Multiply a list with a matrix in R

Question

A is a list of 8 matrices dimension 2x2, so length of A=8. How can I multiply each matrix in A with a matrix B dimension 2x2 to get a new list of 8 matrices dim2x2? A and B are already defined.

I know "lapply" may help, but I'm still stuck. Thanks for your help!

Please provide a [reproducible example](http://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example). — David Heckmann, May 10 '17 at 19:47
@DavidHeckmann you mean the exact matrices I have or the code i failed to write properly? — cherrykate, May 10 '17 at 19:52
preferably both, but code to produce the matrices would be a good start. — David Heckmann, May 10 '17 at 20:12
`lapply(list_of_matrices, function(M) {M %*% B})`? You can always amend your question using the "edit" link. — tiwo, May 10 '17 at 21:14

score 4 · Accepted Answer · answered May 10 '17 at 19:52

4

A = list(a = matrix(1:4, 2), b = matrix(2:5, 2))
B = matrix(3:6, 2)
lapply(A, FUN = function(x) x %*% B)

I guess this is what you need, next time please provide a reproducible example.

answered May 10 '17 at 19:52

Sean Lin

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Multiply a list with a matrix in R

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