datetimeindex

You can add parameters left_index=True and right_index=True if you need merge by indexes in function merge: merge=pd.merge(df,d, how=’inner’, left_index=True, right_index=True) Sample (first value of index in d was changed for matching): print df catcode_amt type feccandid_amt amount date 1915-12-31 A5000 24K H6TX08100 1000 1916-12-31 T6100 24K H8CA52052 500 1954-12-31 H3100 24K S8AK00090 1000 1985-12-31 J7120 … Read more