Jordan S. Jordan S. - 3 years ago 152
Python Question

Counting and Running Totals in Python 3

First time poster here (and pretty much completely new to python) with an undoubtedly easy question. I'll cut to the chase, here's my current code:

def even(x):

if x % 2 == 0:
even = True
even = False

if even is True:

if even is False:


for x in N:

As it is the function takes each input and prints whether it's Even or Odd, very basic.

I gave myself the objective of writing a function/script that will take a list of numbers and spit out something like: "There are 15 even numbers and 8 odd numbers." However, I'm having trouble understanding how to count up a running total of how many times my variable "even" is True or False. Furthermore I don't understand how to then use that variable outside the function. So far my best attempts result in an output like:

There were 1 Odd numbers

There were 1 Odd numbers

There were 1 Even numbers

There were 1 Even numbers

etc... for whatever is in list N.

Whereas what I want is:

There were 2 Odd numbers

There were 2 Even numbers

Can anyone help me learn how to do something like this?

Jan Jan
Answer Source

You can use sum() and map():

def even(x):
    return (x % 2 == 0)   

N = [1,3,2,4,6,8]

n_even = sum(map(even, N))
# 4

Now even returns True (1) if the number is even and False (0) otherwise. Now simply sum it up and you have the times an even number occurred.
Additionally, you might want to define n_odd as

n_odd = len(N) - n_even
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