how to normalize a uniformly distributed random values such that every row sum of X(:,:,i) should be 1 except for ith row?

how to normalize a uniformly distributed random values such that every row sum of X(:,:,i) should be 1 except for ith row? 'i' value can be anything according to user's choice.

X = rand([n,key_size,6]); where n=6,key_size=3

Here 6 matrices created. Here i want row 5 not to be normalized in all the 6 matrices and keep the original value and all the other row sum of this 6 matrices be normalized? could somone help me in solving this problem. I would be very grateful. thank you

Answer 1

[Chunru]

n=6; key_size=3; i=5;
X = rand([n,key_size,6]); 
idx = [1:i-1 i+1:n];
X (idx, :, :) = X (idx, :, :)./sum(X (idx, :, :), 2);
X

X = 
X(:,:,1) =

    0.1963    0.2355    0.5682
    0.4084    0.3829    0.2087
    0.4225    0.2156    0.3619
    0.6109    0.1880    0.2010
    0.3553    0.0219    0.1098
    0.0393    0.7273    0.2334


X(:,:,2) =

    0.4083    0.3940    0.1977
    0.3497    0.2938    0.3565
    0.4196    0.5791    0.0013
    0.6651    0.1788    0.1561
    0.7057    0.9660    0.4752
    0.3116    0.1548    0.5336


X(:,:,3) =

    0.1459    0.7574    0.0967
    0.3566    0.5568    0.0866
    0.3424    0.3153    0.3423
    0.0998    0.5528    0.3474
    0.4512    0.6269    0.0229
    0.1695    0.4982    0.3323


X(:,:,4) =

    0.1744    0.2141    0.6114
    0.4465    0.4234    0.1301
    0.1581    0.2629    0.5790
    0.4688    0.5284    0.0028
    0.7126    0.7236    0.9397
    0.2849    0.2578    0.4573


X(:,:,5) =

    0.0353    0.2395    0.7252
    0.3029    0.3668    0.3302
    0.6438    0.2772    0.0790
    0.5217    0.3985    0.0798
    0.6972    0.2128    0.6599
    0.2101    0.2926    0.4973


X(:,:,6) =

    0.3236    0.3221    0.3543
    0.5614    0.0772    0.3614
    0.4919    0.5050    0.0031
    0.1608    0.3910    0.4482
    0.3994    0.9686    0.3631
    0.3526    0.1925    0.4549

sum(X, 2)

ans = 
ans(:,:,1) =

    1.0000
    1.0000
    1.0000
    1.0000
    0.4870
    1.0000


ans(:,:,2) =

    1.0000
    1.0000
    1.0000
    1.0000
    2.1470
    1.0000


ans(:,:,3) =

    1.0000
    1.0000
    1.0000
    1.0000
    1.1010
    1.0000


ans(:,:,4) =

    1.0000
    1.0000
    1.0000
    1.0000
    2.3759
    1.0000


ans(:,:,5) =

    1.0000
    1.0000
    1.0000
    1.0000
    1.5698
    1.0000


ans(:,:,6) =

    1.0000
    1.0000
    1.0000
    1.0000
    1.7310
    1.0000