For Loop Within an If Statement Python

Question

I am using a for-loop within another for-loop to iterate through and compare two data sets. I want to first use the inner for loop to check for a condition and then, if it fails, to print a value from the outer loop.

For example:

for (i) in list_one:

    for (j) in list_two:
        
        if (condition):

            print(j)

if the condition for 'print(j)' fails for all instances in list_two, I want the current value of list_one to be printed. Something like an 'if: for:' statement seems like it would make sense but I'm not sure if those are possible in Python. Thanks for the help

If the condition is true for some j, do you want to continue checking/printing the remaining js? — Kelly Bundy
– Kelly Bundy, Commented Mar 14, 2022 at 7:00

wogsland · Accepted Answer · 2022-03-14 06:57:21Z

2

You can just add a fail flag, like

for (i) in list_one:
    fail = True
    for (j) in list_two:
        if (condition):
            fail = False
            print(j)
    if fail:
        print(i)

answered Mar 14, 2022 at 6:57

wogsland

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1 Comment

sotired Over a year ago

Thanks! That worked perfectly. I will accept the answer in 4 minutes when stack overflow allows me to

Shivam Agrawal · Accepted Answer · 2022-03-14 07:01:55Z

0

If you need to print only the first satisfy condition and then break out of the loop, then you can use for ... else

for (i) in list_one:
    for (j) in list_two:
        if (condition):
            print(j)
            break
    else:
        print(i)

If you want to print all the values which satisfy the condition in inner loop, you can use one more variable

for (i) in list_one:
    print_i = True
    for (j) in list_two:
        if (condition):
            print(j)
            print_i = False
    if print_i:
        print(i)

answered Mar 14, 2022 at 7:01

Shivam Agrawal

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