Closed
Description
Code Sample, a copy-pastable example if possible
Given the code sample below:
data_df = pd.DataFrame([{'col_a': '1', 'col_b': '16.5%', 'col_c': 'test'},
{'col_a': '2.2', 'col_b': '15.3', 'col_c': 'another_test'}
])
type_dict = {'col_a': 'float64', 'col_b': 'float64', 'col_c': 'object}
data_df = data_df.astype(dtype=type_dict, errors='ignore')Problem description
Pandas will raise the error ValueError: could not convert string to float: '16.5%' despite the fact that the errors='ignore' parameter was passed in. This is probable due to the implementation of astype, as can be seen in pandas.core.generic.py lines 5658 - 5680
if is_dict_like(dtype):
if self.ndim == 1: # i.e. Series
if len(dtype) > 1 or self.name not in dtype:
raise KeyError('Only the Series name can be used for '
'the key in Series dtype mappings.')
new_type = dtype[self.name]
return self.astype(new_type, copy, errors, **kwargs)
elif self.ndim > 2:
raise NotImplementedError(
'astype() only accepts a dtype arg of type dict when '
'invoked on Series and DataFrames. A single dtype must be '
'specified when invoked on a Panel.'
)
for col_name in dtype.keys():
if col_name not in self:
raise KeyError('Only a column name can be used for the '
'key in a dtype mappings argument.')
results = []
for col_name, col in self.iteritems():
if col_name in dtype:
results.append(col.astype(dtype[col_name], copy=copy))
else:
results.append(results.append(col.copy() if copy else col))Expected Output
One would expect the pd.DataFrame to successfully type cast, leaving the col_b as an np.object type