Interpreting a Zeros function

Hi guys,

I've just received a code and I just can't figure out what this means

idxSampling = zeros(20,1);
    idxSampling(1) = 1;
    for ii = 1:19
        [~,tmp] = min(abs(t-ii));
        idxSampling(ii+1) = tmp;
    end

I'd be much obliged if someone could tell me what the 'idxSampling' function is trying to achieve

Many thanks in advance!

Answer 1

[Walter Roberson]

idxSampling is not a function there: it is an array.

The code assumes that t is a vector of values. The code is finding the indices into the vector that are closest to 1, 2, 3, 4, 5, and so on up to 19.

t = sort(rand(1,15) * 23 - 1)    %some data to use

t = 1×15

0.1225 0.5973 0.7782 4.6402 4.8298 7.9562 10.2478 10.8977 10.9531 12.4351 12.6642 13.4387 17.7164 18.2540 19.4799

In the case that t is all ascending or all descending, another way of writing the code would be

%your existing code
idxSampling = zeros(20,1);
    idxSampling(1) = 1;
    for ii = 1:19
        [~,tmp] = min(abs(t-ii));
        idxSampling(ii+1) = tmp;
    end
idxSampling.'

ans = 1×20

1 3 3 4 4 5 5 6 6 6 7 9 10 11 12 12 13 13 14 15

idxSampling1 = [1, interp1(t,1:length(t), 1:19, 'nearest', 'extrap')]

idxSampling1 = 1×20

1 3 3 4 4 5 5 6 6 6 7 9 10 11 12 12 13 13 14 15

Another way would be

[~, tmp] = min(abs(t(:) - (1:19)),[],1);
idxSampling2 = [1, tmp]

idxSampling2 = 1×20

1 3 3 4 4 5 5 6 6 6 7 9 10 11 12 12 13 13 14 15

(The interp1 version unexpectedly also works if t is not sorted; it could be the case that unsorted is permited for 'nearest' but not generally.)

[frozentangled]

Thanks! Much obliged!

Have a nice day I hope!