CODEWITHSUNDEEP
pythonpandasdataframemapping
Hal
Hal

Reputation: 372

Map dataframe values to index of a list

I've factorized my previous dataframe using this code

df['name'], mapping = df['name'].factorize()

Now I am trying to get the same factorized value for my new dataframe using the variable mapping

Mapping 

Index(['Ranny','Bob','Timmy','Lisa'],
  dtype='object')

My new dataframe

╔════════════════╗
║ Name    Apples ║
╠════════════════╣
║ Lisa      5    ║
║ Timmy     3    ║  
║ Lisa      2    ║
║ Bob       1    ║
╚════════════════╝

The dataframe I want after mapping the column name to the list

╔════════════════╗
║ Name    Apples ║
╠════════════════╣
║ 3         5    ║
║ 2         3    ║  
║ 3         2    ║
║ 1         1    ║
╚════════════════╝

I'm not sure how to do it. I tried to a loop but it takes too much time when the dataset is big. Is there an efficient way to do this?

Upvotes: 1

Views: 58

Answers (1)

anky
anky

Reputation: 75080

If I understand correctly , you can use pd.Index.get_Indexer here:

df2['Name'] = mapping.get_indexer(df2['Name'])
print(df)

   Name  Apples
0     3       5
1     2       3
2     3       2
3     1       1

Upvotes: 3

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