R/getLevel2BPAIProfile.R

In rGEDI: NASA's Global Ecosystem Dynamics Investigation (GEDI) Data Visualization and Processing

#'Get GEDI Plant Area Index (PAI) Profile (GEDI Level2B)
#'
#'@description This function extracts the Plant Area Index (PAI) Profile from GEDI Level2B data.
#'
#'@usage getLevel2BPAIProfile(level2b)
#'
#'@param level2b A GEDI Level2B object (output of \code{\link[rGEDI:readLevel2B]{readLevel2B}} function).
#'An S4 object of class "gedi.level2b".
#'
#'@return Returns an S4 object of class \code{\link[data.table:data.table]{data.table-class}}
#'containing the elevation and relative heights.
#'
#'@seealso https://lpdaac.usgs.gov/products/gedi02_bv001/
#'
#'@details Characteristics. Flag indicating likely invalid waveform (1=valid, 0=invalid).
#'\itemize{
#'\item \emph{beam} Beam identifie
#'\item \emph{shot_number} Shot number
#'\item \emph{algorithmrun_flag} The L2B algorithm is run if this flag is set to 1 indicating data have sufficient waveform fidelity for L2B to run
#'\item \emph{l2b_quality_flag} L2B quality flag
#'\item \emph{delta_time} Transmit time of the shot since Jan 1 00:00 2018
#'\item \emph{lat_lowestmode} Latitude of center of lowest mode
#'\item \emph{lon_lowestmode} Longitude of center of lowest mode
#'\item \emph{elev_highestreturn} Elevation of highest detected return relative to reference ellipsoid
#'\item \emph{elev_lowestmode} Elevation of center of lowest mode relative to reference ellipsoid
#'\item \emph{height_lastbin} Height of the last bin of the pgap_theta_z, relative to the ground
#'\item \emph{pai_z} Plant Area Index profile
#'}
#'
#'@examples
#'# Specifying the path to GEDI level2B data (zip file)
#'outdir = tempdir()
#'level2B_fp_zip <- system.file("extdata",
#'                   "GEDI02_B_2019108080338_O01964_T05337_02_001_01_sub.zip",
#'                   package="rGEDI")
#'
#'# Unzipping GEDI level2A data
#'level2Bpath <- unzip(level2B_fp_zip,exdir = outdir)
#'
#'# Reading GEDI level2B data (h5 file)
#'level2b<-readLevel2B(level2Bpath=level2Bpath)
#'
#'# Extracting GEDI Plant Area Index (PAI) Profile (GEDI Level2B)
#'level2BPAIProfile<-getLevel2BPAIProfile(level2b)
#'head(level2BPAIProfile)
#'
#'close(level2b)
#'@import hdf5r
#'@import utils
#'@importFrom hdf5r H5File
#'@export
getLevel2BPAIProfile<-function(level2b){
  level2b<-level2b@h5
  groups_id<-grep("BEAM\\d{4}$",gsub("/","",
                                     hdf5r::list.groups(level2b, recursive = F)), value = T)
  m.dt<-data.table::data.table()
  pb <- utils::txtProgressBar(min = 0, max = length(groups_id), style = 3)
  i.s=0
  for ( i in groups_id){
    i.s<-i.s+1
    utils::setTxtProgressBar(pb, i.s)
    level2b_i<-level2b[[i]]
    m<-data.table::data.table(
      beam<-rep(i,length(level2b_i[["shot_number"]][])),
      shot_number=level2b_i[["shot_number"]][],
      algorithmrun_flag=level2b_i[["algorithmrun_flag"]][],
      l2b_quality_flag=level2b_i[["l2b_quality_flag"]][],
      delta_time=level2b_i[["geolocation/delta_time"]][],
      lat_lowestmode=level2b_i[["geolocation/lat_lowestmode"]][],
      lon_lowestmode=level2b_i[["geolocation/lon_lowestmode"]][],
      elev_highestreturn=level2b_i[["geolocation/elev_highestreturn"]][],
      elev_lowestmode=level2b_i[["geolocation/elev_lowestmode"]][],
      height_lastbin=level2b_i[["geolocation/height_lastbin"]][],
      height_bin0=level2b_i[["geolocation/height_bin0"]][],
      pai_z=t(level2b_i[["pai_z"]][,1:level2b_i[["pai_z"]]$dims[2]]))
    m.dt<-rbind(m.dt,m)
  }
  colnames(m.dt)<-c("beam","shot_number","algorithmrun_flag",
                    "l2b_quality_flag","delta_time","lat_lowestmode",
                    "lon_lowestmode","elev_highestreturn",
                    "elev_lowestmode","height_lastbin",
                    "height_bin0",paste0("pai_z",seq(0,30*5,5)[-31],"_",seq(5,30*5,5),"m"))
  close(pb)
  return(m.dt)
}