problem with nested loop
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Hi, I am trying to write a code with nested for loop and if statement. I want to create a matrix in such way that, for one value of y, I have different values of x and z, and again for another value of y, I have same values for x but different values of z.
load a.dat;
x=a(:,1);
y=a(:,2); z=a(:,3); for j=min(y):1:max(y)
for i=1:10
if j=10
A(:,i)=z(i)
else if
j=j+1
end
end
end
I am not able to apply if statement for y.
Could anyone please help me?
4 commentaires
Stephen23
le 30 Avr 2015
If you upload your actual data matrix then we can try this too! Please upload the data (in a textfile or .mat file) using the paperclip button that you will find above the textbox, and note that you will need to push both buttons: Choose file and Attach file.
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Stephen23
le 30 Avr 2015
Modifié(e) : Stephen23
le 4 Mai 2015
You have x and y values, and it seems that you want to use these as indices for allocating data values into another matrix. This can be achieved very easily using sub2ind. Here is a simple demo-matrix where the first column contains row indices, the second is column contains column indices, and the third contains the data:
>> A = [2,1,5;1,3,7;2,3,0;1,1,9;2,2,4]
A =
2 1 5
1 3 7
2 3 0
1 1 9
2 2 4
% row col data
then we extract the row and column indices:
>> R = A(:,1);
>> C = A(:,2);
create the output matrix and use sub2ind to get the linear indices for those row/column indices:
>> Z = nan(max(R),max(C));
>> X = sub2ind(size(Z), R, C);
and finally use the linear indices to put the data values into their right locations:
>> Z(X) = A(:,3)
Z =
9 NaN 7
5 4 0
Note that MATLAB has one-based indexing, so you will need to add one to the values that you have in your example data.
Plus de réponses (1)
Søren Jensen
le 30 Avr 2015
A(:,i)= z(i)
do you mean A(:,i)= z(:,i) or A(:,i)= z(i,:)?
When is A defined?
i see 2 for statements and 1 if statement, and only 2 "end", so some of your code seems to be missing.. what is the purpose of the code?
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