How can I find index from a 3D matrix?

Hi, I have a matrix M that is of this size: M = 376x268x764 double.

Here, 376x268 are latitude longitude grid cells and 764 is the day counts.

Now, from that 764 days, I want to precicely select these 16 days -

d = [1, 3, 45, 56, 111, 121, 135, 440, 489, 491, 511, 555, 569, 599, 608, 700];

in a way that, I still have a 3D matrix but the new size is 376x268x16

Can anyone please help me doing this?

Answer 1

[Matt J]

M=rand(376,268,764);
d = [1, 3, 45, 56, 111, 121, 135, 440, 489, 491, 511, 555, 569, 599, 608, 700];

Md=M(:,:,d);

whos M Md

  Name        Size                     Bytes  Class     Attributes

  M         376x268x764            615894016  double              
  Md        376x268x16              12898304  double              

[Ashfaq Ahmed]

Hi @Matt J, thanks! Yes, that was exactly what I wanted. Can you please tell me how can I average the values for the lat/lon grid for all these 16 arrays so that I have the Averaged_Md of size 376x268x1?

[Ashfaq Ahmed]

Got it, I guess it should be mean(Md,3)