matrix-indexing

I have a cell array A [1x80] in which each element is a cell array itself [9x2]. I have also a vector B representing a group of selected cells of A and I want to extract the element {2,2} of each selected cell. I tried with a simple A(1,B){2,2} but of course it doesn't work.... Can you help me? How about this: A = {{1 2; 3 4}, {5 6;7 8}, {9 0; 1 2}; {3 4; 5 6}, {7 8; 9 0}, {11 22; 33 44}}; B = [2,3] [cellfun(@(x)x(2,2), A){1, B}] ans = 8 2 EDIT: The above actually only works in octave. As @Amro points out, to modify it to work in Matlab you need to use a temporary variable: temp = cellfun(@(x

I have a 3d numpy array ( n_samples x num_components x 2 ) in the example below n_samples = 5 and num_components = 7. I have another array ( indices ) which is the selected component for each sample which is of shape ( n_samples ,). I want to select from the data array given the indices so that the resulting array is n_samples x 2 . The code is below: import numpy as np np.random.seed(77) data=np.random.randint(low=0, high=10, size=(5, 7, 2)) indices = np.array([0, 1, 6, 4, 5]) #how can I select indices from the data array? For example for data 0, the selected component should be the 0th and

I have a matrix that has a quite sparse index (the largest values in both rows and columns are beyond 130000), but only a few of those rows/columns actually have non-zero values. Thus, I want to have the row and column indices shifted to only represent the non-zero ones, by the first N natural numbers. Visually, I want a example matrix like this 1 0 1 0 0 0 0 0 1 to look like this 1 1 0 1 but only if all values in the row/column are zero. Since I do have the matrix in a sparse format, I could simply create a dictionary, store every value by an increasing counter (for row and matrix separately)

This issue appeared when I was answering this question . It should be some stupid error I am doing, but I can't get what error it is… myMatrix = [22 33; 44 55] Returns: >> subsref(myMatrix, struct('type','()','subs',{{[1 2]}} ) ); ans = 22 44 While using it with cells: myCell = {2 3; 4 5} Returns: >> subsref(myCell,struct('type','{}','subs',{{[1 2]}} ) ); ans = 2 % WHATTT?? Shouldn't this be 2 and 4 Matlab?? Checking the subsref documentation , we see: See how MATLAB calls subsref for the expression: A{1:2} The syntax A{1:2} calls B = subsref(A,S) where S.type='{}' and S.subs={[1 2]}. This