python nested 'for' loop breaks too soon

Question

I cant spot what is going on here with this nested loop. The inner (for line in temp:) loop runs great but outer for loop (for cnt in range) only runs once, so that temp is only appended to infile once.

with open("temp_inv.ext") as temp:
    with open(infile, 'a') as of:
        for cnt in range(1, sample_cnt):
            for line in temp:
                l = None
                if "INVERSE_MODELING" in line:
                    l = line.replace(smp_num[0], smp_num[cnt])
                if "solutions" in line:
                    l = line.replace(smp_num[0], smp_num[cnt])
                if "netpath" in line:
                    l = line.replace(smp_num[0], smp_num[cnt])
                if l is None:
                    of.write(line)
                else: of.write(l)

I have checked that 'sample_cnt' is an integer and 'smp_num' is a valid array.

What am I missing?

EDIT:

To clarify for others that want to use a similar method -

I want to append 'temp' to 'of' after mangling 'temp' by changing a string based on the 'smp_num' array. Addition of the {temp.seek(0)} answered my problem, I had missed that the outer loop was still inside the {with} statement, thus needed to seek before running again.

Answer 1

You need to use seek() to rewind the file once you read all the lines. Use

temp.seek(0)

somewhere in the outer loop