How to open gaps after uses the "find" command?

I am working with a matrix data=[time depth density], and I am trying to select the densities of a specific range of depth. I tried the following expression:

>>dens=data(:,3);
>>ind_10=find(data(:,2)>=10);
>>dens_10=dens(ind_10);

It worked, but the matrix now have a size smaller than the previous one. I would like to keep dens_10 following the same "time", in order to plot then together. In other words, how can I open gaps on the new matrix in other to this one have the same size as the old one?

Thank you very much!

Answer 1

[Stephen23]

Although find is very attractive for beginners, it is actually faster and neater to use logical indexing, so the equivalent to your code above would be:

ind_10 = data(:,2) >= 10;
dens_10 =  data(ind_10,3);

This also allows us to easily define not only which elements we select from an array, but also those that we allocate into an array:

ind_10 = data(:,2) >= 10;
dens_10(ind_10) = data(ind_10,3);

You will probably need to consider what values to put in the non-allocated positions, something like this:

dens_10(~ind_10) = NaN; % or 0?

[Gustavo Oliveira]

 Works perfectly! Tks Stephen!