How can I make a column appending columns which are of size of sum of other column?

suppose i have three matrix of same length lat, lon and CG as

lat=[1 2 3 4 5];CG=[5 10 20 11 12];

i want to make like

lat=[lat(1).*ones(CG(1),1);lat(2).*ones(CG(2),1);lat(3).*ones(CG(3),1);lat(4).*ones(CG(4),1);lat(5).*ones(CG(5),1);];

how to do it with loop for large vectors?

i tried like this

n=length(CG)-1;

for i=1:n

kk=lat(i).*ones(CG(i),1);

kk1=[kk;lat(i+1).*ones(CG(i+1),1)]

end

it doesnot work.

Answer 1

[Stephen23]

>> lat = [1,2,3,4,5];
>> CG  = [5,10,20,11,12];
>> V = cell2mat(arrayfun(@(v,n)v*ones(n,1),lat(:),CG(:),'uni',0))
V =
   1
   1
   1
   1
   1
   2
   2
   2
   2
   2
   2
   2
   2
   2
   2
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   3
   4
   4
   4
   4
   4
   4
   4
   4
   4
   4
   4
   5
   5
   5
   5
   5
   5
   5
   5
   5
   5
   5
   5

Or, if you really want to use a loop:

N = numel(lat);
C = cell(N,1);
for k = 1:N
    C{K} = lat(k).*ones(CG(k),1);
end
V = vertcat(C{:})

Answer 2

[TADA]

lat=[1 2 3 4 5];
CG=[5 10 20 11 12];
output = repelem(lat', CG, 1);

[Totanly]

??? Undefined function or method 'repelem' for input arguments of type 'double'.

Answer 3

[Totanly]

lat2=lat(1).*ones(CG(1),1);

for k=2:length(CG)

lat2=[lat2;lat(k).*ones(CG(k),1)];

end

i made like this but its taking long time for large data.

[TADA]

Try Preallocating lat2 For Better Performance

[TADA]

try this:

lat=[1 2 3 4 5];
CG=[5 10 20 11 12];
windowIndices = [0 cumsum(CG)];
lat2=zeros(1,sum(CG));
for k=1:length(CG)
    lat2(windowIndices(k)+1:windowIndices(k+1)) = repmat(lat(k), 1, CG(k));
end

Answer 4

[Andrei Bobrov]

J = cumsum(CG);
ii = zeros(J(end),1);
ii(J-CG+1) = 1;
out = lat(cumsum(ii));