Python：如何在比较其他列时将列值填充到另一个 dataframe 中的新列？

Question

Have got two dataframe

df

Store   Sku     Fixture
11      AA      Product
12      BB      Tier

df1

Store   Sku     Bit
11      AA      1
11      AA      2
12      CC      1
12      CC      2
12      CC      3

So, comparing the 'Store' column from dataframes, need to populate 'Fixture' column in df1 from df. Expected Output:

Store   Sku     Bit     Fixture
11      AA      1       Product
11      AA      2       Product
12      CC      1       Tier
12      CC      2       Tier
12      CC      3       Tier

Thanks in Advance!

Answer 1

You are using dataframes as a relational database. This can be achieved using Series.map

First, build a dictionary holding the relation used for the mapping:

map_dict = df.set_index('Store')['Fixture'].to_dict()

set_index uses a column as row labels. By default, it does not modify the original DataFrame .

Then, we use this dict for a mapping of the 'Store' Series , and append the output to df1 :

df1['Fixture'] = df1['Store'].map(map_dict)