dask.dataframe.DataFrame.melt
dask.dataframe.DataFrame.melt¶
- DataFrame.melt(id_vars=None, value_vars=None, var_name=None, value_name='value', col_level=None)[source]¶
Unpivots a DataFrame from wide format to long format, optionally leaving identifier variables set.
This function is useful to massage a DataFrame into a format where one or more columns are identifier variables (
id_vars
), while all other columns, considered measured variables (value_vars
), are “unpivoted” to the row axis, leaving just two non-identifier columns, ‘variable’ and ‘value’.- Parameters
- frameDataFrame
- id_varstuple, list, or ndarray, optional
Column(s) to use as identifier variables.
- value_varstuple, list, or ndarray, optional
Column(s) to unpivot. If not specified, uses all columns that are not set as id_vars.
- var_namescalar
Name to use for the ‘variable’ column. If None it uses
frame.columns.name
or ‘variable’.- value_namescalar, default ‘value’
Name to use for the ‘value’ column.
- col_levelint or string, optional
If columns are a MultiIndex then use this level to melt.
- Returns
- DataFrame
Unpivoted DataFrame.
See also