Pandas - how to compare 2 series and append the values which are in both to a list

Question

I have written code where I have a dataframe containing all types of food. I have then split it into fruit and veg series using str.contains. I have written code where I append any food which is common in both series to a list:

fruit = fruit_2.tolist()#converting the series to a list
veg = veg_2.tolist()#converting the series to a list

for x in range (len(fruit)):
    for y in range (len(veg)):
        if fruit[x] == veg[y]:
            both.append(fruit[x]) 
print(both)

This works just wondering if someone has a solution which utilised pandas and doesn't use a for loop. Thanks

Combine the two series and do: https://stackoverflow.com/questions/14657241/how-do-i-get-a-list-of-all-the-duplicate-items-using-pandas-in-python — xyzjayne, Jul 18 '18 at 14:41
Possible duplicate of [Finding the intersection between two series in Pandas](https://stackoverflow.com/questions/18079563/finding-the-intersection-between-two-series-in-pandas) — moshevi, Jul 18 '18 at 14:44
Possible duplicate of [How to implement 'in' and 'not in' for Pandas dataframe](https://stackoverflow.com/questions/19960077/how-to-implement-in-and-not-in-for-pandas-dataframe) — ALollz, Jul 18 '18 at 14:48

score 0 · Accepted Answer · answered Jul 18 '18 at 14:42

0

Try this:

fruit_2[fruit_2.isin(veg_2)]

This will give you the common elements.

answered Jul 18 '18 at 14:42

Ashish Acharya

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The list is longer than I expected as it returns more values than my previous code, would you say my code is incorrect?. – Harry Maguire Jul 18 '18 at 15:01
No, I think the duplicates are filtered out. If you want to check just to be sure, just do this `c=fruit_2[fruit_2.isin(veg_2)]` and `len(c[c.duplicated(keep=False)]` – Ashish Acharya Jul 18 '18 at 15:03
The length reutrns 0 when i run this, does this mean there are no duplicates? – Harry Maguire Jul 18 '18 at 15:12
Yep. No duplicates. – Ashish Acharya Jul 18 '18 at 15:15

moshevi · Answer 2 · 2018-07-18T15:11:26.493

0

you could use np.intersect1d

import numpy as np

# gives a numpy array (you can later convert to series or list)
both = np.intersect1d(fruit_2, veg_2)

courtesy of this answer

edited Jul 18 '18 at 15:11

answered Jul 18 '18 at 14:42

moshevi

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I think this works, what is the syntax to convert this to a series? – Harry Maguire Jul 18 '18 at 15:00
`both_series = pd.Series(both)` – moshevi Jul 18 '18 at 15:01

Pandas - how to compare 2 series and append the values which are in both to a list

2 Answers2