R/scan_sites_metadata.R

In USGS-R/soilmoisturetools: USGS Soil Moisture Portal tools

#'@title Get SCAN station metadata
#'
#'@inheritParams scan_data
#'
#'@note This is somewhat slow. Queries over 1000 sites are split into multiple requests. 
#'I recommend querying only the specific sites you need.
#'
#'@return data frame with a row for each station. Order returned same as requested station order is not guaranteed.
#'
#'@author Luke Winslow
#'
#'@examples 
#'\dontrun{
#'scan_sites_metadata("2057:AL:SCAN")
#'}
#'@export
scan_sites_metadata = function(stationTriplets){
  
  df_out = data.frame()
  stationChunks = split(stationTriplets, ceiling(seq_along(stationTriplets)/10))
  
  for(i in 1:length(stationChunks)){
    
    cmd = xmlNode("q0:getStationMetadataMultiple")
    
    stationNodes = lapply(stationChunks[[i]], xmlNode, name="stationTriplets")
    cmd = addChildren(cmd, kids=stationNodes)
    
    body = xmlNode("SOAP-ENV:Body", cmd)
    
    root = xmlNode("SOAP-ENV:Envelope", namespaceDefinitions=c("SOAP-ENV"="http://schemas.xmlsoap.org/soap/envelope/", "q0"="http://www.wcc.nrcs.usda.gov/ns/awdbWebService", "xsd"="http://www.w3.org/2001/XMLSchema", "xsi"="http://www.w3.org/2001/XMLSchema-instance"), body)
    
    out = POST(service_url, content_type("text/soap_xml; charset-utf-8"), body=toString.XMLNode(root))
    #values = xpathSApply(content(out), '//values', xmlValue)
    
    
    df_out = rbind(df_out, xmlToDataFrame(nodes=xpathApply(content(out), '/*/*/*/return')))
  }
  
  df_out$elevation = as.numeric(df_out$elevation)
  df_out$latitude  = as.numeric(df_out$latitude)
  df_out$longitude = as.numeric(df_out$longitude)
  df_out$station   = df_out$name
  
  return(df_out)
}