Correlation between two non-numeric columns in a Pandas DataFrame

To quickly get a correlation:

df.apply(lambda x: x.factorize()[0]).corr()

                group  phone_brand
group        1.000000     0.427941
phone_brand  0.427941     1.000000

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Heat map

import seaborn as sns

sns.heatmap(pd.crosstab(df.group, df.phone_brand))