How to store outcome of for loop in a variable in python

Question

I have a function within which I have a for loop that is looking for a certain string, which if true executes a different function. What I can't work out is how to create a variable within which to store the outcome of the for loop. I want to take the outcome (i.e. this function was executed or this string was present) and pass that into another function but I cannot get the variable to remember the outcome. Any help would be greatly greatly appreciated. Thank you

for something in something:
    def a_func():
        
        if this  == 'A':
            func_1()
        if this  == 'B':
            func_2()    
        if this  == 'C':
            func_3()  
        if this  == 'D':
            func_4() 

        return this

    this = a_func()

As mentioned by @Sayse you could simply add return to each of your func_1 to func_4 calls, however based on the code, if your func_1 to func_4 do not return A, B, C or D, then I dont see this code being useful after the first iteration. — SShah
– SShah, Commented Apr 30, 2022 at 22:12
@SShah thanks for your input, you're right it's only useful for one iteration as I know one of the four options will definitely be present and I want to take it's value and do something different the next time the for loop iterates. Do you have any advice for doing that? — Doodling
– Doodling, Commented Apr 30, 2022 at 22:33

sarthakt · Accepted Answer · 2022-04-30 22:31:06Z

1

What you want to do and what you have done do not seem to align well. Currently, your code is poorly written. However, it can be fixed as follows:

def func_1():
    return 1
    
def func_2():
    return 2
    
def func_3():
    return 3
    
def func_4():
    return 4
    
action_for_value = {
    'A': func_1,
    'B': func_2,
    'C': func_3,
    'D': func_4,
}
    
for something in ['A', 'B', 'C', 'D', 'E']:
    print(action_for_value[something]() if something in action_for_value else "Not found!!")

This example stores functions corresponding to values in a dictionary and then basis if the value is present, makes a function call.

Here it is in action.

Some notes about your current code:

Declaring a function inside a for loop is never correct, and has quite a few consequences. Move it outside the for block, and then call the function inside the for block.
You want to assign the value of the func_x to a variable which is either global or at least outside the for loop. Alternatively, you can return from a_func the value from func_x as if this == 'A': return func_1() and then use the return value to assign this.

From the looks of it, I would ask you to review your understanding of the basics of Python. A lot of it seems cobbled together without a good understanding of what is happening.

edited Apr 30, 2022 at 22:31

user964843

answered Apr 30, 2022 at 22:06

sarthakt

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5 Comments

autopoietic Over a year ago

This response is quite aggressively worded. It might be helpful to soften the tone.

Doodling Over a year ago

This worked and I learned a lot thank you so much. What if say, 'A' was the only string present in 'something' and I wanted to pass it's corresponding function onto another function. Would I use the 'A' function as a parameter in the next function?

Doodling Over a year ago

"You want to assign the value of the func_x to a variable which is either global or at least outside the for loop. Alternatively, you can return from a_func the value from func_x as if this == 'A': return func_1() and then use the return value to assign this." - How do I do this in the if statement? would it look like if this == 'A': return func_1() this = func_x() ? "From the looks of it, I would ask you to review your understanding of the basics of Python.." - 100% you're correct, I'm doing my best to learn and understand python basics. I appreciate your input immensely

sarthakt Over a year ago

@autopoietic point taken. will be better with my future answers :)

sarthakt Over a year ago

@Doodling, for > What if say, 'A' was the only string present in 'something' and I wanted to pass it's corresponding function onto another function. Would I use the 'A' function as a parameter in the next function? you could just pass it as some_func(action_for_value['A']) and then in some_func body, you could say def some_func(func_for_A): func_for_A().

BeRT2me · Accepted Answer · 2022-04-30 22:02:59Z

I'm not sure what you're actually trying to do, but defining a function inside of a for loop is definitely not the way to do so.

def func_1():
    pass

def func_2():
    pass

def func_3():
    pass

def func_4():
    pass

def a_func(this):
    if this  == 'A':
        func_1()
        return f'{this} found and func_1() ran.'
    elif this  == 'B':
        func_2()    
        return f'{this} found and func_2() ran.'
    elif this  == 'C':
        func_3()  
        return f'{this} found and func_3() ran.'
    elif this  == 'D':
        func_4() 
        return f'{this} found and func_4() ran.'
    else:
        pass
        

something = ['A', 'B', 'C', 'D']

outputs = [a_func(x) for x in something]

for value in outputs:
    print(value)

Output:

A found and func_1() ran.
B found and func_2() ran.
C found and func_3() ran.
D found and func_4() ran.

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