Does this constitute a bug, or is there something I'm missing?
assigning sub-elements of a sparse Matrix via M[X]<-..., where X is a
2-column matrix, appears to drop user-assigned attributes. I dug around
in the R code for Matrix trying to find the relevant machinery but my
brain started to hurt too badly ...
Will submit this as a bug if it seems warranted.
library(Matrix)
m1 <- matrix(1:9,3,3)
m1 <- Matrix(m1)
attr(m1,"junk") <- 12
stopifnot(isTRUE(attr(m1,"junk")==12)) ## OK
m1[cbind(1:2,2:3)] <- 1
stopifnot(isTRUE(attr(m1,"junk")==12)) ## not OK
attr(m1,"junk") ## NULL
## note I have to use the ugly stopifnot(isTRUE(...)) because a missing
attribute returns NULL, an assignment to NULL returns NULL, and
stopifnot(NULL) doesn't stop ...
cheers
Ben Bolker
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