硒刮板 - 编程之家

如何解决硒刮板

我想提取位于“https://www.chess.com/member/magnuscarlsen”的“已完成游戏”表中的数据。

下面的代码给了我一个大小为 0 的列表。Selenium 方面的事情似乎正在起作用。 Firefox 浏览器在我的桌面上打开并导航到该页面。任何帮助将不胜感激。我已经无能为力了！

rD <- rsDriver(browser="firefox",port=4442L,verbose=F)
remDr <- rD[["client"]]

remDr$navigate("https://www.chess.com/member/magnuscarlsen")

Sys.sleep(5) # give the page time to fully load
html <- remDr$getPageSource()[[1]]

html <- read_html(html)

signal <- html %>%
  html_nodes("table.table-component table-hover archived-games-table")

解决方法

这是一种可以轻松解决您的问题的方法，因为页面本身只有一个表格。使用 rvest 轻松将其取出。请注意，我使用管道是因为我更喜欢它们。你当然可以不用它们。

library(RSelenium)
library(rvest)

rD <- rsDriver(browser="firefox",port=4443L,verbose=F)
remDr <- rD[["client"]]

remDr$navigate("https://www.chess.com/member/magnuscarlsen")

Sys.sleep(5) # give the page time to fully load
html <- remDr$getPageSource()[[1]]

html <- read_html(html)

##required table
html %>% html_table() %>% .[[1]]

1 如果您不介意没有准确度数据（我认为没有公布的计算基础），请查看 public APIs from Chess.com。你确实得到了所有的动作信息。

特别是通过 BigChess 包的实现。我从下面修改了示例：

所有游戏：

library(rjson)
library(bigchess)

user <- "magnuscarlsen"
json_file <- paste0("https://api.chess.com/pub/player/",user,"/games/archives")
json_data <- fromJSON(paste(readLines(json_file),collapse = ""))
result <- data.frame()
for(i in json_data$archives)
  result <- rbind(result,read.pgn(paste0(i,"/pgn")))

单月：

library(bigchess)

df <- read.pgn("https://api.chess.com/pub/player/magnuscarlsen/games/2020/12/pgn")
print(df[df$Date == '2020.12.11'])

根据要求添加您的准确度。该页面上的大部分信息实际上都可以通过 API 获得：


library(bigchess)
#> Warning: package 'bigchess' was built under R version 4.0.3
library(purrr)
library(jsonlite)
#> Warning: package 'jsonlite' was built under R version 4.0.3
#> 
#> Attaching package: 'jsonlite'
#> The following object is masked from 'package:purrr':
#> 
#>     flatten
library(stringr)

try_again <- function(link) {  #https://blog.r-hub.io/2020/04/07/retry-wheel/
  maxtry <- 5
  try <- 1
  resp <- read_json(link)
  while (try <= maxtry && is.null(resp$data)) {
    resp <- read_json(.)
    try <- try + 1
    Sys.sleep(try * .25)
  }
  return(resp)
}

url <- "https://api.chess.com/pub/player/magnuscarlsen/games/2020/12"
result <- data.frame()
result <- read.pgn(paste0(url,"/pgn"))
#> Warning in readLines(con): incomplete final line found on 'https://
#> api.chess.com/pub/player/magnuscarlsen/games/2020/12/pgn'
#> 2021-02-15 20:29:04,successfully imported 47 games
#> 2021-02-15 20:29:04,N moves computed
#> 2021-02-15 20:29:04,extract moves done
#> 2021-02-15 20:29:04,stat moves computed
result <- filter(result,result$Date == "2020.12.11")

data <- read_json(url)
mask <- map(data$games,~ !is.na(str_match(.x$pgn,'UTCDate\\s\\"2020\\.12\\.11')[,1])) %>% unlist()
games <- data$games[mask]
games <- paste0("https://www.chess.com/callback/analysis/game/live/",map(games,~ str_match(.x$url,"\\d+")[,1]),"/all")

df <- map_df(games,~ {
  json_data <- try_again(.x)
  tryCatch(
    data.frame(
      Url = .x,WhiteAccuracy = json_data$data$analysis$CAPS$white$all,BlackAccuracy = json_data$data$analysis$CAPS$black$all,stringsAsFactors = FALSE
    ),error = function(e) {
      data.frame(
        Url = .x,WhiteAccuracy = NA_integer_,BlackAccuracy = NA_integer_,stringsAsFactors = FALSE
      )
    }
  )
})

final <- cbind(result,df)
#> Error in .cbind.ts(list(...),.makeNamesTs(...),dframe = FALSE,union = TRUE): non-time series not of the correct length

^{由 reprex package (v0.3.0) 于 2021 年 2 月 15 日创建}