Python Merging Dataframes using multiple Columns

Question

I have 2 dataframes that l need to merge intersecting multiple columns. I'm not getting the results l need as the resulting dataframe has mismatched dates.

I want to merge a pair of columns Date & Segment from dataframe1 to (tmcN & date) | (tmcP & date) from dataframe2 as common columns. Specifically column Segment will match either tmcN or tmcP while at the same time the Date column will be matched to date. I've tried several different ways and can't configure it properly.

My Code:

left2 = Speed.rename({'key':'Segment'}, axis=1)
right2 = Incident.rename({'key':'tmcN'}, axis=1)

Test = left2.merge(right2, left_on='Segment', right_on='tmcN', how='outer')

This only matches Segment to tmcN and my laptop crashes when trying to double merge Segment to tmcP. Thank you for the assistance.

Answer 1

You could try this ( assuming that df1 is the first dataframe and df2 is the second dataframe )

1. Using tmcN of the second dataframe

    df = pd.merge(df1, df2, left_on=['Date', 'Segment'], right_on=['date', 'tmcN'])

2. Using tmcP of the second dataframe

    df = pd.merge(df1, df2, left_on=['Date', 'Segment'], right_on=['date', 'tmcP'])