Error with Python For Loop within Function

Question

So I am trying to better understand functions and using for loops to select from multiple lists. Here is the basic function that I created and it does work:

def my_function(person, feeling):
    print('Hello, %s, how are you? It seems that you are feeling %s!' %(person, feeling))

my_function('Matthew', 'rejuvinated')

But to take this further, I would like to pick a name and a feeling from their respective lists and insert them into the new function. When I try the following, I get an error. Any help would be greatly appreciated!

people = ['Colby', 'Hattie', 'Matthew', 'Stephen', 'Lee', 'Deb', 'Sharon', 'Pete']
feelings = ['happy', 'sad', 'cold', 'cranky', 'happy', 'successful', 'spunky', 'warm', 'nerdy']

def my_function(person, feeling): 
    """This function produces a statement which inserts a name and a feeling"""
    for p in enumerate(people):
            person = p
    for f in enumerate(feelings):
            feeling = f
    print('Hello, %s, how are you? It seems that you are feeling %s!' %(person, feeling)) 
    return my_function()

my_function(people, feelings)

Hello, (7, 'Pete'), how are you? It seems that you are feeling (8, 'nerdy')!
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-1-2b2a265c427c> in <module>
     11     return my_function()
     12 
---> 13 my_function(people, feelings)

<ipython-input-1-2b2a265c427c> in my_function(person, feeling)
      9             feeling = f
     10     print('Hello, %s, how are you? It seems that you are feeling %s!' %(person, feeling))
---> 11     return my_function()
     12 
     13 my_function(people, feelings)

TypeError: my_function() missing 2 required positional arguments: 'person' and 'feeling'

return my_function() your function accept two argument, but you are calling with no arguement — Charif DZ
– Charif DZ, Commented Oct 26, 2019 at 11:18
Please keep in mind I am a "somewhat beginner" (although the question posted here may show my cards). I want to select one name from the first list people and one feeling from the second feelings, produce the sentence Hello Matthew, how are you? It seems that you are feeling nerdy!. I figured enumerate was the way to go but I guess not? — Matt_Davis
– Matt_Davis, Commented Oct 26, 2019 at 11:40
Have a look at my answer and if it suites yous needs I would be glad if you accepted it. — Matthias
– Matthias, Commented Oct 26, 2019 at 11:46

Charif DZ · Accepted Answer · 2019-10-26 12:26:07Z

1

Two loop over two list in the same time use, zip :

peoples = ['Colby', 'Hattie', 'Matthew', 'Stephen', 'Lee', 'Deb', 'Sharon', 'Pete']
feelings = ['happy', 'sad', 'cold', 'cranky', 'happy', 'successful', 'spunky', 'warm', 'nerdy']

def my_function(persons, feelings):
    """This function produces a statement which inserts a name and a feeling"""
    # python provide a zip built-in function to loop over multiple list in the same time
    for person, feeling in zip(persons, feelings):
        # print the message for every element
        print('Hello, %s, how are you? It seems that you are feeling %s!' %(person, feeling))

my_function(peoples, feelings)

The zip() function takes:

iterables - can be built-in iterables (like: list, string, dict), or user-defined iterables (object that has __iter__ method)

The zip() function returns an iterator of tuples based on the iterable object.

If no parameters are passed, zip() returns an empty iterator

If a single iterable is passed, zip() returns an iterator of 1-tuples. Meaning, the number of elements in each tuple is 1.

If multiple iterables are passed, ith tuple contains ith Suppose, two iterables are passed; one iterable containing 3 and other containing 5 elements. Then, the returned iterator has 3 tuples. It's because iterator stops when shortest iterable is exhaused.

edited Oct 26, 2019 at 12:26

answered Oct 26, 2019 at 11:23

Charif DZ

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1 Comment

Matt_Davis Over a year ago

Well done Charif DZ, thank you for your help. I didn't think of zip(). Much appreciated!

Matthias · Accepted Answer · 2019-10-26 11:50:26Z

1

This is your function and the lists of people and feelings.

def my_function(person, feeling):
    print('Hello, %s, how are you? It seems that you are feeling %s!' %(person, feeling))

people = ['Colby', 'Hattie', 'Matthew', 'Stephen', 'Lee', 'Deb', 'Sharon', 'Pete']
feelings = ['happy', 'sad', 'cold', 'cranky', 'happy', 'successful', 'spunky', 'warm', 'nerdy']

You need to call the function with one person and one feeling. To get all combinations you'll have to loop over the lists.

for person in people:
    for feeling in feelings:
        my_function(person, feeling)

If you want only one random person with a random feeling you can use random.choice.

import random
person = random.choice(people)
feeling = random.choice(feelings)
my_function(person, feeling)

Feel free to combine those solutions. Loop over all names and get a random feeling for each person.

import random
for person in people:
    feeling = random.choice(feelings)
    my_function(person, feeling)

Regarding your use of enumerate

for person in enumerate(people):
    print(person)

enumerate will give you a tuple of index and element. The resulting value is nothing that you will need here.

(0, 'Colby')
(1, 'Hattie')
(2, 'Matthew')
(3, 'Stephen')
(4, 'Lee')
(5, 'Deb')
(6, 'Sharon')
(7, 'Pete')

edited Oct 26, 2019 at 11:50

answered Oct 26, 2019 at 11:45

Matthias

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1 Comment

Matt_Davis Over a year ago

This is awesome, thank you so much for your explanation! At this point I wanted to just get a deeper understanding of assigning a function to a list, but my next step was using random to integrate into the function. Much appreciated!

alec_djinn · Accepted Answer · 2019-10-26 12:09:32Z

What about:

def my_function(person, feeling):
    print(f'Hello, {person}, how are you?'\
          f'It seems that you are feeling {feeling}!')

my_function('Matthew', 'rejuvinated')


def my_function_2(people, feelings, fun): 
    for i, person in enumerate(people):
        fun(person, feelings[i])


people = ['Colby', 'Hattie', 'Matthew', 'Stephen', 'Lee', 'Deb', 'Sharon', 'Pete']
feelings = ['happy', 'sad', 'cold', 'cranky', 'happy', 'successful', 'spunky', 'warm', 'nerdy']
my_function_2(people, feelings, my_function)


Hello, Matthew, how are you?It seems that you are feeling rejuvinated!
Hello, Colby, how are you?It seems that you are feeling happy!
Hello, Hattie, how are you?It seems that you are feeling sad!
Hello, Matthew, how are you?It seems that you are feeling cold!
Hello, Stephen, how are you?It seems that you are feeling cranky!
Hello, Lee, how are you?It seems that you are feeling happy!
Hello, Deb, how are you?It seems that you are feeling successful!
Hello, Sharon, how are you?It seems that you are feeling spunky!
Hello, Pete, how are you?It seems that you are feeling warm!

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