Question

我有一个井ID（wdid）的列表，我想从指定的网站获取它们各自的转移记录。根据适用于另一个网站上类似查询的代码，我想到了以下代码。但是，在代码“成功”运行之后，我只会得到“ 0”或“ list（）”。我也不是R和网络抓取的高级用户。有人可以帮我解决我的失踪吗？代码如下：

#Install Packages

install.packages(c("httr", "jsonlite", "lubridate"))
install.packages('stringr')

library(rvest)
library(stringr)
library(jsonlite)
library(lubridate)
options(stringsAsFactors = FALSE)

#Load External Data

Wells<-read.csv("~/file path/Wells.csv",header=TRUE)  #This is the list of the Well IDs whose diversion record I want to pull
  n=length(Wells[,1])

#Specify the URL
URL.1 <- "http://dnrweb.state.co.us/DWR/DwrApiService/api/v2/structures/divrec/divrecyear/?format=csvforced&wdid="

#Run Loop
for(i in 1:n){
  tryCatch({    #This is to keep the loop from breaking if there is an error
         wdid<-2005002 #This is the first Well ID in the list
        #Wells[i,1]

  url<-paste(URL.1,"0",wdid,sep="")

  site<-read_html(url)

  d<-html_nodes(site,"#tabs-4 table")%>%  #This finds the spot in the html I need
    html_table()                          #Because what I need is a table, this keeps in table form

  ifelse(length(d)!=0,dd<-data.frame(d,wdid),dd<-0) #The length test makes sure the record is not empty

  ifelse(i==1,output<-dd,output<-rbind(output,dd))

  Sys.sleep(0.5)
  },error=function(e){cat("ERROR :",conditionMessage(e), wdid, "\n")}) #Displays error that would have broken loop
}

temp<-output[output$wdid>0,]
output.2<-merge(Wells,temp,by.x="dataValue",by.y="wdid",all=TRUE)
write.csv(output.2,file="~/file path/records.csv")

以下是我的井号示例：

返回的输出如下：

输出 [，1] 输出0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0 dd 0

如何在rvest和stringr中从R中的网站抓取数据中遍历大量ID？

0 个答案: