How can I convert 1D array into 2D array
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Shafali
el 23 de Feb. de 2017
Comentada: Sebastian Joseph
el 6 de Mayo de 2021
Hello All, This is my sample code:
img=imread('C:\Users\nitin\Documents\MATLAB\t8.png');
img=rgb2gray(img);
[i,j]=size(img);
[x,y]=find(img);
for p=1:i*i
x1(p)=mod(32+(19*p),i);
end
for q=1:j*j
y1(q)=mod(16+(13*q),j);
end
x1=x1';
y1=y1';
After executing the above piece of code, I got x1(64*1) 1D array and y1(64*1) 1D array as new coordinates. Now I want to convert x1 and y1 into (8*8) matrix with new coordinates i.e. (x1,y1). Please help.
3 comentarios
Rik
el 23 de Feb. de 2017
What is it you want to do? x and y both contain 64 values, so you can convert both into 8x8 matrices. So how do you want to combine these two into one?
For changing the shape of a vector/matrix you can use the function reshape
Respuesta aceptada
Guillaume
el 24 de Feb. de 2017
There are a few things that are not quite right with what you're doing
1) you're using x and y as row, column respectively. Standard convention is that x is the horizontal coordinate (column) and y is the vertical coordinate (row).
2) the x1 and y1 you calculate go from 0 to height or width minus 1. matlab indexing starts at 1, not 0. You need to add 1 to your coordinates.
Anyway, you wouldn't need reshape if you'd kept your x, y, x1, and y1 the same shape as the image. An added bonus is that you wouldn't even need the loop:
[y, x] = ndgrid(1:size(img, 1), 1:size(img, 2)); %order is [y, x] or [row, column]
x1 = mod(32 + 19*x, size(img, 2));
y1 = mod(16 + 13*y, size(img, 1));
scrambledimage = img(sub2ind(size(img), y1+1, x1+1));
4 comentarios
Más respuestas (1)
Jan
el 23 de Feb. de 2017
[i,j] = size(img);
x1 = mod(32 + 19* (1:i*i), i);
x1 = reshape(x1, 8, 8);
y1 = mod(16 + 13* (1:j*j), j);
y1 = reshape(y1, 8, 8);
The detail "i.e. (x1,y1)" is not clear to me.
4 comentarios
Jan
el 26 de Feb. de 2017
Exactly, my answer does not work. I've posted it with the intention to clarify the question. See my:
The detail "i.e. (x1,y1)" is not clear to me.
I'm still not sure, what you, Shafali, are asking for, and hope, that Guillaume's answer helps you. If so, please accept his answer, or try to explain the problem with a small example of the input and the wanted result.
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