-16
csv, pandas, python-2.7, utf-16
Solution
This is a bug, I think because csv reader was passing back an extra empty line in the beginning. It worked for me on Python 2.7.3 and pandas 0.9.1 if I do:
In [36]: pd.read_csv(BytesIO(fh.read().decode('UTF-16').encode('UTF-8')), sep='\t', header=0)
Out[36]:
<class 'pandas.core.frame.DataFrame'>
Int64Index: 50 entries, 0 to 49
Data columns:
Country 43 non-null values
State/City 43 non-null values
Title 43 non-null values
Date 43 non-null values
Catalogue 43 non-null values
Wikipedia Election Page 43 non-null values
Wikipedia Individual Page 43 non-null values
Electoral Institution in Country 43 non-null values
Twitter 43 non-null values
CANDIDATE NAME 1 43 non-null values
CANDIDATE NAME 2 16 non-null values
dtypes: object(11)
I reported the bug here: https://github.com/pydata/pandas/issues/2418 On github master it unfortunately causes a segfault in the c-parser. We'll fix it.
Now, interestingly: https://softwareengineering.stackexchange.com/questions/102205/should-utf-16-be-considered-harmful ;)
Problem
I have a CSV text file encoded in UTF-16 (so as to preserve Unicode characters when others use Excel) but when doing a read_csv with Pandas 0.9.0, I get this cryptic error: ``` df = pd.read_csv('data.txt',encoding='utf-16',sep='\t',header=0) df.head() --------------------------------------------------------------------------- Exception Traceback (most recent call last) <ipython-input-18-85da1383cd9e> in <module>() ----> 1 df = pd.read_csv('candidates-spanish.txt',encoding='utf-16',sep='\t',header=0) 2 df.head() /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/io/parsers.pyc in read_csv(filepath_or_buffer, sep, dialect, header, index_col, names, skiprows, na_values, keep_default_na, thousands, comment, parse_dates, keep_date_col, dayfirst, date_parser, nrows, iterator, chunksize, skip_footer, converters, verbose, delimiter, encoding, squeeze, **kwds) 248 kdict['delimiter'] = sep 249 --> 250 return _read(TextParser, filepath_or_buffer, kdict) 251 252 @Appender(_read_table_doc) /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/io/parsers.pyc in _read(cls, filepath_or_buffer, kwds) 198 return parser 199 --> 200 return parser.get_chunk() 201 202 @Appender(_read_csv_doc) /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/io/parsers.pyc in get_chunk(self, rows) 853 elif not self._has_complex_date_col: 854 index = self._get_simple_index(alldata, columns) --> 855 index = self._agg_index(index) 856 857 elif self._has_complex_date_col: /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/io/parsers.pyc in _agg_index(self, index, try_parse_dates) 980 arr, _ = _convert_types(arr, col_na_values) 981 arrays.append(arr) --> 982 index = MultiIndex.from_arrays(arrays, names=self.index_name) 983 return index 984 /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/index.pyc in from_arrays(cls, arrays, sortorder, names) 1570 1571 return MultiIndex(levels=levels, labels=labels, -> 1572 sortorder=sortorder, names=names) 1573 1574 @classmethod /Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/site-packages/pandas/core/index.pyc in __new__(cls, levels, labels, sortorder, names) 1254 assert(len(levels) == len(labels)) 1255 if len(levels) == 0: -> 1256 raise Exception('Must pass non-zero number of levels/labels') 1257 1258 if len(levels) == 1: Exception: Must pass non-zero number of levels/labels ``` Reading the data in line-by-line with csv.reader based on this example implies that my data is not incorrectly formatted: ``` from io import BytesIO import csv with open('data.txt','rb') as f: r = f.read().decode('utf-16').encode('utf-8') for l in csv.reader(BytesIO(r),delimiter='\t'): print l ['Country', 'State/City', 'Title', 'Date', 'Catalogue', 'Wikipedia Election Page', 'Wikipedia Individual Page', 'Electoral Institution in Country', 'Twitter', 'CANDIDATE NAME 1', 'CANDIDATE NAME 2'] ['Venezuela', 'N/A', 'President', '10/7/12', 'Hugo Rafael Chavez Frias', 'Hugo Ch\xc3\xa1vez', 'Hugo Ch\xc3\xa1vez', 'Hugo Chavez', 'Hugo Ch\xc3\xa1vez Fr\xc3\xadas', 'Hugo Chavez', 'Hugo Ch\xc3\xa1vez'] ['Venezuela', 'N/A', 'President', '10/7/12', 'Henrique Capriles Radonski', 'Henrique Capriles Radonski', 'Henrique Capriles Radonski', 'Henrique Capriles Radonski', 'Henrique Capriles R.', 'Henrique Capriles', ''] ``` Is there some pre-processing, an addition option in read_csv, or something else that needs to be done before pandas.read_csv can read a utf-16 file? Thanks!