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'