How can I compare two lists of strings in python?

Question

I am trying to compare two lists of number plates. If the number plate is in both lists I want to print the number plate and the time. And if the number plate only exists once in one of the lists, I want to print "no match". Thanks in advance. The input is like this:

1   12:00:00    45-NK-JX
1   12:00:03    DX-89-EH
1   12:00:09    DG-65-LN
2   12:00:10    RW-MJ-73
1   12:00:11    ZS-24-74
2   12:00:14    07-SD-12
2   12:00:18    GX-62-38
1   12:00:19    09-PQ-23
2   12:00:20    45-NK-JX
1   12:00:20    NG-24-DB

This is my code:

def line_information(line):
if line == '':
    return
sensor_time_plate = line.split()
sensor = sensor_time_plate[0]
time = sensor_time_plate[1]
plate = sensor_time_plate[2]
if sensor == "1":
    global plate_1
    plate_1 = plate



elif sensor == "2":
    global plate_2
    plate_2 = plate

    if set(plate_1) & set(plate_2):
        print(plate)
    else:
        print("No match")

Answer 1

So first we need to read the input. We can use fileinput.input for that, and split the fields with string.split:

import fileinput

set1 = set()
set2 = set()
for line in fileinput.input():
    n, time, plate = line.strip().split("\t")

    if n == "1":
        set1.add(plate)
    else:
        set2.add(plate)

After we build our sets , we can use their methods to find common and distinct elements:

matches = set1.intersection(set2)
plates_only_in_s1 = set1.difference(set2)
plates_only_in_s2 = set2.difference(set1)

print(f"Matched plates: {matches}") # {'45-NK-JX'}
print(f"Plates only in s1: {plates_only_in_s1}") # {'DG-65-LN', '09-PQ-23', 'DX-89-EH', 'NG-24-DB', 'ZS-24-74'}
print(f"Plates only in s2: {plates_only_in_s2}") # {'GX-62-38', '07-SD-12', 'RW-MJ-73'}

Alternatively, you can use an iterative approach:

for plate in set1:
    if plate in set2:
        print("Match: ", plate)
    else:
        print ("No match: ", plate)

for plate in set2:
    if plate not in set1:
        print("No match: ", plate)

Which prints:

No match:  DG-65-LN
No match:  09-PQ-23
No match:  DX-89-EH
No match:  NG-24-DB
Match:  45-NK-JX
No match:  ZS-24-74
No match:  GX-62-38
No match:  07-SD-12
No match:  RW-MJ-73

I added the IDs to make it more obvious which plates match or don't match, but you can remove them if the solutions requires omitting them.