Reshaping with melt

Reshaping Data with pandas

Maria Eugenia Inzaugarat

Data Scientist

Wide to long transformation

Perform analytics
Plot different variables in the same graph

Wide to long transformation

Melt

Melting data

books

                             title isbn language pages
0                  Mostly Harmless  074      eng   260
1           The Hitchhiker's Guide  072      eng   215
2 El restaurante del fin del mundo  071      spa   250

books.melt(id_vars='title')

                              title  variable   value
0                   Mostly Harmless      isbn     074
1            The Hitchhiker's Guide      isbn     072
2  El restaurante del fin del mundo      isbn     071
3                   Mostly Harmless  language     eng
4            The Hitchhiker's Guide  language     eng
5  El restaurante del fin del mundo  language     spa
6                   Mostly Harmless     pages     260
7            The Hitchhiker's Guide     pages     215
8  El restaurante del fin del mundo     pages     250

Values and variables

Specifying values to melt

books.melt(id_vars='title', value_vars=['language_code', 'num_pages'])

                              title  variable   value
0                   Mostly Harmless  language     eng
1            The Hitchhiker's Guide  language     eng
2  El restaurante del fin del mundo  language     spa
3                   Mostly Harmless     pages     260
4            The Hitchhiker's Guide     pages     215
5  El restaurante del fin del mundo     pages     250

Naming values and variables

books.melt(id_vars='title', value_vars=['language_code', 'isbn'], var_name='feature', value_name='code')

                              title   feature    code
0                   Mostly Harmless      isbn     074
1            The Hitchhiker's Guide      isbn     072
2  El restaurante del fin del mundo      isbn     071
3                   Mostly Harmless  language     eng
4            The Hitchhiker's Guide  language     eng
5  El restaurante del fin del mundo  language     spa

Let's practice!

Reshaping Data with pandas