data.tree YAML function

Readme.rm

This demonstrates how to add functions to a YAML.

functions.R

Remainder <- function(self) {
  1 - sum( Get(self$siblings, "p"))
}

jennylind.yaml

name: Jenny Lind
type: decision
Sign with Movie Company:
  type: chance
  Small Box Office:
    type: terminal
    p: 0.3
    payoff: 200000
  Medium Box Office:
    type: terminal
    p: 0.6
    payoff: 1000000
  Large Box Office:
    type: terminal
    p: "function:Remainder"
    payoff: 3000000
Sign with TV Network:
  type: chance
  Small Box Office:
    type: terminal
    p: 0.3
    payoff: 900000
  Medium Box Office:
    type: terminal
    p: 0.6
    payoff: 900000
  Large Box Office:
    type: terminal
    p: "function:Remainder"
    payoff: 900000

LoadFunctionYaml.R

#requires data.tree 0.2.2
library(data.tree)
library(yaml)
library(stringr)

fileName <- 'jennylind.yaml'
l <- yaml.load_file(fileName)
jl <- as.Node(l)

#this file contains all the functions referred to from the yaml
source("functions.R")

#function to replace the function tags with their actual functions
ReplaceFunction <- function(x) {
  for( field in x$fields) {
    if (str_detect(x[[field]], "function[:][:alpha:]+")) {
      functionName <- str_sub(x[[field]], str_locate(x[[field]], ":")[1, 1] + 1)
      x[[field]] <- eval(parse(text = functionName))
    }
  }
}

#actually do the replacement
jl$Do(ReplaceFunction)

print(jl, "p")