使用R网络抓取数据

目标：我试图从网页http://www.nepalstock.com/datanepse/previous.php中取消所有公司的历史日常股票价格。以下代码有效;但是，它只会生成最近（2015年2月5日）日期的每日股价。换句话说，输出是一样的，不管我输入的日期如何。如果你能在这方面提供帮助，我将不胜感激。使用R网络抓取数据

library(RHTMLForms) 
    library(RCurl) 
    library(XML) 
    url <- "http://www.nepalstock.com/datanepse/previous.php" 
    forms <- getHTMLFormDescription(url) 

    # we are interested in the second list with date forms 
    # forms[[2]] 
    # HTML Form: http://www.nepalstock.com/datanepse/ 
    # Date: [ ] 

    get_stock<-createFunction(forms[[2]]) 

#create sequence of dates from start to end and store it as a list 

    date_daily<-as.list(seq(as.Date("2011-08-24"), as.Date("2011-08-30"), "days")) 

# determine the number of elements in the list 

    num<-length(date_daily) 

    daily_1<-lapply(date_daily,function(x){ 
     show(x) #displays the particular date 
     readHTMLTable(htmlParse(get_stock(Date = x)), which = 7) 

    }) 


#18 tables out of which 7 is one what we desired 

# change the colnames 

    col_name<-c("SN","Traded_Companies","No_of_Transactions","Max_Price","Min_Price","Closing_Price","Total_Share","Amount","Previous_Closing","Difference_Rs.") 
    daily_2<-lapply(daily_1,setNames,nm=col_name) 

Output: 
> head(daily_2[[1]],5) 
SN         Traded_Companies No_of_Transactions Max_Price Min_Price Closing_Price Total_Share Amount 
1 1     Agricultural Development Bank Ltd     24  489  471   473  2,868 1,359,038 
2 2 Arun Valley Hydropower Development Company Limited     40  365  360   362  8,844 3,199,605 
3 3     Alpine Development Bank Limited     11  297  295   295   150 44,350 
4 4     Asian Life Insurance Co. Limited     10  1,230  1,215   1,225   898 1,098,452 
5 5       Apex Development Bank Ltd.     23  131  125   131  6,033 769,893 
    Previous_Closing Difference_Rs. 
1    480    -7 
2    363    -1 
3    303    -8 
4   1,242   -17 
5    132    -1 
> tail(daily_2[[1]],5) 
    SN     Traded_Companies No_of_Transactions Max_Price Min_Price Closing_Price Total_Share Amount Previous_Closing 
140 140    United Finance Ltd     4  255  242   242   464 115,128    255 
141 141 United Insurance Co.(Nepal)Ltd.     3  905  905   905   234 211,770    915 
142 142   Vibor Bikas Bank Limited     7  158  152   156   710 109,510    161 
143 143 Western Development Bank Limited     35  320  311   313  7,631 2,402,497    318 
144 144 Yeti Development Bank Limited     22  139  132   139  14,355 1,921,511    134 
    Difference_Rs. 
140   -13 
141   -10 
142    -5 
143    -5 
144    5

来源

2015-02-07 Metrics

这里有一个快速的方法。请注意，该站点使用POST请求将日期发送到服务器。

library(rvest) 
library(httr) 

page <- "http://www.nepalstock.com/datanepse/previous.php" %>% 
    POST(body = list(Date = "2015-02-01")) %>% 
    html() 

page %>% 
    html_node(".dataTable") %>% 
    html_table(header = TRUE)

来源

2015-02-07 14:39:29 hadley

谢谢@Hadley的解决方案。我必须学习新的软件包。 – Metrics 2015-02-07 15:30:57

使用R网络抓取数据

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