How to assign value in an array depending on the index stated in another array

Hi

I have an array of size 11x2 where the first column is the index value and the second is the value. I would like to create another array of size 24x1 where the values of the indexs mentioned in the first array are one I tried the following but it did not owrk :

schedule= (zeros(size(24)))

schedule(lowestpricesgrid(:,1))=1

The lowest prices grid contains the following values:

index value

6 39

7 40

5 40

4 40

8 41

3 42

2 44

14 44

9 44

10 45

13 45

The code above returns a array of size 1x14 : 0 1 1 1 1 1 1 1 1 1 0 0 1 1

I would like it to ideally be : 0 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0 0 0 0 0 0 0 0 0

Thank you for the help!

Answer 1

[DGM]

The first problem is this:

zeros(size(24)) % this is a scalar

ans = 0

because

size(24)

ans = 1×2

1 1

As a result, the output vector starts out undersize and is only expanded to accomodate the largest index in the list (14).

Allocating it to the correct size will give a full 24 element vector.

lowestpricesgrid = [6 39;
                    7 40;
                    5 40;
                    4 40;
                    8 41;
                    3 42;
                    2 44;
                    14 44;
                    9 44;
                    10 45;
                    13 45];

schedule = zeros(1,24);
schedule(lowestpricesgrid(:,1)) = 1

schedule = 1×24

0 1 1 1 1 1 1 1 1 1 0 0 1 1 0 0 0 0 0 0 0 0 0 0

[Ritika Srinivasan]

Thank you so much!