Determine Which Packages Are Used

Question

Is there a quick way to scan an R script and determine which packages are actually being used? By this I mean looking at all the functions called in the script and returning a list of packages containing these function names? (I know that function names are not exclusive to any one package)

Why not just take a look at packages called library() or require() ? Right. Well, I have a bad habit of downloading packages that I often use, regardless of whether I really use them in the script.

I would like to clear some scripts that I intend to use for others by removing unused packages.

I decided to change my path in 2016. Please help me get started.

Update

Some good ideas in the comments ...

 # create an R file that uses a few functions fileConn<-file("test.R") writeLines(c("df <- data.frame(v1=c(1, 1, 1), v2=c(1, 2, 3))", "\n", "m <- mean(df$v2)", "\n", "describe(df) #psych package"), fileConn) close(fileConn) # getParseData approach pkg <- getParseData(parse("test.R")) pkg <- pkg[pkg$token=="SYMBOL_FUNCTION_CALL",] pkg <- pkg[!duplicated(pkg$text),] pkgname <- pkg$text pkgname # [1] "data.frame" "c" "mean" "describe" 

Update 2

An ugly attempt to implement @nicola's idea:

 # load all probable packages first pkgList <- list(pkgname) for (i in 1:length(pkgname)) { try(print(packageName(environment(get(pkgList[[1]][i]))))) } 

This does not like the c() function, but the results look otherwise correct.

 #[1] "base" #Error in packageName(environment(get(pkgList[[1]][i]))) : # 'env' must be an environment #[1] "base" #[1] "psych" 

Answer 1

Answer based on ideas in the comments to the question. Key functions are getParseData() and packageName() .

 # create an R file that uses a few functions fileConn<-file("test.R") writeLines(c("df <- data.frame(v1=c(1, 1, 1), v2=c(1, 2, 3))", "\n", "m <- mean(df$v2)", "\n", "describe(df) #psych package"), fileConn) close(fileConn) # getParseData approach pkg <- getParseData(parse("test.R")) pkg <- pkg[pkg$token=="SYMBOL_FUNCTION_CALL",] pkg <- pkg[!duplicated(pkg$text),] pkgname <- pkg$text pkgname # [1] "data.frame" "c" "mean" "describe" # load all probable packages first pkgList <- list(pkgname) for (i in 1:length(pkgname)) { try(print(packageName(environment(get(pkgList[[1]][i]))))) } #[1] "base" #Error in packageName(environment(get(pkgList[[1]][i]))) : # 'env' must be an environment #[1] "base" #[1] "psych" 

I will show it correctly, but will gladly consider other solutions.