I have a database which has two columns with unique numbers. This is my reference dataframe (df_reference). In another dataframe (df_data) I want to get the rows of this dataframe of which a column values exist in this reference dataframe. I tried stuff like:

df_new = df_data[df_data['ID'].isin(df_reference)]

However, like this I can't get any results. What am I doing wrong here?

CodePudding user response：

From what I see, you are passing the whole dataframe in .isin() method. Try:

df_new = df_data[df_data['ID'].isin(df_reference['ID'])]

CodePudding user response：

Convert the ID column to the index of the df_data data frame. Then you could do

matching_index = df_reference['ID']
df_new = df_data.loc[matching_index, :]

This should solve the issue.