extract multiple slices of difference sizes from a vector
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Hi all,
I have a vector A of the shape:
A = [1 4 6 5 4 8 7 8 6 4];
and I want to split this vector into slices. The number of slices is 3 and each slice contains a certain number of elements as follows:
num_groups = 3;
num_points_in_each_group = [2 3 5];
I want the result to be: 
. I have tried with the code below, but it's not working:
. I have tried with the code below, but it's not working:for i = 1:num_groups
end_count = num_points_in_each_group(i);
if i == 1
start_count = 1;
else
start_count = num_points_in_each_group(i-1) + 1;
end
A_slice = A(start_count:end_count);
end
Any help would be appreicted.
Thanks
1 个评论
Here is a simple modification to your code to work as intended to increase your understanding hopefully.
Since you are new, for loops might be tempting since it is easy to understand. However, keep in mind they are not efficient and you should work towards vectorization whereever possible.
A = [1 4 6 5 4 8 7 8 6 4];
num_groups = 3;
num_points_in_each_group = [2 3 5];
for i = 1:num_groups
% your end count is sum of previous group sizes and current group size
end_count = sum(num_points_in_each_group(1:i));
% your start count is 1+numberOfPointsOfPreviousGroup
start_count = 1+sum(num_points_in_each_group(1:(i-1)));
% you need to store it as cell since groups can have different number of elements
A_slice{i} = A(start_count:end_count);
end
A_slice
回答（2 个）
The MATLAB approach:
A = [1 4 6 5 4 8 7 8 6 4];
N = [2 3 5];
C = mat2cell(A,1,N);
Checking:
C{:}
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