如何用R替换url中的一个部分 [英] how to replace one part in url by using R

问题描述

目前我有网站

http://www.amazon.com/Apple-generation-Tablet-processor-White/product-reviews/B0047DVWLW/ref=cm_cr_pr_btm_link_2?ie=UTF8&pageNumber=1&showViewpoints=0&sortBy=bySubmissionDateDescending

我想替换此部分

pageNumber = 1

被一系列数字替换，例如1,2,3，..... n

我知道我需要使用粘贴功能。但是我可以找到这个数字并将其替换吗？

解决方案

您可以使用 parseQueryString 闪亮的包或 parse_url 和 build_url c>从 httr 包。

  require（闪亮）
 testURL<  - < http：//www.amazon.com/Apple-generation-Tablet-processor-White/product-reviews/B0047DVWLW/ref=cm_cr_pr_btm_link_2？ie = UTF8&pageNumber = 1& showViewpoints = 0& sortBy = bySubmissionDateDescending>中
 parseURL<  -  parseQueryString（testURL）
 parseURL $ pageNumber<  -  4 
 newURL<  -  paste（names（parseURL），parseURL，sep ==，collapse =& amp ;）
 
 require（httr）
 testURL<  - < http：//www.amazon.com/Apple-generation-Tablet-processor-White/product-reviews/ B0047DVWLW / REF = cm_cr_pr_btm_link_2即= UTF8&安培; PAGENUMBER = 1&安培; showViewpoints = 0&安培; sortBy = bySubmissionDateDescending>中
 parseURL<  -  parse_url（testURL）
 parseURL $ query $ pageNumber<  -  4 
 newURL<  -  build_url（parseURL）
  pre> 
Currently I have the website

http://www.amazon.com/Apple-generation-Tablet-processor-White/product-reviews/B0047DVWLW/ref=cm_cr_pr_btm_link_2?ie=UTF8&pageNumber=1&showViewpoints=0&sortBy=bySubmissionDateDescending

I want to replace this part 

pageNumber=1

to be replaced with a sequence of numbers such as 1,2,3,.....n

I know I need to use the paste function. But can do I locate this number and replace it?
解决方案
You can use the parseQueryString function from the shiny package or parse_url and build_url from httr package.
require(shiny)
testURL <- "<http://www.amazon.com/Apple-generation-Tablet-processor-White/product-reviews/B0047DVWLW/ref=cm_cr_pr_btm_link_2?ie=UTF8&pageNumber=1&showViewpoints=0&sortBy=bySubmissionDateDescending>"
parseURL <- parseQueryString(testURL)
parseURL$pageNumber <- 4
newURL <- paste(names(parseURL), parseURL, sep = "=", collapse="&")

require(httr)
testURL <- "<http://www.amazon.com/Apple-generation-Tablet-processor-White/product-reviews/B0047DVWLW/ref=cm_cr_pr_btm_link_2?ie=UTF8&pageNumber=1&showViewpoints=0&sortBy=bySubmissionDateDescending>"
parseURL <- parse_url(testURL)
parseURL$query$pageNumber <- 4
newURL <- build_url(parseURL)


                        
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