MATLAB: Difference between values and indices

matrices indices index values

Can someone give an explanation of the difference between the values of elements in a matrix vs. the indices of elements in a matrix?

Thanks.

Best Answer

E.g.

 A = [1 2; 3 4]

Values of/in A are 1,2,3,4. To access the 2 you would use

 val = A(1,2)

(1,2) are the indices of the element of A whose value is 2.

Related Solutions

MATLAB: How to get subset indices

Use the ismember (or ismembertol for floating-point numbers):

M = [1 2 3 6 7 8];
x = [3 7 8];
[~,indices] = ismember(x,M);
Out = M(indices)
Out =
     3     7     8

MATLAB: Merging two arrays based on index arrays

z_index = [2,3];
y_index = [4,1,5];
z(z_index) = [1,3];
y(y_index) = [-2,4,2];
x(z_index) = z(z_index); % RHS = [1,3]
x(y_index) = y(y_index)  % RHS = [-2,4,2]
x = 1×5
     4     1     3    -2     2
●

Or slightly more robustly:

x = [z(z_index),y(y_index)]; % RHS = [1,3,-2,4,2]
x([z_index,y_index]) = x
x = 1×5
     4     1     3    -2     2
●

Best Answer

Related Solutions

MATLAB: How to get subset indices

MATLAB: Merging two arrays based on index arrays

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