Help with logical indexing

Hi All,

i have a question about logical indexing.

I have an array of three columns called pressure. Firstly, i check for values < 1000 (low = pressure < 1000) and then i would like to give those values new RGB values [0.1, 0.5, 0.9] so i can create a RGB pressure map.

i tried pressure(low) = [0.1, 0.5, 0.9] but this obviously didnt work. pressure(low) = 0.9 is working but is not the prefered outcome.

Any idead how this might work? Or do i have apply every column seperately like this: pressure(low, 1) = 0.1, pressure(low, 2) = 0.5 ... and so on?

Regards,

Barry

[KALYAN ACHARJYA]

"values < 1000 (low = pressure < 1000)"

Please carify?

• For for individual coloums or all columns have to satisfy
• How does you get thease R,G,B values 0.1, 0.5, 0.9

If you want help, then you need to make it easy to be helped.

:)

Answer 1

[Rishabh Mishra]

Hi,

You can use cell arrays (instead of double arrays) along with loop operations to work out the issue. Use the code below for the purpose,

% Pressure Matrix 
pressure = [1101 450 987;1213 145 1997;148 1533 1420]; 
low = pressure < 1000; 
RGB = {0.1 0.5 0.9}; 
% Convert Matrix to 2D Cell Array 
pressure = num2cell(pressure); 
  
% Replace Pressure values < 1000 by RGB cell 
for k = 1:size(low,1) 
    for j = 1:size(low,2) 
        if low(k,j) 
            pressure{k,j} = RGB; 
        end 
    end 
end 

Hope this helps.