R/monitor_trim.R

In MazamaScience/PWFSLSmoke: Utilities for Working with Air Quality Monitoring Data

#' @keywords ws_monitor
#' @export
#' @title Trim ws_monitor Time Axis to Remove NA Periods From Beginning and End
#' @param ws_monitor \emph{ws_monitor} object
#' @return A \emph{ws_monitor} object with missing data trimmed.
#' @description Trims the time axis of a \emph{ws_monitor} object to exclude timestamps prior to the first and
#' after the last valid datapoint for any monitor.
#' @examples
#' \dontrun{
#' # Fail gracefully if any resources are not available
#' try({
#'
#' library(PWFSLSmoke)
#' library(MazamaSpatialUtils)
#'
#' sm13 <- wrcc_createMonitorObject(20150101, 20151231, unitID = 'sm13')
#' sm13$meta[,c('stateCode','countyName','siteName','monitorID')]
#' Deschutes <- monitor_subset(sm13, monitorIDs='lon_.121.453_lat_43.878_wrcc.sm13')
#' Deschutes <- monitor_trim(Deschutes)
#' monitor_dailyBarplot(Deschutes)
#'
#' }, silent = FALSE)
#' }
monitor_trim <- function(ws_monitor) {

  # Sanity check
  if ( monitor_isEmpty(ws_monitor) ) stop("ws_monitor object contains zero monitors")

  # Vectors of first and last valid indices excluding 'datetime'
  firstValids <- unlist(lapply(ws_monitor$data, function(x) { min(which(!is.na(x))) }))[-1]
  lastValids <- unlist(lapply(ws_monitor$data, function(x) { max(which(!is.na(x))) }))[-1]
  validIndexes <- max(firstValids):min(lastValids)

  # Subset the data dataframe
  ws_monitor$data <- ws_monitor$data[validIndexes,]

  return( structure(ws_monitor, class = c("ws_monitor", "list")) )

}