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

• s510: can you share the output/error you are getting now?
• Kelly Bundy: If the condition is true for some j, do you want to continue checking/printing the remaining js?

Answer 1

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)

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

Answer 2

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)