In pandas, how to turn a dataframe into tidy data?

Question

In python and pandas I have a dataframe that I need to turn into tidy data to make charts easier

The original data is like this:

I want to transform into a dataframe, with the transposition of the data and adapting column names:

Please is there a way in python to do this?

Answer 1

Use melt:

out = df.melt('year', var_name='localization', value_name='number_of_tests')

You can also use:

out = df.set_index('year').rename_axis(columns='localization').unstack() \
        .rename('number_of_tests').reset_index()