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.