add the value of column from text file to the value to matrix
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RUCHI CHOUDHARY
on 14 Sep 2019
Edited: Walter Roberson
on 14 Sep 2019
i create a matrix having userid as a row and itemid as a column ,now i want to add the value of the third column ,in the index value of userid,itemid.Initially fill the matrix by zeros,but now want the value associate with it.
data=load('u.data');
uni_user=unique(data(:,1));
uni_item=unique(data(:,2));
rating_matrix=zeros(length(uni_user(:,1)),length(uni_item(:,1)));
example this is my dataset
196 242 3
186 302 3
22 377 1
196 51 2
now i want a matrix like
5 Comments
Walter Roberson
on 14 Sep 2019
sparse() does not require square matrices.
>> full(sparse(1:5,[1 2 3 1 2],1))
ans =
1 0 0
0 1 0
0 0 1
1 0 0
0 1 0
Accepted Answer
Walter Roberson
on 14 Sep 2019
Edited: Walter Roberson
on 14 Sep 2019
data = load('u.data');
[uni_user, ~, uni_user_idx] = unique(data(:,1));
[uni_item, ~, uni_item_idx] = unique(data(:,2));
rating = data(:,3);
rating_matrix = sparse(uni_user_idx, uni_item_idx, rating);
This will have about 0.6% occupancy and so is well suited for a sparse matrix, but if you have particular reason, you can full() to turn it into a 12 megabyte rectangular array.
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