How do I extract non sequential rows of a matrix without using a for loop?

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Ryan Melvin 2013-10-2

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https://ww2.mathworks.cn/matlabcentral/answers/88959-how-do-i-extract-non-sequential-rows-of-a-matrix-without-using-a-for-loop

评论： Ryan Melvin 2013-10-2

I have a very large matrix (m1), and I want to create a new matrix (m2) using certain rows of m1. The list of rows I want is contained in a 1xN matrix called "list". Naively, I would expect the command to be

m2 = [m1(list,:)]

However, matlab will not accept a matrix as an index. (I receive the error "Subscript indices must either be real positive integers or logicals.")

Any help would be appreciated.

For context: The matrix m1 is too large for me to attempt this exercise by hand -- it contains 100000 rows. Also, there is no obvious mathematical relationship among the entries in "list".

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Ryan Melvin 2013-10-2

List contains only integers from 0 to 99990.

Ryan Melvin 2013-10-2

Actually, you were correct. List was an output from a program that starts counting from 0; whereas, matlab's indices count from 1. I added 1 to every member of list, and now things work as expected. Thank you.

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