How to apply “first” and “last” functions to columns while using group by in pandas?

Question

I have a data frame and I would like to group it by a particular column (or, in other words, by values from a particular column). I can do it in the following way: gro

Answer 1

I'm not sure if this is really the issue, but sum and min are Python built-ins that take some iterables as input, whereas first is a method of pandas Series object, so maybe it's not in your namespace. Moreover it takes something else as an input (the doc says some offset value).

I guess one way to get around it is to create your own first function, and define it such that it takes a Series object as an input, e.g.:

def first(Series, offset):
    return Series.first(offset)

or something like that..