MATLAB: Inserting data of one matrix into another

matrixvectors

If I have a vector a

and a vector b

5
6

and I want to input the data of b into the nonzero elements of a (which will always be together and matching the dimensions of b), so that vector c reads

What is an easy way to do this? Thank you!

Another example that it needs to work for:

a    b          c
_    _          _
0    4          0
0    8          0
1    3   ---->  4
1    7          8
1               3 
1               7

Best Answer

a(a ~= 0) = b

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MATLAB: How to delete specific columns from a matrix

Of course, it does not work:

for i = length(matrix):1

I assume you're trying to run the loop in reverse so that you don't shift rows yet to process as you delete rows. That's not how you tell matlab to run a loop in reverse. You have to specify the increment/decrement. Also, never use length on a matrix. If your n is less than 3, it'll return the number of columns instead and leads to interesting bugs. Always use size with an explicit dimension. So:

for i = size(matrix, 2):-1:1

would work. However, a loop is just a waste of time when it can all be accomplished in just one line with:

matrix(:, matrix(1, :) == 0) = [];

MATLAB: How to separate a matrix randomly

Randomly allocate all values from one matrix to two other matrices:

>> A = [0,0,0,0;0,0,0,0;1,1,1,1;1,1,1,1];
>> B = 0.5<rand(size(A));
>> C1 = zeros(size(A)); C2 = zeros(size(A));
>> C1(B) = A(B);
>> C2(~B) = A(~B);

If you only require the last two rows of values, then you can "&" the index with another logical matrix giving the restrictions that you require.

Best Answer

Related Solutions

MATLAB: How to delete specific columns from a matrix

MATLAB: How to separate a matrix randomly

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