How to achieve an inner join in pandas

Question

I need to effectively do an inner join implemented in Python.

I have 2 data sets which come from separate sources but share a common key.

Lets say (for the sake of argument) that they look like this:

person_likes = [{'person_id': '1', 'food': 'ice_cream', 'pastimes': 'swimming'},
                {'person_id': '2', 'food': 'paella', 'pastimes': 'banjo'}]

person_accounts = [{'person_id': '1', 'blogs': ['swimming digest', 'cooking puddings']},
                   {'person_id': '2', 'blogs': ['learn flamenca']}]

How best can I join these two sets of data. I have something like this:

joins = []
for like in person_likes:
    for acc in person_accounts:
        if like['person_id'] == acc['person_id']:
            join = {}
            join.update(like)
            join.update(acc)
            joins.append(join)

print(joins)

This appears to work fine (I haven't tested it extensively), and at first glance looks like the best we can do - but I wonder if there is a know algorithm which is more performant and also if there is a more idiomatic or Pythonic way of doing this?

score 4 · Accepted Answer · answered Sep 28 '17 at 15:14

Pandas seems like an obvious answer here.

import pandas as pd
accounts = pd.DataFrame(person_accounts)
likes = pd.DataFrame(person_likes)
pd.merge(accounts, likes, on='person_id')

                             blogs person_id       food  pastimes
# 0  [swimming digest, cooking puddings]         1  ice_cream  swimming
# 1                     [learn flamenca]         2     paella     banjo

How to achieve an inner join in pandas

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