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How do you divide each element in a list by an int?


Question

I just want to divide each element in a list by an int.

myList = [10,20,30,40,50,60,70,80,90]
myInt = 10
newList = myList/myInt

This is the error:

TypeError: unsupported operand type(s) for /: 'list' and 'int'

I understand why I am receiving this error. But I am frustrated that I can't find a solution.

Also tried:

newList = [ a/b for a, b in (myList,myInt)]

Error:

ValueError: too many values to unpack

Expected Result:

newList = [1,2,3,4,5,6,7,8,9]


EDIT:

The following code gives me my expected result:

newList = []
for x in myList:
    newList.append(x/myInt)

But is there an easier/faster way to do this?

2015/10/22
1
155
10/22/2015 9:23:19 PM

Accepted Answer

The idiomatic way would be to use list comprehension:

myList = [10,20,30,40,50,60,70,80,90]
myInt = 10
newList = [x / myInt for x in myList]

or, if you need to maintain the reference to the original list:

myList[:] = [x / myInt for x in myList]
2014/10/09
236
10/9/2014 10:02:02 PM

The way you tried first is actually directly possible with numpy:

import numpy
myArray = numpy.array([10,20,30,40,50,60,70,80,90])
myInt = 10
newArray = myArray/myInt

If you do such operations with long lists and especially in any sort of scientific computing project, I would really advise using numpy.

2014/10/30

>>> myList = [10,20,30,40,50,60,70,80,90]
>>> myInt = 10
>>> newList = map(lambda x: x/myInt, myList)
>>> newList
[1, 2, 3, 4, 5, 6, 7, 8, 9]
2011/11/23

myList = [10,20,30,40,50,60,70,80,90]
myInt = 10
newList = [i/myInt for i in myList]
2011/11/23

The abstract version can be:

import numpy as np
myList = [10, 20, 30, 40, 50, 60, 70, 80, 90]
myInt = 10
newList  = np.divide(myList, myInt)
2018/10/03

myInt=10
myList=[tmpList/myInt for tmpList in range(10,100,10)]
2018/10/18

Source: https://stackoverflow.com/questions/8244915
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