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Extracting every row from a matrix using a for loop

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Edward Keavney
Edward Keavney 2021-10-15
评论： Rik 2021-10-15
I'm working with some velocity data and have a matrix 23,999x31.
I'm new to using Matlab, I'm able of extracting one row but would now like to be able to create a for loop that will allow me to extract each of the 23,999 rows in the matrix.
Any help for a Matlab novice would be greatly appreciated!

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回答（1 个）

Rik
Rik 2021-10-15
This might not be optimal, depending on what you want to do, but the size function is here to help:
data=rand(23999,31)
for row=1:size(data,1)
rowdata=data(row,:);
%do something with that row here
end
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Edward Keavney
Edward Keavney 2021-10-15
Understood, thanks. I've been approaching the problem in the wrong way. I want to be able to determine the mean from each of the 23,999 rows. Can you help with this?
Rik
Rik 2021-10-15
Ran in:
You can do that with the code I already posted:
data=(1:5).'+rand(5,2);% row x will have values x.####
for row=1:size(data,1)
rowdata=data(row,:);
mean(rowdata) %you can store this in a vector
end
ans = 1.1014
ans = 2.4187
ans = 3.5720
ans = 4.6323
ans = 5.6558
But it is better to use mean on the entire array:
mean(data,2) % specify the dimension to make it operate on the rows
ans = 5×1
1.1014 2.4187 3.5720 4.6323 5.6558

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