Merge two python pandas data frames of different length but keep all rows in output data frame

Question

I have the following problem: I have two pandas data frames of different length containing some rows and columns that have common values and some that are different, like this:<

Answer 1

Looks like you're looking for something like a left-join. See if this example helps: http://pandas.pydata.org/pandas-docs/stable/comparison_with_sql.html#left-outer-join

You can basically pass a parameter to merge() called how='left'

Answer 2

You can simply use merge with using on and list as well

result = df1.merge(df2, on=['Column1'])

For more information follow link

Answer 3

You can read the documentation here: http://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.merge.html

What you are looking for is a left join. The default option is an inner join. You can change this behavior by passing a different how argument:

df1.merge(df2,how='left', left_on='Column1', right_on='ColumnA')