How to subtract rows of one pandas data frame from another?

Question

The operation that I want to do is similar to merger. For example, with the inner merger we get a data frame that contains rows that are present in the first AN

Answer 1

I suggest using parameter 'indicator' in merge. Also if 'on' is None this defaults to the intersection of the columns in both DataFrames.

new = df1.merge(df2,how='left', indicator=True) # adds a new column '_merge'
new = new[(new['_merge']=='left_only')].copy() #rows only in df1 and not df2
new = new.drop(columns='_merge').copy()

    Team    Year    foo
0   Hawks   2001    5
1   Hawks   2004    4
2   Nets    1987    3
4   Nets    2001    8
5   Nets    2000    10

Reference: https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.merge.html

indicator : boolean or string, default False

If True, adds a column to output DataFrame called “_merge” with information on the source of each row. 
Information column is Categorical-type and takes on a value of 
“left_only” for observations whose merge key only appears in ‘left’ DataFrame,
“right_only” for observations whose merge key only appears in ‘right’ DataFrame, 
and “both” if the observation’s merge key is found in both.