Python nested loop not working as intended

Question

I'm working on an assignment for school where I have a text file: data.txt which looks like this:(instead of 'name' there are actual names I just replaced them here)

10001-31021 'name'    2015.12.30.   524432

10001-31121 'name'  2016.03.21. 765432

10012-34321 'name'  2016.02.20. 231231

10201-11021 'name'  2016.01.10. 2310456

And I have an update.txt which looks like this:

2016.03.22.
10001-31021 'name'  +20000

10012-34321 'name'  +35432

10012-34321 'name'  -10000

10120-00123 'name'  +120334

10001-31021 'name'  +5000

10210-41011 'name'  -6000

10201-11021 'name'  +100210

12345-32100 'name'  +123456

And I have to make a newdata.txt file according to the changes to the last column that update.txt includes.

This is my code so far:

adat = open("data.txt", "r")
newdata = open("newdata.txt", "w")
update = open("update", "r")

date = update.readline().decode("utf-8-sig").encode("utf-8").splitlines()
num_lines = sum(1 for line in open('update'))
elsociklus = 0
masodikciklus = 0

for num_lines in update:
    updateData = re.search("(.{11}\t)(\D+\t)([+-]\d+)", num_lines)
    elsociklus = elsociklus + 1
    print("elsociklus: " + str(elsociklus))
    for j in adat:
        data = re.search("(.{11}\t)(\D+\t)(\d{4}\.\d{2}\.\d{2}\.\t)(\d+)", j)
        masodikciklus = masodikciklus + 1
        print("masodikciklus: " + str(masodikciklus))
        if data != None:
            if updateData.group(1) == data.group(1):
                print("regi: " + data.group(0))
                print("update: " + updateData.group(0))
                print("uj: " + data.group(1) + data.group(2) + date[0] + "\t" + str(int(data.group(4)) + int(updateData.group(3))))
                newdata.write(data.group(1) + data.group(2) + date[0] + "\t" + str(int(data.group(4)) + int(updateData.group(3))))
                newdata.write("\n")
            else:
                print("nincs valtozas: " + data.group(0))

adat.close()
newdata.close()
update.close()

My problem is with the nested loop. I just can't figure it out why it isn't entering the inner loop for the second time. It works perfectly on the first iteration but when entering the 2nd one in the outer loop it just ignores the inner loop.

Thank you in advance for your help.

Answer 1

Thanks to codingCat for the answer. I fixed the problem by returning my file pointer to the beginning of my file in the inner loop