CODEWITHSUNDEEP
pythonpandas
panda
panda

Reputation: 625

How to replace column values in one dataframe from other dataframe on condition?

import pandas as pd
df = pd.DataFrame({"A":["foo", "foo", "foo", "bar","Panda", "Panda", "Zootopia", "Zootopia"],"B":[0,1,1,1,0,1,1,1]})
df1 = pd.DataFrame({"A":["foo", "foo", "foo", "bar","Panda", "Panda", "Zootopia", "Zootopia","Toy Story"]})

If column A in df and df1 matches then replace df1 column A by df column B value also count number of values not replaced and take a list of them.

Expected Output

    A
0   0.0
1   1.0
2   1.0
3   1.0
4   0.0
5   1.0
6   1.0
7   1.0
8   Toy Story

Not Replaced Count: 1

Not Replaced DataFrame:

 0  A
     Toy Story

Upvotes: 2

Views: 83

Answers (1)

Joe Patten
Joe Patten

Reputation: 1704

Here is one solution:

num = len(df['A'])
if all(df1['A'][:num]==df['A'][:num]):
    df1['A'][:num] = df['B']

Output for df1:

           A
0          0
1          1
2          1
3          1
4          0
5          1
6          1
7          1
8  Toy Story

If you did not want to alter df1, you could make a copy of it and run the code:

num = len(df['A'])
df1_copy = df1.copy()
if all(df1_copy['A'][:num]==df['A'][:num]):
    df1_copy['A'][:num] = df['B']

Output for df1:

           A
0        foo
1        foo
2        foo
3        bar
4      Panda
5      Panda
6   Zootopia
7   Zootopia
8  Toy Story

Output for df1_copy:

           A
0          0
1          1
2          1
3          1
4          0
5          1
6          1
7          1
8  Toy Story

Upvotes: 1

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