## ----setup, echo=FALSE, results='hide', warning=FALSE---------------------------------------------
knitr::opts_chunk$set(
  message = FALSE,
  warning = FALSE,
  background = '#F7F7F7',
  fig.align = 'center',
  dev = 'png',
  comment = "#>"
)

# keep examples from using more than 2 cores
data.table::setDTthreads(Sys.getenv("OMP_THREAD_LIMIT", unset = 2))

options(width = 100, stringsAsFactors = FALSE, timeout = 600)