Python-сообщество

 with open('1.txt') as file_1 , open('2.txt') as file_2:
    list_file_1 = [i.strip() for i in file_1.readlines()]
    list_file_2 = [i.strip() for i in file_2.readlines()]
list_3 = []
for i in list_file_1:
    elem = i[i.find(';')+1:]
    for j in list_file_2:
        if elem in j:
            list_3.append ('{};{}'.format(i.split(';')[0],j.split(';')[-1]))
with open('3.txt','w') as file_3:
    for i in list_3:
        file_3.write(i+'\n')

 import pandas as pd
f1=pd.read_csv("f1.txt",delimiter=";",header=None)
f1.columns=["name","i1","i2"]
f2=pd.read_csv("f2.txt",delimiter=";",header=None)
f2.columns=["i1","i2","name"]
print(pd.merge(f1,f2,on=["i1","i2"]))
>>>         name_x      i1       i2    name_y
         0   Светлана    7250   924    RRR
         1     Игорь  756758  7538    TTT

 Светлана    7250   924    RRR
 Игорь  756758  7538    TTT

 Андрей;QQQ
Светлана;RRR
Игорь;TTT

 res = 'Светлана    7250   924    RRR'.split()
print('{};{}'.format(res[0],res[-1]))

 res[['name_x','name_y']]

 list_file_1 = [i.strip() for i in file_1.readlines()]

 list_file_1 = file_1.read().split()

 if elem in j

 ([a,i1,i2],[b,i1,i2])