BUG: formatters argument to DataFrame.to_latex() is broken #6052
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Description
It appears that neither the formatters nor float_format arguments to DataFrame.to_latex work if changed from their default values. Both raise the same exception: AttributeError: 'numpy.float64' object has no attribute 'decode'.
Note: neither of these arguments has test coverage in pandas/tests/test_format.py
My test script:
In [1]: from pandas.util.print_versions import show_versions
In [2]: show_versions()
INSTALLED VERSIONS
------------------
Python: 2.7.5.final.0
OS: Darwin
Release: 13.0.0
Processor: i386
byteorder: little
LC_ALL: None
LANG: en_US.UTF-8
pandas: 0.13.0
Cython: 0.19.2
Numpy: 1.8.0
Scipy: 0.13.1
statsmodels: Not installed
patsy: 0.2.1
scikits.timeseries: Not installed
dateutil: 2.2
pytz: 2013.9
bottleneck: 0.7.0
PyTables: Not Installed
numexpr: 2.1
matplotlib: 1.3.1
openpyxl: Not installed
xlrd: Not installed
xlwt: Not installed
xlsxwriter: Not installed
sqlalchemy: 0.7.5
lxml: Not installed
bs4: Not installed
html5lib: Not installed
bigquery: Not installed
apiclient: 1.0c1
In [3]: import pandas as pd
In [4]: df = pd.DataFrame({'a': [1.0, 2.0]})
In [5]: df.to_latex()
Out[5]: u'\\begin{tabular}{lr}\n\\toprule\n{} & a \\\\\n\\midrule\n0 & 1 \\\\\n1 & 2 \\\\\n\\bottomrule\n\\end{tabular}\n'
In [6]: df.to_latex(float_format=lambda x: x)
---------------------------------------------------------------------------
AttributeError Traceback (most recent call last)
<ipython-input-6-c932ce2a22b5> in <module>()
----> 1 df.to_latex(float_format=lambda x: x)
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/frame.pyc in to_latex(self, buf, columns, col_space, colSpace, header, index, na_rep, formatters, float_format, sparsify, index_names, bold_rows, force_unicode)
1381 sparsify=sparsify,
1382 index_names=index_names)
-> 1383 formatter.to_latex()
1384
1385 if buf is None:
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in to_latex(self, force_unicode, column_format)
446 strcols = [[info_line]]
447 else:
--> 448 strcols = self._to_str_columns()
449
450 if column_format is None:
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in _to_str_columns(self)
325 stringified = []
326 for i, c in enumerate(cols_to_show):
--> 327 fmt_values = self._format_col(i)
328 cheader = str_columns[i]
329
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in _format_col(self, i)
490 (self.frame.iloc[:self.max_rows_displayed, i]).get_values(),
491 formatter, float_format=self.float_format, na_rep=self.na_rep,
--> 492 space=self.col_space
493 )
494
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in format_array(values, formatter, float_format, na_rep, digits, space, justify)
1615 justify=justify)
1616
-> 1617 return fmt_obj.get_result()
1618
1619
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in get_result(self)
1733 fmt_values = self._format_with(fmt_str)
1734
-> 1735 return _make_fixed_width(fmt_values, self.justify)
1736
1737
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in _make_fixed_width(strings, justify, minimum, truncated)
1795 _strlen = _strlen_func()
1796
-> 1797 max_len = np.max([_strlen(x) for x in strings])
1798
1799 if minimum is not None:
/Users/shoyer/dev/climatology-research/library/python/target/climatology/lib/python2.7/site-packages/pandas/core/format.pyc in _strlen(x)
227 def _strlen(x):
228 try:
--> 229 return len(x.decode(encoding))
230 except UnicodeError:
231 return len(x)
AttributeError: 'numpy.float64' object has no attribute 'decode'