Randomly generate a vector containing integers. Extract items from odd positions using a single command line

Hi guys. How can i randomly generate a vector containing integers and extract items from odd positions using a single command line?

Thank you!

Answer 1

[Konrad]

Hi Dacian,

indexing an expression (e.g. randi(100,10,1)(1:2:9)) is not possible in Matlab.

Here is a workaround using groupsummary() that generates 10 random integers between 1 and 100 and returns the numbers at odd indices:

groupsummary(randi(100,10,1), reshape(repmat(1:2:10,2,1),[],1), @(x)x(1))

ans = 5×1

7 98 61 16 93

You can also put this into an anonymous function (although if creating an anonymous function first is an option, there would be much simpler solutions, of course):

randi_oddIdx = @(imax,n)groupsummary(randi(imax,n,1), reshape(repmat(1:2:n,2,1),[],1), @(x)x(1))

Note that this only works for even numbers of random integers!

Best, Konrad

[Dacian Andrei Firca]

Thank you!

Answer 2

[Walter Roberson]

struct('d',randi(100,1,1)).d(1:2:end)

Does not require that the number of values is even.

Seems pointless to me unless you are carefully controlling the random seed. Just wastes time and is unclear. The numbers are not more random by taking every second one instead of all of them.

[Dacian Andrei Firca]

Thank you!