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The purpose of code on programming

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Shuoze Xu
Shuoze Xu 2022-3-27
评论： Shuoze Xu 2022-3-27
Hi.
I met a few questions when i watch this code
i seen the comment, but i have no idea why the picture produced like that.
i also confuse for the imageData=[imageData; imageRow]; i know the function of ";", but why it used in here?
% make a 2d array of values.
imageData=[]; % set up an empty array
imSize=100;
numRows=imSize;
numCols=imSize;
%populate using a nested loop
for row=[1:numRows]
imageRow=[]; %empty vector for row
for col=[1:numCols]
pixelVal=uint8((row+col)/(imSize*2) * 255); % make a pixel val in 0..255
imageRow=[imageRow pixelVal]; %add value for pixel
end
imageData=[imageData; imageRow]; % add row of pixels
end
% display as an image
imshow(imageData);
% save as an image
imwrite(imageData,'test.png');
% load an image
newImageData=imread('test.png');
% print information about what is stored in the variable
whos newImageData;

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Image Analyst
Image Analyst 2022-3-27
I'm not sure why you said "i know the function of ";", but why it used in here?"
In
imageData=[imageData; imageRow];
the first semicolon says that the rowVector imageRow is to be concatenated below the 3-D matrix imageData.
They're essentially building up the matrix row-by-row by appending the current row to the matrix they're building up.
The second semicolon tells it not to type the whole matrix -- all values of it -- to the command window.
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Image Analyst
Image Analyst 2022-3-27
That's the formula they're using to make the values go from 0 in the upper left to 255 in the lower right.
Shuoze Xu
Shuoze Xu 2022-3-27
I got it.
Thank you for your help.

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