用R颳去維基百科做出清單和數據框

Question

我想刮Vancouver olympic games維基百科條目。不幸的是它不是一個很好的表格格式

我想創建一個有2列的數據框：Nation和number of athletes。

在這一點上我有

library(XML) 
library(RCurl) 

path<-"https://fr.wikipedia.org/wiki/Jeux_olympiques_d%27hiver_de_2010" 
webpage <- getURL(path) 
webpage <- readLines(tc <- textConnection(webpage)); close(tc) 

pagetree <- htmlTreeParse(webpage, error=function(...){}, useInternalNodes = TRUE) 

# Extract table header and contents 
tablehead <- xpathSApply(pagetree, "//*/table/tr", xmlValue) 
country<-tablehead[31] 

其中國家

> country 
[1] "\n Afrique du Sud (2)\n Albanie (1)\n Algérie (1)\n Allemagne (153)\n Andorre (6)\n Argentine (7)\n Arménie (4)\n Australie (41)\n Autriche (82)\n Azerbaïdjan (2)\n Belgique (8)\n Bermudes (1)\n Biélorussie (50)\n Bosnie-Herzégovine (5)\n Brésil (5)\n Bulgarie (18)\n Canada (206)\n Chili (3)\n Chine (90)\n Chypre (2)\n Colombie (1)\n\n\n\n Corée du Nord (2)\n Corée du Sud (46)\n Croatie (18)\n Danemark (18)\n Espagne (18)\n Estonie (32)\n États-Unis (216)\n Éthiopie (1)\n Finlande (95)\n France (108)\n Géorgie (12)\n Ghana (1)\n Grande-Bretagne (52)\n Grèce (7)\n Hong Kong (1)\n Hongrie (16)\n Îles Caïmans (1)\n Inde (3)\n Iran (4)\n Irlande (6)\n Islande (4)\n\n\n\n Israël (3)\n Italie (109)\n Jamaïque (1)\n Japon (94)\n Kazakhstan (38)\n Kirghizistan (2)\n Lettonie (54)\n Liban (3)\n Liechtenstein (6)\n Lituanie (6)\n Macédoine (3)\n Moldavie (8)\n Maroc (1)\n Mexique (1)\n Monaco (3)\n Monténégro (1)\n Mongolie (2)\n Népal (1)\n Norvège (99)\n Nouvelle-Zélande (16)\n\n\n\n Ouzbékistan (3)\n Pakistan (1)\n Pays-Bas (34)\n Pérou (3)\n Pologne (50)\n Portugal (1)\n République tchèque (93)\n Roumanie (29)\n Russie (179)\n Saint-Marin (1)\n Sénégal (1)\n Serbie (10)\n Slovaquie (73)\n Slovénie (49)\n Suède (108)\n Suisse (146)\n Tadjikistan (1)\n Taipei chinois (1)\n Turquie (5)\n Ukraine (47)\n\n" 

我已經試過

str_detect(country,"\n") 
country<-str_split(country,"\n") 

，但數據是非常髒，而且它不工作很好。有什麼建議麼？

Answer 1

可能性是使用正則表達式。我從來沒有做過有R但stringr似乎被推薦圖書館： Extract a regular expression match in R version 2.10（http://cran.r-project.org/web/packages/stringr/stringr.pdf）

編輯：出現代碼爲我

library(XML) 
library(RCurl) 
options(RCurlOptions = list(cainfo = system.file("CurlSSL", "cacert.pem", package = "RCurl"))) 
library(stringr) 

path<-"https://fr.wikipedia.org/wiki/Jeux_olympiques_d%27hiver_de_2010" 
webpage <- getURL(path) 
webpage <- readLines(tc <- textConnection(webpage)); close(tc) 

pagetree <- htmlTreeParse(webpage, error=function(...){}, useInternalNodes = TRUE, encoding = "UTF-8") 
# Extract table header and contents 
tablehead <- xpathSApply(pagetree, "//*/table/tr", xmlValue) 
country<-tablehead[31] 

country<-strsplit(country,"\n") 

# extract country 
bar <- function(x) str_trim(str_extract(x, "[^(]*"), side = "both") 
res1 <- sapply(country[[1]], bar)  
# extract nb of athletes 
foo <- function(x) str_trim(str_match(x, "\\((.*?)\\)")[[2]], side = "both") 
res2 <- sapply(country[[1]], foo) 
# build df 
res2 <- as.numeric(res2) 
df <- data.frame(res1, res2) 
df <- df[res1 != "",] 
# inspect df 
nrow(df) 
summary(df) 

Answer 2

工作嘗試

library(plyr) 
country <- str_split(country,"\n")[[1]] 
df <- ldply(country[[1]], function(z) data.frame(str_extract(z, "[A-Za-z]+")[[1]], str_extract(z, "[0-9]+"))) 
head(na.omit(df)) 

            a      b 
2       Afrique      2 
3       Albanie      1 
4        Alg      1 
5       Allemagne      153 
6       Andorre      6 
7       Argentine      7