How To Remove A Value From A List In A Pandas Dataframe?

I have created a dataframe: [in] testing_df =pd.DataFrame(test_array,columns=['transaction_id','product_id']) # Split the product_id's for the testing data testing_df.set_index(['

Solution 1:

I would do it before splitting:

Data:

In [269]: df
Out[269]:
                 product_id
transaction_id
1                       P01
2                   P01,P02
3               P01,P02,P09
4                   P01,P03
5               P01,P03,P05
6               P01,P03,P07
7               P01,P03,P08
8                   P01,P04
9               P01,P04,P05
10              P01,P04,P08

Answer :

In [271]: df['product_id'] = df['product_id'].str.replace(r'\,*?(?:P04|P08)\,*?', '') \
                                             .str.split(',')

In [272]: df
Out[272]:
                     product_id
transaction_id
1                         [P01]
2                    [P01, P02]
3               [P01, P02, P09]
4                    [P01, P03]
5               [P01, P03, P05]
6               [P01, P03, P07]
7                    [P01, P03]
8                         [P01]
9                    [P01, P05]
10                        [P01]

alternatively you can change:

testing_df['product_id'] = testing_df['product_id'].apply(lambda row: row.split(','))

with:

testing_df['product_id'] = testing_df['product_id'].apply(lambda row: list(set(row.split(','))- set(['P04','P08'])))

Demo:

In [280]: df.product_id.apply(lambda row: list(set(row.split(','))- set(['P04','P08'])))
Out[280]:
transaction_id
1               [P01]
2          [P01, P02]
3     [P09, P01, P02]
4          [P01, P03]
5     [P01, P03, P05]
6     [P07, P01, P03]
7          [P01, P03]
8               [P01]
9          [P01, P05]
10              [P01]
Name: product_id, dtype: object

Solution 2:

store all your elements to be removed in a list.

remove_results = ['P04','P08']
for k in range(len(testing_df['product_id'])):
    for r in remove_results:
        if r in testing_df['product_id'][k]:
            testing_df['product_id][k].remove(r)

Solution 3:

A list comprehension will likely be most efficient:

exc = {'P04', 'P08'}
df['product_id'] = [[i for i in L if i not in exc] for L in df['product_id']]

Note that an inefficient Python-level loop is unavoidable. apply + lambda, map + lambda or an in-place solution all involve a Python-level loop.