R/pvsRequest6.R

pvsRequest6 <-
	function (request,inputs) {
		pvs.key <- getPVS_key()
		pvs.url <- paste("http://api.votesmart.org/",request,"key=",pvs.key,inputs,sep="") #generate url for request
		
		httpresp <- GET(url=pvs.url)
		xmltext <- content(x=httpresp, as="text")
		errors <-  getXMLErrors(xmltext) # check if xml can be parsed properly
		
		if (length(errors) != 0) {
			if (names(errors[[1]]$code) == "XML_ERR_CDATA_NOT_FINISHED") { # if not, try to fix 
				xmltext <- gsub(pattern="\003", replacement="", x=xmltext, fixed=TRUE)
			}
		}
		
		output.base <- xmlRoot(xmlTreeParse(xmltext, useInternalNodes=TRUE))
		if (names(output.base)[1]=="errorMessage") {

			# if the requested data is not available, return an empty (NA) data frame and give a warning
			warning(gsub(pattern="&", replacement=" ", x=paste("No data available for: ", inputs,". The corresponding rows in the data frame are filled with NAs.", sep=""), fixed=TRUE), call.=FALSE)
			output.df <- data.frame(matrix(nrow=1,ncol=0), stringsAsFactors = FALSE)
			output.df
		} else {

			output <- output.base
			nodenames <- unique(names(output)) # get names of nodes
			freq.names <- summary(as.factor(names(output))) # check frequency, 
			
			
			# if there are some nodes with one entry, and others with many, the ones with one contain data that belongs to every single entry of the one
			# with several entries (like invariant variable over different observations, --> makrodata)

			# check if there are several nodes with the same name
			if (sum(freq.names)>length(nodenames)) { 
				
				freq0 <- unique(names(freq.names[freq.names==0]))
				freq1 <- unique(names(freq.names[freq.names==1]))
				freqh <- unique(names(freq.names[freq.names>1]))
				# ignore generalInfo:
				freq1b <- freq1[freq1!="generalInfo"]

				# scrap all data from nodes that come up once, and cbind the resulting dfs
				freq1.list <- lapply(freq1b, FUN=function(i) {
					x <- output[[i]]
					data.frame(t(xmlSApply(x, xmlValue)), stringsAsFactors = FALSE)
					})
				freq1.df <- bind_cols(freq1.list)
				
				
				# remove freq1-nodes from output.
				for (i in freq1)   output <- removeChildren(output,i)
				# now scrap the remaining output
				output.list <- lapply(1:length(names(output)), FUN=function(i) {
					x <- output[[i]]
					data.frame(t(xmlSApply(x, xmlValue)), stringsAsFactors = FALSE)
					})
				output2 <- suppressWarnings(bind_rows(output.list)) # coercion to character is just fine, no warning needed
				output2 <- cbind(freq1.df, output2)
				
				return(output2)
				
			} else {
				output <- t(xmlSApply(removeChildren(output.base,kids=1), function(x) xmlSApply(x, xmlValue)))
				output.df <- data.frame(output, row.names=NULL, stringsAsFactors = FALSE)
				
				return(output.df)
			}
		}
	}
umatter/pvsR documentation built on Jan. 9, 2021, 4:35 p.m.