Apply the same function into several columns
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Hi!
I have a matrix A (50x50), and every column of the 50 are different subjects. I want to apply the same function to each column separetely and save the answers of the function into a different matrix B(50x1) The function is exactly the same, all that changes is the data on which the function is performed on.
How can I do it?
Thanks!
采纳的回答
Use a loop:
B = zeros(1, size(A, 2));
for column = 1 : size(A, 2)
B(column) = yourfunction(A(:, column));
end
Or you can use cellfun, which is just a loop in disguise:
B = cellfun(@yourfunction, num2cell(A, 1));
edit: That's assuming the function cannot already operate on the columns of the whole matrix, as pointed out by Star.
2 个评论
Jos (10584)
2019-4-4
I suggest the use of arrayfun, rather than cellfun, assuming yourfunction(V) returns a scalar value for a vector V:
B = arrayfun(@(k) yourfunction(A(:,k)) , 1:size(A, 2))
Guillaume
2019-4-4
I find the cellfun more readable personally. Ultimately, you have the cost of an anonymous function call vs the cost of splitting the matrix into a cell array.
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