list - Identifying coordinate matches from two files using python -

i've got 2 sets of data describing atomic positions. they're in separate files compare, aim being identifying matching atoms coordinates. data looks following in both cases, , there's going 1000 or entries. files of different lengths since describe different sized systems , have following format:

   1   ,    0.000000000000e+00  0.000000000000e+00        2   ,   0.000000000000e+00  2.468958660000e+00      3   ,    0.000000000000e+00 -2.468958660000e+00      4   ,   2.138180920454e+00 -1.234479330000e+00      5   ,    2.138180920454e+00  1.234479330000e+00 

the first column entry id, second set of coordinates in x,y.

what i'd compare coordinates in both sets of data, identify matches , corresponding id eg "entry 3 in file 1 corresponds entry 6 in file 2." i'll using information alter coordinate values within file 2.

i've read files, line line , split them 2 entries per line using command, put them list, bit stumped how specify comparison bit - particularly telling compare second entries only, whilst being able call first entry. i'd imagine require looping ?

code looks far:

open1 = open('./3x3supercell_coord_clean','r') opena = open('./6x6supercell_coord_clean','r')  small_list=[]  line in open1:     stripped_small_line = line.strip()     column_small = stripped_small_line.split(",")      small_list.append(column_small)  big_list=[]  line in opena:     stripped_big_line = line.strip()     column_big = stripped_big_line.split(",")     big_list.append(column_big)  print small_list[2][1] #prints out coords 

if doing trying compare second element of each element in 2 lists, can done having each coord compared against each coord in opposite file. not fastest way go it, should results need.it scans through small list, , checks every small_entry[1] (the coordinate) against every coordinate each entry in big_list

for small_entry in small_list:     big_entry in big_list:         if small_entry[1] == big_entry[1] :             print(small_entry[0] + "matches" +  big_entry[0]) 

something this?