CODEWITHSUNDEEP
matlabmatrix
Taufik Ismail
Taufik Ismail

Reputation: 3

Replacing elements on matrix with row/column by row/column

I have 6 stations and 3 from it are unstable. The unstable stations uspt are, say 2, 3, 6.

Each station represents two columns and two rows e.g station 1 correspond to the rows 1 and 2, station 2 corresponds to the rows 3 and 4 and so on. First two columns correspond to the first unstable station which is station 2. Next two columns (columns 3 and 4) correspond to the next unstable station which is station 3 and so on.

I want to create a matrix B which assigns number 1 for unstable points using the above information and zeros to all other points. So for the given number of total stations and unstable of them, following is the desired output:

B = [0   0   0   0   0   0
     0   0   0   0   0   0
     1   0   0   0   0   0
     0   1   0   0   0   0
     0   0   1   0   0   0
     0   0   0   1   0   0
     0   0   0   0   0   0
     0   0   0   0   0   0
     0   0   0   0   0   0
     0   0   0   0   0   0
     0   0   0   0   1   0
     0   0   0   0   0   1]

Here is what I have tried:

%my input
stn=6;                  %no of stations
us=3;                   %no of unstable stations
uspt=[2 3 6]            %unstable station

m=stn*2;                %size of matrix, no of row
u=(stn)-us;             %no of stable station
n=m-2*u;                %no of column

B = zeros(m,n);
io=uspt(2:2:length(uspt));ie=uspt(1:2:length(uspt));       %ie=even numb/io=odd numb
for ii=numel(B+1,2)
    if ie>0|io>0
        ii=ii+1;
        B(ie*2-1,ii-1)=1;B(ie*2,ii)=1;
        ii=ii+1;
        B(io*2-1,ii)=1;B(io*2,ii+1)=1;
    end
end
B=B

And what I got:

B = [0   0   0   0   0   0
     0   0   0   0   0   0
     1   0   0   0   0   0
     0   1   0   0   0   0
     0   0   1   0   0   0
     0   0   0   1   0   0
     0   0   0   0   0   0
     0   0   0   0   0   0
     0   0   0   0   0   0
     0   0   0   0   0   0
     1   0   0   0   0   0
     0   1   0   0   0   0]

I got the correct assignment for the 2 and 3 stations while wrong assignment position for 6 station. How can I achieved the correct assignment for 6 station or any station?

Upvotes: 0

Views: 71

Answers (1)

Sardar Usama
Sardar Usama

Reputation: 19689

You don't need a loop here. 

m = stn*2;         %Number of rows of the required matrix
n = numel(uspt)*2; %Number of columns of the required matrix
B = zeros(m,n);    %Initializing B with all zeros

%finding row and column indices whose elements are to be changed
row = sort([uspt*2-1, uspt*2]);   %sorted row indices
col = 1:n;         %column indices

linInd = sub2ind([m,n], row,col); %Converting row and column subscripts to linear indices
B(linInd) = 1;     %Changing the values at these indices to 1

Or as a two liner:

B = zeros(stn*2, numel(uspt)*2);
B(sub2ind([stn*2,numel(uspt)*2], sort([uspt*2-1, uspt*2]),1:numel(uspt)*2) = 1;

Upvotes: 1

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