polyStatsLevel2BVPM(level2BVPM, func, id=NULL)

# 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)

# Specifying the path to shapefile
polygon_filepath <- system.file("extdata", "stands_cerrado.shp", package="rGEDI")

# Reading shapefile as SpatialPolygonsDataFrame object
library(raster)
polygon_spdf<-shapefile(polygon_filepath)

# Extracting GEDI Canopy Cover and Vertical Profile Metrics
level2BVPM<-getLevel2BVPM(level2b)
head(level2BVPM)

# Clipping GEDI data by geometry
level2BVPM_clip = clipLevel2BVPMGeometry(level2BVPM, polygon_spdf, split_by="id")

# Define your own function
mySetOfMetrics = function(x)
{
metrics = list(
   min =min(x), # Min of x
   max = max(x), # Max of x
   mean = mean(x), # Mean of x
   sd = sd(x)# Sd of x
 )
 return(metrics)
}

# Computing the max of the Total Plant Area Index
pai_max<-polyStatsLevel2BVPM(level2BVPM_clip,func=max(pai), id=NULL)
pai_max

# Computing the max of the Total Plant Area Index stratified by polygon
pai_max_poly<-polyStatsLevel2BVPM(level2BVPM_clip,func=max(pai), id="poly_id")
head(pai_max_poly)

# Computing the serie of statistics of canopy cover stratified by polygon
cover_metrics<-polyStatsLevel2BVPM(level2BVPM_clip,func=mySetOfMetrics(cover),
                     id=level2BVPM_clip$id)
head(cover_metrics)
close(level2b)