R/pvsRequestDetailedBio.R

In pvsR: An R package to interact with the Project Vote Smart API for scientific research

pvsRequestDetailedBio <-
  function (request,inputs) {
    pvs.url <- paste("http://api.votesmart.org/",request,"key=",get('pvs.key',envir=.GlobalEnv),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") { # return empty df
      
      # 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))
      return(output.df)
      
      
    } else {
      

  output <- output.base 
  nodenames <- names(output) # get names of nodes
  
  # remove generally unnecessary child-nodes:
  
  if (nodenames[1]=="generalInfo") {
    
    output <- removeChildren(output,kids="generalInfo")
    
  } 
  
  # process detailed bio part separately
  separate <- c("education", "profession", "political", "congMembership", "orgMembership")
  candidate <- output[["candidate"]]
  
  sepl <- names(candidate) %in% separate

  # extract values for each remaining mainnode
  
  seplist <- lapply(separate, function(s) {
  
  data.frame(t(xmlSApply(candidate[[s]], function(x) xmlSApply(x, xmlValue))),row.names=NULL)

  })
  
 # give each list entry the coresponding name
  for (i in 1:length(seplist)) names(seplist)[i] <- separate[i]
   
  
  # ------- Second, the remaining nodes ---------
  
 # remove subnodes to be processed separately from main document
 output[["candidate"]] <- removeChildren(output[["candidate"]], kids=separate)
 
  # process rest as usual: 
  if (length(names(output))>1) {
   nonsep <- xmlSApply(output, function(x) data.frame(t(xmlSApply(x, xmlValue))))
  } else {
    nonsep <- list(data.frame(t(xmlSApply(output[[1]], xmlValue))))
    names(nonsep) <- names(output)
  }
 
 # return dfs in list
 output.list <- c(nonsep,seplist)
 
 # add empty dfs if some parts are missing
 dfn <- names(output.list)
 
 pseudo.output <- list(
   candidate=data.frame(candidateId=NA),
   office=data.frame(name=NA),
   education=data.frame(degree=NA),
   profession=data.frame(title=NA),
   political=data.frame(title=NA),
   congMembership=data.frame(title=NA),
   orgMembership=data.frame(title=NA)
 )
 nitems <- 1:length(pseudo.output)
 missing <- !(names(pseudo.output) %in% dfn) # missing nodes
 
 output.list <- c(output.list, pseudo.output[ nitems[missing]] )
 output.list <- output.list[names(pseudo.output)]
 
 empty <- lapply(output.list,ncol)==0 # empty nodes
 output.list[empty] <- pseudo.output[empty]
  
 return(output.list)
 }
  
  
}