Question

Hi I get the error stated below, im trying to normalize between 0 and 1. The error I get is this:

columns =

     6

    ??? Error using ==> minus
    Matrix dimensions must agree.

    Error in ==> Kmeans at 54
        data = ((data-minData)./(maxData));

Not sure what ive did wrong? Full code below:

%% dimensionality reduction 
    columns = 6
    [U,S,V]=svds(fulldata,columns);

%% randomly select dataset
rows = 1000;
columns = 6;

%# pick random rows
indX = randperm( size(fulldata,1) );
indX = indX(1:rows);

%# pick random columns
indY = randperm( size(fulldata,2) );
indY = indY(1:columns);

%# filter data
data = U(indX,indY);

%% apply normalization method to every cell
maxData = max(data);
minData = min(data);
data = ((data-minData)./(maxData));

The dataset is 1000×6.

Answer 1

From the Matlab documentation on min:

If A is a matrix, min(A) treats the columns of A as vectors, returning a row vector containing the minimum element from each column.

If you want to find the global minimum of a matrix, use either of the following forms:

min(min(A))
min(A(:))