How to add two columns based on conditions

I was going to try to write a very basic loop (to familiarize myself with writing loops), otherwise not using a loop would probably cost less.

I have a large matrix, but for simplicity, I am trying to add 2 columns together and create the sum in another column in the same matrix.

I want to have two conditions to be met in order for the addition to take place, if conditions are not met, then do not combine values, but still generate the first value.

So I want to add column 3 and 4, if column 1 x<1.5 and if column 2 x==0, then insert into column 5. If the critieria is not met, then copy value from column 3 into 5.

1 0 1 4 5

2 0 1 5 1

1 1.5 2 1 2

if  intrun(:,1)<1.50) & (intrun(:,2)==0;
    intrun(:,5)= intrun(:,3)+intrun(:,4);
end

    

Thank You

Answer 1

[Star Strider]

It is easiest to use 'logical indexing' for this.

Try this --

intrun = [1      0       1    4; 2      0       1    5; 1     1.5    2     1]

intrun = 3×4

1.0000 0 1.0000 4.0000 2.0000 0 1.0000 5.0000 1.0000 1.5000 2.0000 1.0000

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Lv = intrun(:,1)<1.50 & intrun(:,2)==0

Lv = 3×1 logical array
   1
   0
   0

intrun(Lv,5) = intrun(Lv,3) + intrun(Lv,4)

intrun = 3×5

1.0000 0 1.0000 4.0000 5.0000 2.0000 0 1.0000 5.0000 0 1.0000 1.5000 2.0000 1.0000 0

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intrun(~Lv,5) = intrun(~Lv,3)

intrun = 3×5

1.0000 0 1.0000 4.0000 5.0000 2.0000 0 1.0000 5.0000 1.0000 1.0000 1.5000 2.0000 1.0000 2.0000

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.

[Eric]

Thank you!

[Star Strider]

As always, my pleasure!