Filtering dataframe in pandas based on a list of strings

Question

I have started exploring pandas recently, I am trying to import a list of fruits from sector.py and use it as a filter to produce a table of items where only fruits within the list are displayed. I am not getting the output desired is there something wrong with my codes?

Within sector.py

Fruits=['Apple','Orange','Pineapples']

Within calculator.py

import sector
import pandas as pd

pdmart = pd.read_csv('supermarket.csv')
pdextract = pdmart.groupby('item')['price'].sum()

Fruits = pdextract[pdextract.isin(sector.Fruits)]
print Fruits

Current output:

Series([], Name: price, dtype: float64)

Desired output:

Item         Price
Apple        12.0
Orange       7.0
Pineapples   15.0

or reindex with the list after the groupby, which will ensure you display NaN for groups you are missing completely. — ALollz
– ALollz, Commented Sep 28, 2018 at 17:06

jpp · Accepted Answer · 2018-09-28 16:55:29Z

3

Applying isin on a GroupBy object doesn't make sense. You can use Boolean indexing on the index of your GroupBy object:

Fruits = pdextract[pdextract.index.isin(sector.Fruits)]

You can also filter on a series before your GroupBy operation:

pdextract = pdmart.loc[pdmart['item'].isin(sector.Fruits)]\
                  .groupby('item')['price'].sum()

answered Sep 28, 2018 at 16:55

jpp

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6 Comments

Sam T Over a year ago

Hi! Thank you for your reply, could you explain a little more on why I can't group them before apply isin on the groupings?

jpp Over a year ago

@SamT, You can. My first solution is after the GroupBy. Notice pdextract is the GroupBy object as in your question.

Sam T Over a year ago

cool! thank you! also, if i were to sum up the values of all the fruits, could I do a .sum() again on the variable pdextract? Meaning to say: Fruits 34.0 Apologies if i am vague, this is my first language..

jpp Over a year ago

@SamT, Sure, give it a go. But if you have a new question, you should ask a new question. This isn't a forum.

ubuntu_noob Over a year ago

@jpp this is because after doing pdextract = pdmart.groupby('item')['price'].sum() the groupby column becomes the default index column right?

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