Applying a function to a column in pandas

Question

I am working on the movielens dataset, I would like to create a new column by applying a function , the basic idea is : 1) get corresponding movie id from the ratings_dataframe 2)use this movie id to find the name of the movie from moviesdata_frame 3)and copy this value to the corresponding cell in the ratings dataframe

My code consists of:

def getname(p):
    nm =  movies.loc[movies['movie_id'] == 'p']['title']
    return nm   



ratings['title'] = ratings.apply(lambda row:getname(gg['movie_id']))

The error is :('invalid type comparison', u'occurred at index movie_id')

MaxU - stand with Ukraine · Accepted Answer · 2017-03-15 19:32:21Z

1

You don't need a function for this simple mapping:

ratings_dataframe['title'] = \
    ratings_dataframe['movie_id'].map(movies.set_index('movie_id')['title'])

answered Mar 15, 2017 at 19:32

MaxU - stand with Ukraine

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2 Comments

Gru Over a year ago

Works like charm.

Gru Over a year ago

Is it possible to do the same without using the set_index function ?

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