python - ValueError: cannot use inplace with CategoricalIndex -
i using pandas 0.18.
this fails
cat_fields[f[0]].add_categories(s,inplace=true)
however docs say
inplace : boolean (default: false)
whether or not add categories inplace or return copy of categorical added categories.
am missing ?
i creating superset of categories/columns across many dataframes able concatenate them.
my error:
valueerror: cannot use inplace categoricalindex
i think need assign original column, because series.add_categories
has inplace
parameter , works nice.
but in categoricalindex.add_categories
has inplace
parameter, fails. think bug.
cat_fields[f[0]] = cat_fields[f[0]].add_categories(s)
or:
cat_fields[f[0]] = cat_fields[f[0]].cat.add_categories(s)
sample:
cat_fields = pd.dataframe({'a':[1,2,3]}, index=['a','d','f']) cat_fields.index = pd.categoricalindex(cat_fields.index) cat_fields.a = pd.categorical(cat_fields.a) print (cat_fields) a 1 d 2 f 3 s = ['b','c'] cat_fields.a.cat.add_categories(s,inplace=true) print (cat_fields.a) name: a, dtype: category categories (5, object): [1, 2, 3, b, c] cat_fields.index.add_categories(s,inplace=true) print (cat_fields)
valueerror: cannot use inplace categoricalindex
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