提取< tr>来自多个html文件的值 [英] Extracting <tr> values from multiple html files
问题描述
我是网络报废新手。我有3000多个html / htm文件,我需要从它们中提取tr值并在数据框中进行转换以进行进一步分析。
我使用的代码是:
html< - list.files(pattern =\\。(htm | html)$)
mydata< - lapply(html,read_html)%>%
html_nodes(tr)%>%
html_text()
$ c
$ b UseMethod中的错误(xml_find_all):
没有适用于'xml_find_all'的方法应用于类character
我做错了什么?
为了提取数据框,我有这样的代码:
$ $ p $ u < - as.data.frame(matrix(mydata,byrow = TRUE),stringsAsFactors = FALSE)
预先感谢您。
lapply
会输出文件列表。不能由 read_html
处理。取而代之的是在 lapply
中包含所有 rvest
操作:
<$ p $ (html,function()()(){code> html< - list.files(pattern =\\\。。(htm | html)$)
mydata< - lapply文件){
read_html(文件)%>%html_nodes('tr')%>%html_text()
})
示例
我的WD内容中有文件
< html>
< head>< / head>
< body>
< table>
< tr>< td> Martin< / td>< / tr>
< / table>
< / body>
< / html>
和
< HTML>
< head>< / head>
< body>
< table>
< tr>< td> Carolin< / td>< / tr>
< / table>
< / body>
< / html>
会输出
> mydata
[[1]]
[1]Martin
[[2]]
[1]Carolin
在我的情况下,我可以使用
data.frame(Content = unlist(mydata))
I am new to web-scrapping. I have 3000+ html/htm files and I need to extract "tr" values from them and transform in a dataframe to do further analysis.
Codes which I have used is:
html <- list.files(pattern="\\.(htm|html)$")
mydata <- lapply(html,read_html)%>%
html_nodes("tr")%>%
html_text()
Error in UseMethod("xml_find_all") : no applicable method for 'xml_find_all' applied to an object of class "character"
What I am doing wrong?
To extract in a dataframe, i have this code
u <- as.data.frame(matrix(mydata,byrow = TRUE),stringsAsFactors = FALSE)
Thank you in advance.
lapply
will output a list of documents. That cant be handled by read_html
. Instead include all rvest
actions in lapply
:
html <- list.files(pattern="\\.(htm|html)$")
mydata <- lapply(html, function(file) {
read_html(file) %>% html_nodes('tr') %>% html_text()
})
Example
Having two test files in my WD with content
<html>
<head></head>
<body>
<table>
<tr><td>Martin</td></tr>
</table>
</body>
</html>
and
<html>
<head></head>
<body>
<table>
<tr><td>Carolin</td></tr>
</table>
</body>
</html>
would output
> mydata
[[1]]
[1] "Martin"
[[2]]
[1] "Carolin"
In my case I could then format it using
data.frame(Content = unlist(mydata))
这篇关于提取< tr>来自多个html文件的值的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!