Introduction to Using Apply/Map in Pandas

This section introduces the concept of applying functions to a Pandas DataFrame using apply/map.


So far you’ve been mainly using filters and basic manipulation through groups or dates. You’ve also covered basic aggregation concepts, such as getting the count of records, or the mean of a certain column.

Sometimes, you may need to apply more complex functions to each record, cell, or column.


Assuming you have a certain function my_magic_fn to be applied to every value of a specific column, you can do the following:

df['my_col'].map(lambda x: my_magic_fn(x))

This applies your magic function to every value in my_col column.

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