Pachube R Functions

Pachube.R

library(rjson)
library(RCurl)

Pachube.query <- function(feed='504')
{
  json<-getURL(
    paste('http://api.pachube.com/v2/feeds/',feed,sep=''),
    netrc='optional')
  data<-fromJSON(json)
  if (data$private == "true" || !is.null(data$error)) stop(data)
  return (sapply(data$datastreams,"[[",i="id"))
}

Pachube.fetch <- function(feed='504',datastream='0',hours=6)
{
  max_range=c(0,6,12,24,5*24,14*24,31*24,90*24,180*24,365*24,365*24)
  max_value=c(0,30,60,300,900,3600,10800,21600,43200,84600)
  interval=max_value[max(which(max_range<hours))]
  start=format(Sys.time()-hours*3600+60,"%Y-%m-%dT%H:%M:%OSZ",tz="UTC")
  pages=ceiling(hours*3600/max(1,interval)/1000)
  res=matrix(nrow=0,ncol=2)
  for (p in 1:pages) {
    json<-getURL(paste(
      'http://api.pachube.com/v2/feeds/',feed,
      '/datastreams/',datastream,
      '?start=',start,
      '&page=',p,
      '&per_page=1000',
      '&interval=',interval,
      sep=''),netrc='optional')
    data<-fromJSON(json)
    if (!is.null(data$error)) stop(data)
    if (length(data$datapoints)==0) break
    m<-matrix(unlist(data$datapoints),ncol=2,byrow=T)
    res<-rbind(res,m)
  }
  return (data.frame(
    ts=strptime(res[,2],"%Y-%m-%dT%H:%M:%OS",tz="UTC"),
    val=as.numeric(res[,1])))
}