我正在尝试在2012年奥运会维基百科内找回奖牌表。
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[[UITabBar appearance] setTintColor:[UIColor blackColor]];
[[UITabBar appearance] setSelectionIndicatorImage:[UIImage imageNamed:@"image1"]];}
xpath0或xpath1返回错误
library(rvest)
library(magrittr)
url <- "https://en.wikipedia.org/wiki/United_States_at_the_2012_Summer_Olympics"
xpath0 <- '//*[@id="mw-content-text"]/table[1]'
xpath1 <- '//*[@id="mw-content-text"]/table[2]'
xpath2 <- '//*[@id="mw-content-text"]/table[2]/tbody/tr/td[1]'
xpath3 <- '//*[@id="mw-content-text"]/table[2]/tbody/tr/td[1]/table'
tb <- url %>%
html() %>%
html_nodes(xpath=xpath0) %>%
html_nodes("") %>%
html_table()
xpath2和xpath3返回空列表。
同时我尝试使用Selectorgadget(https://cran.r-project.org/web/packages/rvest/vignettes/selectorgadget.html)指向确切的元素。我得到了
// td [(((count(preceding-sibling :: )+ 1)= 1)和parent :: )] | // * [contains(concat(“”,@ class,“”),concat(“”, “headerSortDown”,“”))]
和错误
parse_simple_selector(stream)出错: 预期的选择器,得到了
我真的很感激任何帮助。
JOA
答案 0 :(得分:1)
第一个带有名称的表格结构复杂,似乎很难转换为标准格式。至少我没有成功。
可以通过
获得运动奖牌数量和总奖牌的摘要library(rvest) #v.0.2.0.9000
url <- "https://en.wikipedia.org/wiki/United_States_at_the_2012_Summer_Olympics"
tb <- read_html(url) %>% html_node("table.wikitable:nth-child(2)") %>% html_table(fill=TRUE)
#> head(tb)
# Medals by sport NA NA NA NA NA NA
#1 Sport 01 ! 02 ! 03 ! Total NA NA
#2 Swimming 16 9 6 31 NA NA
#3 Track & field 9 12 7 28 NA NA
#4 Gymnastics 3 1 2 6 NA NA
#5 Shooting 3 0 1 4 NA NA
#6 Tennis 3 0 1 4 NA NA
然后还有另一张表格,总结了您可以获得的所有竞争对手
tb2 <- read_html(url) %>% html_node("table.wikitable:nth-child(20)") %>% html_table()
#> head(tb2)
# Sport Men Women Total
#1 Archery 3 3 6
#2 Athletics (track and field) 63 62 125
#3 Badminton 2 1 3
#4 Basketball 12 12 24
#5 Boxing 9 3 12
#6 Canoeing 5 2 7
这是多个奖牌获得者的表格:
tb3 <- read_html(url) %>% html_node("table.wikitable:nth-child(8)") %>% html_table(fill=TRUE)
#> head(tb3)
# Multiple medalists NA NA NA NA NA NA
#1 Name Sport 01 ! 02 ! 03 ! Total NA
#2 Michael Phelps Swimming 4 2 0 6 NA
#3 Missy Franklin Swimming 4 0 1 5 NA
#4 Allison Schmitt Swimming 3 1 1 5 NA
#5 Ryan Lochte Swimming 2 2 1 5 NA
#6 Allyson Felix Track & field 3 0 0 3 NA
正如@Metrics所指出的,这实际上取决于你想要的表。该页面上有许多表格。