How do I run a list through a function in python?

Question

I am trying to run my list though a function that I created, but keep getting errors. I don't know what is wrong.

Temperatures in F:

temp_f =  [19, 21, 21, 21, 23]

Function:

def fahrToCelsius(tempFahrenheit):
    return (tempFahrenheit - 32) /1.8 

The function works, eg

fahrToCelsius(temp_f[1])

gives:

-6.111111111111111

But running it though a list doesn't. My attempt:

temp_c = []

for i in temp_f:
    temp_c.append (fahrToCelsius(temp_f[i]))

print(temp_c)

Giving this error:

IndexError: list index out of range

I have tried a few different things, but nothing that I have tried works. Do you have any tips? Thanks.

Answer 1

最pythonic的解决方案是使用列表理解：

temp_c = [fahrToCelsius(t) for t in temp_f]

Answer 2

for i in temp_f is actually assigning i to each element in your array, so 19, 21, etc. Therefore, temp_f[i] is actually temp_f[19] , which is why you are getting the error. Change the loop to:

for i in range(0, len(temp_f)):
    temp_c.append (fahrToCelsius(temp_f[i]))

or instead:

for temp in temp_f:
    temp_c.append (fahrToCelsius(temp))

Answer 3

Iterating the list using for i in temp_f makes i in this context refer to every item in your list.

What you want to do is iterate the list indices instead, like for i in range(len(temp_f)) .

Alternatively, you can iterate the list items like you did, but pass i as the parameter to fahrToCelsius (instead of temp_f[i] ).

Answer 4

If you want to use list as an input for this question as you are trying then use a numpy array instead of list , it will broadcast your conversion

import numpy as np
Lis= np.array([30,40,50])
def fahrToCelsius(tempFahrenheit):
    return (tempFahrenheit - 32) /1.8
print(fahrToCelsius(Lis))