Python - performing multiple calculations on single arrays?

Question

I have an array that I would like to perform 2 calculations on.

1) I want to take the largest integer not greater than x for every array value, divide that value by 3, then subtract 2.

2) I then want to sum the array values.

Here is my script:

mass = [1,2,3,4,5]

def Multiply(x):
    return (math.floor(x/3) - 2)

for i in mass: 
    new_mass = Multiply(i)

    print(new_mass)

When I run the script it works as expected. I get:

-2 -2 -1 -1 -1

However, when try to sum the new_mass in a "total" variable I get the following error:

total = sum(new_mass)
print(total)

"TypeError: 'int' object is not iterable"

Can someone please help? Below is the complete code:

mass = [1,2,3,4,5]

def Multiply(x):
    return (math.floor(x/3) - 2)

for i in mass: 
    new_mass = Multiply(i)

    print(new_mass)

total = sum(new_mass)
print(total)

Brian · Accepted Answer · 2019-12-23 23:50:22Z

4

new_mass is an integer that gets overwritten with each loop through i.

define your total at the start and sum it as you loop through, then print.

something like:

mass = [1,2,3,4,5]
total = 0 

def Multiply(x):
    return (math.floor(x/3) - 2)

for i in mass: 
    new_mass = Multiply(i)
    total = total + new_mass
    print(new_mass)

print(total)

If you want to write the calculation back to the array it would look something like this: (untested)

mass = [1,2,3,4,5]

def Multiply(x):
    return (math.floor(x/3) - 2)

for i in mass: 
    i = Multiply(i)
    print(i)

print(sum(mass))

edited Dec 23, 2019 at 23:50

answered Dec 23, 2019 at 23:43

Brian

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Comments

shin · Accepted Answer · 2019-12-24 06:05:07Z

0

Is this what you want?

import numpy as np
mass = np.array([1,2,3,4,5])
newmass = mass / 3 - 2
np.floor(newmass).sum()

This returns -7.0.

https://repl.it/@shinokada/stackoverflow001

edited Dec 24, 2019 at 6:05

answered Dec 24, 2019 at 5:59

shin

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