ID,Name,Gender
1,Smith,M
2,John,M

name,gender,city,id

name,gender,city,id  # name,gender,and id are the only matching columns btw   df1 and df2
Smith,M, ,1          # the data copied for name, gender, and id columns
John,M, ,2

import pandas as pd

f1_df = pd.read_csv("file1.csv")
f2_df = pd.read_csv("file2.csv")

for i in f1_df:
    for j in f2_df:
        i = i.lower()
        if i == j:
            joined = f1_df.join(f2_df)
print joined