Finding out which functions are called within a given function [duplicate]

by

try this example:

library(codetools)

ff <- function(f) {
  leaf <- function (e, w) {
    r <- try(eval(e), silent = TRUE)
    if(!is.null(r) && is.function(r)) ret <<- c(ret, as.character(e))
  }
  call <- function (e, w) {
    walkCode(e[[1]], w)
    for (a in as.list(e[-1])) if (!missing(a)) walkCode(a, w)
  }
  ret <- c()
  walkCode(body(f), makeCodeWalker(call = call, leaf = leaf, write = cat))
  unique(ret)
}

then,

> ff(data.frame)
 [1] "{"               "<-"              "if"              "&&"              "is.null"         "row.names"       "function"        "is.character"   
 [9] "new"             "as.character"    "anyDuplicated"   "return"          "||"              "all"             "=="              "stop"           
[17] "gettextf"        "warning"         "paste"           "which"           "duplicated"      "["               "as.list"         "substitute"     
[25] "list"            "-"               "missing"         "length"          "<"               "!"               "is.object"       "is.integer"     
[33] "any"             "is.na"           "unique"          "integer"         "structure"       "character"       "names"           "!="             
[41] "nzchar"          "for"             "seq_len"         "[["              "is.list"         "as.data.frame"   ".row_names_info" ">"              
[49] "deparse"         "substr"          "nchar"           "attr"            "abs"             "max"             "("               "%%"             
[57] "unclass"         "seq_along"       "is.vector"       "is.factor"       "rep"             "class"           "inherits"        "break"          
[65] "next"            "unlist"          "make.names"      "match"           ".set_row_names" 
> ff(read.table)
 [1] "{"              "if"             "&&"             "missing"        "file"           "!"              "text"           "<-"             "textConnection"
[10] "on.exit"        "close"          "is.character"   "nzchar"         "inherits"       "stop"           "isOpen"         "open"           ">"             
[19] "readLines"      "<"              "min"            "("              "+"              "lines"          ".Internal"      "quote"          "length"        
[28] "all"            "=="             "pushBack"       "c"              "stdin"          "scan"           "col"            "numeric"        "-"             
[37] "for"            "seq_along"      "["              "max"            "!="             "warning"        "paste0"         ":"              "make.names"    
[46] "names"          "is.null"        "rep"            "match"          "any"            "<="             "rep.int"        "list"           "%in%"          
[55] "sapply"         "do.call"        "data"           "flush"          "[["             "which"          "is.logical"     "is.numeric"     "|"             
[64] "gettextf"       "&"              "is.na"          "type.convert"   "character"      "as.factor"      "as.Date"        "as.POSIXct"     "::"            
[73] "methods"        "as"             "row.names"      ".set_row_names" "as.integer"     "||"             "is.object"      "is.integer"     "as.character"  
[82] "anyDuplicated"  "class"          "attr"

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