Hi Vince,
This issue was reported here a couple of weeks ago:
https://github.com/Bioconductor/GenomicRanges/issues/11
Internally $<- uses something like:
do.call(DataFrame, list(DF1, DF2))
to combine the metadata columns. However in some situations
the do.call(DataFrame, list(...)) form i
The following comes up in use of Fdb.InfiniumMethylation.hg19::getPlatform
debug: mcols(GR)$channel <- Rle(as.factor(mcols(GR)$channel450))
Browse[3]> system.time(uu <- Rle(as.factor(mcols(GR)$channel450)))
user system elapsed
0.020 0.003 0.022
Browse[3]> system.time(mcols(GR)$chann