Multi indexing question on structured array

I have an array

a(1).data=rand(3,1); a(2).data=rand(4,1) ; a(3).data = rand(5,1) ; a(4).data = rand(5,1)

and a vector of the same length as the struct array a

idx = [ 2, 2, 5, 1]

and I would like to basically get

 [ a(1).data(idx(1)), a(2).data(idx(2)), a(3).data(idx(3)), a(4).data(idx(4)) ]

how do I do this in 1 line?

thanks for the help

Answer 1

[Steven Lord]

You just did.

 [ a(1).data(idx(1)), a(2).data(idx(2)), a(3).data(idx(3)), a(4).data(idx(4)) ]

If you're looking for something that generalizes to any struct array and an idx vector of compatible size, the easiest way would be to use a FOR loop. Preallocate your output then loop over 1:numel(idx) and store the result of the indexing operation into the appropriate element of the output. ["FOR loop" is NOT a "dirty word" in MATLAB. When used appropriately, a FOR loop can be a useful tool. When misused, it can be detrimental to your code's performance and/or readability, but so can any tool.]

[Peter Leoni]

I dont like for loops, so always looking to not use them...

I did find a way by building up the expression as a string and then using eval but i am sure there is a faster way

[Stephen23]

Using a for loop is much more preferable to using eval. Don't use slow, buggy and obfuscated code with eval when you can use a simple, fast and reliable for loop (and some array preallocation).