R 循环下载联合国商品贸易统计数据

编程问答 2022-05-23

问题描述

我正在尝试下载 UN ComTrade 数据集。 当然，这是一个巨大的文件，因此我需要将其拆分为许多文件（我认为将每个记者国家和商品分开），但我仍然找不到合适的解决方案。 然而，我已经尝试了本主题 Writing a loop to extract Comtrade data and export them into multiple csv files 中的建议，这似乎适合我的情况，但没有结果，因为我不断收到以下错误消息：

Error in file(file,"rt") : 
cannot open the connection to 'http://comTrade.un.org/api/get?max=50000&type=C&freq=M&px=HS&ps=all&r=American Samoa&p=0&rg=2&cc=842520&fmt=csv'
Inoltre: Warning message:
In file(file,"rt") :

Error in file(file,"rt") : 
cannot open the connection to 'http://comTrade.un.org/api/get?max=50000&type=C&freq=M&px=HS&ps=all&r=American Samoa&p=0&rg=2&cc=842520&fmt=csv'

无论如何，以下是我从此刻起遵循的步骤。

## Stefan A's code
    get.ComTrade <- function(url="http://comTrade.un.org/api/get?",maxrec=50000,type="C",freq="A",px="HS",ps="Now",r,p,rg="all",cc="TOTAL",fmt="json"
               )
          {
         string<- paste(url,"max=",maxrec,"&" #maximum no. of records returned,"type=",type,"&" #type of Trade (c=commodities),"freq=",freq,"&" #frequency,"px=",px,"&" #classification,"ps=",ps,"&" #time period,"r=","&" #reporting area,"p=","&" #partner country,"rg=",rg,"&" #Trade flow,"cc=",cc,"&" #classification code,"fmt=",fmt        #Format,sep = ""
          )

      if(fmt == "csv") {
           raw.data<- read.csv(string,header=TRUE)
           return(list(validation=NULL,data=raw.data))
           } else {
           if(fmt == "json" ) {
           raw.data<- fromJSON(file=string)
           data<- raw.data$dataset
           validation<- unlist(raw.data$validation,recursive=TRUE)
           ndata<- NULL
     if(length(data)> 0) {
           var.names<- names(data[[1]])
           data<- as.data.frame(t( sapply(data,rbind)))
           ndata<- NULL
  
     for(i in 1:ncol(data)){
      data[sapply(data[,i],is.null),i]<- NA
      ndata<- cbind(ndata,unlist(data[,i]))
     }
      ndata<- as.data.frame(ndata)
      colnames(ndata)<- var.names
     }
      return(list(validation=validation,data =ndata))
     }
   }
  }

然后，我从以下位置获得记者名单：

   library(rjson)
   string <- "http://comTrade.un.org/data/cache/partnerAreas.json"
   reporters <- fromJSON(file=string)
   reporters <- as.data.frame(t(sapply(reporters$results,rbind)))

因此，我清理了报告者列表，以避免出现无数据行的问题。

  ls_reporters <- reporters[ ! reporters$V2 %in% c("Africa CAMEU region,not elsewhere specified","Areas,"CACM,"Caribbean,"Eastern Europe,"Europe EFTA,"Europe EU,"LAIA,"north America,the Caribbean and Central America not elsewhere specified","northern Africa,"Oceania,"Other Africa,"Other Asia,"Other Europe,"Rest of America,"Western Asia,not elsewhere specified"),]

最后，我继续建议的循环。

  for (i in 1:length(country_list)){  
  d <- get.ComTrade(r="i",p="all",ps="2006",rg="2",freq="A")
  df <-  cbind(d$data[2],d$data[10],d$data[13],d$data[32])
  df$million <- as.numeric(as.character(df[,4]))/1000000
  myfile <- file.path("~/working directory",paste0("_",i,".csv"))
  write.table(df,file=myfile,na = "NA",row.names = FALSE,col.names = FALSE,quote=FALSE,append=FALSE,sep="")
  }

再次，结果就是上面的错误信息。 有什么提示吗？

解决方法

暂无找到可以解决该程序问题的有效方法，小编努力寻找整理中！

如果你已经找到好的解决方法，欢迎将解决方案带上本链接一起发送给小编。

小编邮箱:dio#foxmail.com (将#修改为@）

dataframedownloadloopsrr