How do I use an matrix of indices to reference values in another matrix without using a loop?

I have a matrix that contains 20 vertical temperature values. It is of size 20 X 751 X 1500. Call this matrix alltemps.

I have another matrix that contains an index into the first dimension of the temperature. It is of size 1 X 751 X 1500. Call this matrix tempindex.

I want to create another 1 X 751 X 1500 matrix that is the temperature value from alltemps at the index pointed to by tempindex for all 751 X 1500 point in alltemps. Call this new matrix savedtemp

For example at 200 X 200, the temperature values in alltemps are:

280 282 284 286 288 290 292 294 296 298 300 302 304 306 308 310 312 314 316 318

And at 200 X 200, the (index) value in tempindex is 3.

So, the value in savedtemp would be 284 at 200 X 200 (i.e. the 3rd value in the temperature dimension of alltemps at 200 X 200.)

Is there a way to make a blanket (matrix-wise) assignment for every point in in the 751 X 1500 vector like this without having to run a loop?

Answer 1

[Roger Stafford]

[a,b,c] = size(alltemps);  % tempindex must be 1 x b x c
savedtemp = reshape(alltemps(reshape(tempindex,1,[])+(0:a:a*(b*c-1))),1,b,c);

[Joseph Koval]

Thanks Roger. Works like a charm!