loading ggplot2 does not also load required packages plyr and reshape

Question

This problem seems to have started when I updated to R version 2.14.2 and ggplot2 version 0.9.0. When I load the ggplot2 package, it does not also load plyr or reshape , so I can't use, for example melt . I have the packages installed, and required packages are loaded in other cases, it seems like only ggplot2 is affected.

> library(ggplot2)
> cushny$SubjID <- as.factor(LETTERS[1:nrow(cushny)])
> cushny.m <- melt(cushny, id="SubjID", measure=c("Control", "drug1", "drug2L", "drug2R"), variable.name="Condition", value.name="Sleep")
Error: could not find function "melt"
> library(lme4)
Loading required package: Matrix
Loading required package: lattice

Of course I can manually load the required packages, but that seems strange. Has anyone else encountered this problem? Any idea what went wrong?

Answer 1

http://cran.r-project.org/web/packages/ggplot2/NEWS

ggplot2 now uses a NAMESPACE , and only exports functions that should be user visible - this should make it play considerably more nicely with other packages in the R ecosystem. Note that this means you now need to explicitly load plyr (and other packages) if you are using them elsewhere in your code.

Basically, from version 0.9.0, the implementation was changed to avoid possible conflicts when multiple packages were loaded.