Plotting Series/DF of dtype object fails intermittently #3108
Description
There seems to be an intermittent issue which prevents plotting Series/DataFrames with dtype object. See traceback below. This manifests for me when reading data from files but not when manually creating dataframes from the command line. It can be worked around by explicitly casting to float64. The presence of NANs does not appear to have an effect.
>>> df = pd.read_csv('data.csv') # CSV data file with some "NAN" entries >>> df['chan1'].dtype dtype('object') >>> df['chan1'].plot() # fails >>> df['chan1'].dropna().plot() # fails >>> df['chan1'].apply(float).plot() # works >>> df['chan1'].dropna().apply(float).plot() # worksThis works though:
df = pd.DataFrame([3, 1, 4, np.nan, 5, 9], dtype=object) # works df = pd.DataFrame([3, 1, 4, "NAN", 5, 9], dtype=object) # works df = pd.DataFrame([3, 1, 4, 1, 5, 9], dtype=object) # worksHere is the traceback; it is the same as encountered in #478 and presumably in #1818. Note it doesn't include the error message added in 9186cbc
>>> df = pd.read_csv(r'C:\test\stats.dat') >>> df['Ts_Avg'].plot() Traceback (most recent call last): File "<stdin>", line 1, in <module> File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\pandas\tools\plotting.py", line 1534, in plot_series plot_obj.generate() File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\pandas\tools\plotting.py", line 735, in generate self._make_plot() File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\pandas\tools\plotting.py", line 1106, in _make_plot newline = plotf(*args, **kwds)[0] File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\matplotlib\axes.py", line 3996, in plot for line in self._get_lines(*args, **kwargs): File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\matplotlib\axes.py", line 330, in _grab_next_args for seg in self._plot_args(remaining, kwargs): File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\matplotlib\axes.py", line 289, in _plot_args linestyle, marker, color = _process_plot_format(tup[-1]) File "C:\WinPython-64bit-2.7.3.3\python-2.7.3.amd64\lib\site-packages\matplotlib\axes.py", line 96, in _process_plot_format if fmt.find('--')>=0: AttributeError: 'numpy.ndarray' object has no attribute 'find'