adding elements to beginning of each row
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I have a 3x4 array that looks like this [1,2,3,4; 5,6,7,8; 9,10,11,12]. I want to add n number of zeros (n being the row number), so that it looks like this [0,1,2,3,4,0,0; 0,0,1,2,3,4,0; 0,0,0,1,2,3,4] Is there any way to achieve this in Matlab? rows and arrays work quite differently from my programming knowledge so I'm having a little difficulty.
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Image Analyst
2018-3-10
So
m1 = [1,2,3,4; 5,6,7,8; 9,10,11,12] % Input
m2 = [0,1,2,3,4,0,0; 0,0,1,2,3,4,0; 0,0,0,1,2,3,4] % Desired output
gives
m1 =
1 2 3 4
5 6 7 8
9 10 11 12
m2 =
0 1 2 3 4 0 0
0 0 1 2 3 4 0
0 0 0 1 2 3 4
What rule are you giving for transferring some (but not all) of the elements from m1 to m2?
Have you considered circshift()?
采纳的回答
Akira Agata
2018-3-10
I think the desired result could be the following.
0 1 2 3 4 0 0
0 0 5 6 7 8 0
0 0 0 9 10 11 12
Assuming this, the solution would be like this.
A = [1,2,3,4; 5,6,7,8; 9,10,11,12];
A1 = [A,zeros(3)];
B = splitapply(@(x,d) circshift(x,d), A1, (1:3)', (1:3)');
更多回答（1 个）
Image Analyst
2018-3-10
Here's one way:
m1 = [1,2,3,4; 5,6,7,8; 9,10,11,12]
% m2 = [0,1,2,3,4,0,0; 0,0,1,2,3,4,0; 0,0,0,1,2,3,4]
rowOne = [0, m1(1,:), zeros(1, size(m1, 2)-2)]
m2 = repmat(rowOne, [size(m1, 1), 1])
for row = 1 : size(m2, 1)
thisRow = m2(row, :)
m2(row,:) = circshift(thisRow, row-1);
end
m2 % Show in command window.
It gives
m2 =
0 1 2 3 4 0 0
0 0 1 2 3 4 0
0 0 0 1 2 3 4
just like you requested.
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