问题描述
我是新手，我正尝试在网站上开车提取信息： https://www.plugndrive.ca/electric-cars-available-in-canada/
library(rvest);library(tidyverse)
elec_url <- read_html('https://www.plugndrive.ca/electric-cars-available-in-canada/')
car_list <- elec_url %>% html_nodes('.car-title') %>% html_text() %>% tolower() %>%
gsub(' ','-',.)
price <- read_html(paste0('https://www.plugndrive.ca/pnd_evcar_cat/',car_list[[1]],'/')) %>%
html_nodes('.starting-price .value') %>% html_text() %>% sub("\\..*","",.) %>% gsub('^\\$|\\,','',.) %>%
as.numeric()
如何从电子范围ID（XPath = // * [@ id =“ content”] / section [1] / div [2] / p [2] /强/跨度）来达到42公里。
或在底部附近的“性能”选项卡中的电气ID范围（XPath = // * [@@ =“ =” performance-container“” / ul / li [3] / span [2] / text（））到达到35公里（不要问我为什么距离不相等！）
尝试基本运行时出现以下错误：
> read_html(paste0('https://www.plugndrive.ca/pnd_evcar_cat/','/')) %>%
html_nodes('//*[@id="performance-container"]/ul/li[3]/span[2]/text()') %>% html_text()
Error in tokenize(css) : Unexpected character '/' found at position 1
谢谢，这也是我的第一篇文章，请告知我是否缺少信息。
解决方法
您可以使用来获取价格：
library(rvest)
price <- elec_url %>%
html_nodes('div.inner p.price-container span.starting-price') %>%
html_text()
price
# [1] "$32,930" "$32,990" "$33,749" "$33,965" "$37,895" "$39,990"
# [7] "$41,499" "$42,495" "$42,595" "$42,760" "$43,998" "$44,590"
#[13] "$44,898" "$44,950" "$44,995" "$44,999" "$45,371"
#[19] "$55,990" "$56,469" "$66,400" "$68,550" "$69,400" "$69,900"
#[25] "$72,200" "$72,390" "$74,950" "$74,950" "$80,500" "$89,800"
#[31] "$90,000" "$109,090" "$116,090" "$122,800" "$149,900" "$173,900"
如果要将其转换为数字，则可以使用parse_number中的readr：
readr::parse_number(price)
# [1] 32930 32990 33749 33965 37895 39990 41499 42495 42595 42760
#[11] 43998 44590 44898 44950 44995 44998 44999 45371 55990 56469
#[21] 66400 68550 69400 69900 72200 72390 74950 74950 80500 89800
#[31] 90000 109090 116090 122800 149900 173900
编辑
如果您想从每个单独的汽车页面中获取电动范围和汽油范围，也许我以前错过了您想要的东西。您可以先提取所有URL，然后从中获取数字。
library(tidyverse)
all_urls <- elec_url %>% html_nodes('div.evCar a') %>% html_attr('href')
all_ranges <- map_chr(all_urls,~.x %>%
read_html() %>% html_nodes('div.info p strong') %>%
.[1] %>% html_text())
tibble(all_ranges,car_list) %>%
mutate(electic_range = str_extract(all_ranges,'(?<=Electric Range:\\s)\\d+'),gasoline_range = str_extract(all_ranges,'(?<=Gasoline Range:\\s)\\d+')) %>%
select(-all_ranges)
# A tibble: 36 x 3
# car_list electic_range gasoline_range
# <chr> <chr> <chr>
# 1 ford-fusion-energi 42 940
# 2 toyota-prius-prime 40 995
# 3 hyundai-ioniq-phev 47 961
# 4 kia-niro-phev 42 853
# 5 volkswagen-e-golf 198 NA
# 6 mini-cooper-se 177 NA
# 7 hyundai-ioniq-electric 274 NA
# 8 subaru-crosstrek-phev 27 747
# 9 kia-soul-electric 383 NA
#10 honda-clarity-phev 77 475
# … with 26 more rows