I am trying to run the following piece of code. Whenever I try to run the code I get the following error: Error in eval(expr, envir, enclos) : could not find function "."
How can I fix it? Could someone help?
data(mtcars)
library(data.table)
mtcarsDT <- data.table(mtcars)
mtcarsDT[ mpg > 20,
.(AvgHP = mean(hp),
"MinWT(kg)" = min(wt * 453.6)), # wt lbs
by = .(cyl, under5gears = gear < 5)
]
Here is the session info
> sessionInfo()
R version 3.1.2 (2014-10-31)
Platform: x86_64-apple-darwin10.8.0 (64-bit)
locale:
[1] en_US.UTF-8/en_US.UTF-8/en_US.UTF-8/C/en_US.UTF-8/en_US.UTF-8
attached base packages:
[1] stats graphics grDevices utils datasets methods base
other attached packages:
[1] data.table_1.9.2
loaded via a namespace (and not attached):
[1] digest_0.6.8 htmltools_0.2.6 plyr_1.8.1 Rcpp_0.11.3 reshape2_1.4.1 rmarkdown_0.3.3 stringr_0.6.2
[8] tools_3.1.2
Apparently the instructions I offered 2.5 years ago are still current for people using out-of-date versions of Mac R. Assuming you have Xcode and the Command Line Tools installed, you need to first either a) restart R (without loading any of the versions of data.table., reshape2, and dplyr), or b) remove any loaded Namespaces that might conflict with the ability to test-load the new packages:
unloadNamespace('data.table')
unloadNamespace('reshape2')
unloadNamespace('plyr')
Then build from source:
install.packages("data.table", type="source", dependencies=TRUE)
The reason that building from source might work when installing a binary package might not is that the former strategy gets you better checking for version dependencies.
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