Is that possible to divide all elements in C# double list to that double list elements sum (which makes total = 1)

Question

Imagine a doube list like the follow

List<double> lstDouble=new List<double>{4,6,2,7,1,1};

So what i want is dividing all elements in this list to sum of the elements(21).

So the list becomes after dividing :

lstDouble = {4/21,6/21,2/21,7/21,1/21,1/21}

Which would mean that the new sum of the elements = 1

I can do that via iteration etc but i wonder are there any short way since Matlab has. And my assistant professor keep telling me that learn Matlab and use it but i don't want :D I love C#

Thank you.

C# 4.0 WPF application

Note that the sum will be approximately 1 afterwards, and not exactly 1. Depending on the values the approximation might be pretty bad. — CodesInChaos, Apr 05 '12 at 00:01
Do you want to modify the input array, or do you want to return a new, modified array? — CodesInChaos, Apr 05 '12 at 00:06
I handled that lstTempDouble = lstTempDouble.Select(x => x / sum).ToList(); — Furkan Gözükara, Apr 05 '12 at 00:07

score 12 · Accepted Answer · answered Apr 04 '12 at 23:59

12

var sum = lstDouble.Sum();
var result = lstDouble.Select(d => d / sum);

answered Apr 04 '12 at 23:59

Tim Schmelter

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score 4 · Answer 2 · answered Apr 04 '12 at 23:59

4

You can do this with LINQ:

var sum = lstDouble.Sum();
var newLst = lstDouble.Select( x => x/sum );

answered Apr 04 '12 at 23:59

Ethan Brown

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score 2 · Answer 3 · answered Apr 04 '12 at 23:58

2

Use a lambda expression:

 lstDouble.ForEach(x => x = x/21);

answered Apr 04 '12 at 23:58

Eugene Feingold

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1

`21` is a variable number that depends on the size and values of the array. – kasavbere Apr 05 '12 at 00:00

score 2 · Answer 4 · answered Apr 05 '12 at 00:00

2

var sum = lstDouble.Sum();
var result = lstDouble.Select(v => v / sum);

answered Apr 05 '12 at 00:00

RobIII

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@CodeInChaos Yeah, thought of that just after I posted. Corrected. Now I have the same answer as everybody else here :-) – RobIII Apr 05 '12 at 00:04

kasavbere · Answer 5 · 2012-04-05T00:06:56.237

0

This is a pseudo code:

double sum = 0;
for(int i=0; i<array.length; i++)
   sum+=array[i];
for(int i=0; i<array.length; i++)
   array[i]=array[i]/sum;

edited Apr 05 '12 at 00:06

answered Apr 04 '12 at 23:59

kasavbere

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down vote is supposed to mean the code would not work. So why the negative vote? – kasavbere Apr 05 '12 at 00:02
even that does not warrant a down vote. The poster could figure it out from there. – kasavbere Apr 05 '12 at 00:06
2

downvote means the answer is "not useful". the question states "I can do that via iteration", which is what this answer is doing, which makes this answer not useful in the context of the question. – Ethan Brown Apr 05 '12 at 00:15

Is that possible to divide all elements in C# double list to that double list elements sum (which makes total = 1)

5 Answers5