Result producing 1x5 array instead of 10x5?

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Thomas Veith
Thomas Veith 2019-6-4
评论： Alex Mcaulley 2019-6-4
Hi all,
I have the following code which I'm expecting to produce a 10x5 array but it's only giving me a 1x5, and I'm not sure why?
n = 10;
result = zeros(n,5);
for k=1:n;
A0=1;P0=29;g=rand;p=rand;B=rand;
result = [A0,P0,g,p,B];
end;
Alternatively, if I write the code this way I get a 10x1 cellular array, each entry of which represents a 1x5 numeric array. This gives me the number of results I want, but not in the format I'm looking for (which, again, is ultimately a 10x5 array). Thanks in advance!
n = 10;
result = cell(n,1);
for k=1:n;
A0=1;P0=29;g=rand;p=rand;B=rand;
result{k} = {A0,P0,g,p,B};
end;

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采纳的回答

Alex Mcaulley
Alex Mcaulley 2019-6-4
You need to specify the index:
n = 10;
result = zeros(n,5);
for k=1:n;
A0=1;P0=29;g=rand;p=rand;B=rand;
result(k,:) = [A0,P0,g,p,B];
end;
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显示 2更早的评论
madhan ravi
madhan ravi 2019-6-4

That would just copy the same g p B values through repmat() so creating n elements for g p B and then copying it into the matrix would be better.

Alex Mcaulley
Alex Mcaulley 2019-6-4
Yes, as @madhan said, if you want random numbers for all rows:
n = 10;
A0=1;P0=29;
result = [repmat([A0,P0],n,1),rand(n,3)]

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更多回答（1 个）

Rob L
Rob L 2019-6-4
Your first method overwites the result every loop with a [ 1 x 5 ] array.
You could (among many other solutions) use:
n = 10;
result = zeros(n,5);
for k=1:n
A0=1;P0=29;g=rand;p=rand;B=rand;
result(k,1) = A0;
result(k,2) = P0;
result(k,3) = g;
result(k,4) = p;
result(k,5) = B;
end

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