python nested loop using files and if condition not working

Question

I have:

master = open('master.txt', 'r')
transaction = open('transaction.txt', 'r')

master_list = []
employee_list = []


    for line in master:
        # split the line
        record = line.split(',')
        # extract id from record
        emp_id = record[0]
        # add id to list
        employee_list.append(emp_id)

        for li in transaction:
            # split the line
            rec = li.split(',')
            i_d = rec[3]
            print(i_d)

This works as expected and outputs

but if I use an if statement in the nested loop like this:

for li in transaction_file:
            # split the line
            rec = li.split(',')
            i_d = rec[3]
            if i_d == emp_id:
                print(emp_id)

I only get 001 001 001 001 001

why is that?

@akonsu are you trolling, bro?

Steve P.
– Steve P.

2014-07-05 20:47:23 +00:00
Commented Jul 5, 2014 at 20:47 — Steve P.
– Steve P., Commented Jul 5, 2014 at 20:47

DrV · Accepted Answer · 2014-07-05 20:54:28Z

2

You never rewind your transaction file; you go through it once during the first cycle of your master loop.

The structure you have may not be the best possible, but:

for line in master:
    # split the line
    record = line.split(',')
    # extract id from record
    emp_id = record[0]
    # add id to list
    employee_list.append(emp_id)

    transaction.seek(0)
    for li in transaction:
        # split the line
        rec = li.split(',')
        i_d = rec[3]
        print(i_d)

The transaction.seek(0) will rewind you back to the beginning of the file (move the reading position to the start of the file) every time before you iterate through it.

edited Jul 5, 2014 at 20:54

answered Jul 5, 2014 at 20:45

DrV

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