Às 18:45 de 18/09/2023, mohan radhakrishnan escreveu:
Hello,
I am attempting to port the R code which is an answer to
https://codegolf.stackexchange.com/questions/194229/implement-the-2d-hadamard-transform
function(M){for(i in 1:log2(nrow(M)))T=T%x%matrix(1-2*!3:0,2)/2; print(T);
T%*%M%*%T}
The code, 3 inputs and the corresponding outputs are shown in
https://tio.run/##PYyxCsIwFEX3fkUcAu@VV7WvcSl2dOwi8QNqNSXQJhAqrYjfHoOIwz3D4XBDNOJYiGgerp@td9Diy/gAVlgnynr0A4MLfkkeUTdarnLq5mBXKAvON1W9J8YdZ1rmsk3T72jgV/TAVBHTAROYrs/00@jz5YSY/aOSFKmvGP1yD9sk4Wa7ARSSRowf
These are the inputs.
f(matrix(c(2,3,2,5),2,2,byrow=TRUE))
f(matrix(1,4,4))
f(lower.tri(diag(4),T))
My attempt to port this R code to another framework(Tensorflow) was only
partially successful
because I didn't fully understand the cryptic R code. The second input
shown above works after
hacking Tensorflow for a long time.
My question is this. Can anyone code this in a clear way so that I can
understand ? I understand
Kronecker Product and matrix multiplication and can port that code but I am
missing something as the same ported code does not work for all inputs.
Thanks,
Mohan
[[alternative HTML version deleted]]
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Hello,
Is this what you want?
(I have changed the notation a bit.)
H <- function(M){
H0 <- 1
Transf <- matrix(c(1, 1, 1, -1), 2L)
for(i in 1:log2(nrow(M))) {
H0 <- H0 %x% Transf/2
}
H0 %*% M %*% H0
}
x <- matrix(c(2, 3, 2, 5), 2, 2, byrow = TRUE)
y <- matrix(1, 4, 4)
z <- lower.tri(diag(4), TRUE)
z[] <- apply(z, 2, as.integer)
H(x)
H(y)
H(z)
Hope this helps,
Rui Barradas
______________________________________________
R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
