R/internal_opendap.R

In modisfast: Fast and Efficient Access to MODIS Earth Observation Data

#' @name .getTimeIndex_modisVnp
#' @title get MODIS/VIIRS time index closest to actual provided date
#' @noRd

.getTimeIndex_modisVnp<-function(date,timeVector){
  date_julian<-as.integer(difftime(date ,"2000-01-01" , units = c("days")))
  index_opendap_closest_to_date<-which.min(abs(timeVector-date_julian))
  days_sep_from_date<-timeVector[index_opendap_closest_to_date]-date_julian
  if(days_sep_from_date<=0){
    index_opendap_closest_to_date<-index_opendap_closest_to_date-1
  } else {
    index_opendap_closest_to_date<-index_opendap_closest_to_date-2
  }

  date_closest_to_date<-as.Date("2000-01-01")+timeVector[index_opendap_closest_to_date+1]
  days_sep_from_date<--as.integer(difftime(date ,date_closest_to_date , units = c("days")))

  return(list(date,date_closest_to_date,days_sep_from_date,index_opendap_closest_to_date))
}

#' @name .getOpenDapURL_dimensions
#' @title get opendap url dimensions
#'
#' @import purrr
#' @noRd

.getOpenDapURL_dimensions<-function(variables,timeIndex,minLat,maxLat,minLon,maxLon,odap_timeDimName,odap_lonDimName,odap_latDimName){

  dim<-NULL

  if(!is.null(timeIndex)){
  dim<-variables %>%
    purrr::map(~paste0(.x,"[",timeIndex[1],":",timeIndex[2],"][",minLat,":",maxLat,"][",minLon,":",maxLon,"]")) %>%
    unlist() %>%
    paste(collapse=",") %>%
    paste0(",",odap_timeDimName,"[",timeIndex[1],":",timeIndex[2],"],",odap_latDimName,"[",minLat,":",maxLat,"],",odap_lonDimName,"[",minLon,":",maxLon,"]")
  } else {
    dim<-variables %>%
      purrr::map(~paste0(.x,"[",minLat,":",maxLat,"][",minLon,":",maxLon,"]")) %>%
      unlist() %>%
      paste(collapse=",") %>%
      paste0(",",odap_latDimName,"[",minLat,":",maxLat,"],",odap_lonDimName,"[",minLon,":",maxLon,"]")
  }
  return(dim)
}


#' @name .getVarVector
#' @title get SRTM time name
#' @import httr
#' @noRd

.getVarVector<-function(OpenDAPUrl,variableName,credentials=NULL){

  vector_response <- vector <- NULL

  .testLogin(credentials)

  httr::set_config(httr::authenticate(user=getOption("earthdata_user"), password=getOption("earthdata_pass"), type = "basic"))
  httr::config(maxredirs=-1)
  vector_response<-httr::GET(paste0(OpenDAPUrl,".ascii?",variableName),config = list(maxredirs=-1))

  vector_response<-httr::GET(vector_response$url)

  if(vector_response$status_code!=404){

    vector<-httr::content(vector_response,"text",encoding="UTF-8")
    vector<-strsplit(vector,",")
    vector<-vector[[1]]
    vector<-stringr::str_replace(vector,"\\n","")
    vector<-vector[-1]
    vector<-as.numeric(vector)

  return(vector)

  }
}

#' @name .getVNPladswebdataname
#' @title get VNPladsweb dataset name on the opendap server for a given modis tile
#' @noRd

.getVNPladswebdataname<-function(lines,modis_tile){

   dataset_name <- . <- NULL

  #lines <- readLines(paste0(OpenDAPUrl,"catalog.xml"))
  dataset_name <- lines[which(grepl(modis_tile,lines))[1]] %>%
    gsub("\"","",.) %>%
    gsub(".*name=\\s*", "", .)

  return(dataset_name)

}