digraph "activity" {

node [style = "filled"]

node [shape = "note" fillcolor="white"]

"report.rmd"
"/usr/share/dict/words"

node [shape = "note" fillcolor="lightgray"]

"words.tsv"
"histogram.tsv"

node [shape = "note" fillcolor="lightblue"]

"histogram.png"
"report.html"

"/usr/share/dict/words" -> "words.tsv" [label="cp or RCurl::getURL"]
"words.tsv" -> "histogram.tsv" [label="Rscript"]
"histogram.tsv" -> "histogram.png" [label="ggplot2"]
"histogram.png" -> "report.html"
"report.rmd" -> "report.html" [label="rmarkdown::render"]
}