質問
I have this html file
https://stackoverflow.com/questions/23530237
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Russian<html>
<table width="111" >
<tr> <td> A </td>
<td> B </td>
</tr>
<tr> <td> C </td>
<td> D </td>
</tr>
</table>
<table width="222" >
<tr> <td> E </td>
<td> F </td>
</tr>
<tr> <td> G </td>
<td> H </td>
</tr>
</table>
</html>
And in R I am doing
library(XML)
tree = htmlTreeParse(file, useInternal=TRUE, asTree=TRUE)
table = getNodeSet(tree, "//table[@width='222']")[[1]]
xpathSApply(table, "//td", xmlValue)
And I'm getting
[1] " A " " B " " C " " D " " E " " F " " G " " H "
whereas I was hopping to get
[1] " E " " F " " G " " H "
I can't understand what's going on
解決
Just do it like that:
# Load libraries
library(XML)
# Load data
base_html <- "<html><table width='111'><tr><td>A</td><td>B</td></tr><tr><td>C</td><td>D</td></tr></table><table width='222'><tr><td>E</td><td>F</td></tr><tr><td>G</td><td>H</td></tr></table></html>"
# Parse HTML
tree <- htmlTreeParse(base_html, useInternal=TRUE, asTree=TRUE)
# Get data
xpathSApply(tree, "//table[@width='222']/tr/td", xmlValue)
他のヒント
Using your current method, you can get the values with this. By the way, you may not want to assign the name table to anything, as it's a base R function and might cause trouble down the line. No need for Rcurl either.
> library(XML)
> doc <- '<html>
<table width="111" >
<tr> <td> A </td>
<td> B </td>
</tr>
<tr> <td> C </td>
<td> D </td>
</tr>
</table>
<table width="222" >
<tr> <td> E </td>
<td> F </td>
</tr>
<tr> <td> G </td>
<td> H </td>
</tr>
</table>
</html>'
> tree <- htmlTreeParse(doc, useInternal = TRUE, asTree = TRUE)
> tab <- getNodeSet(tree, "//table[@ width='222']")[[1]]
> xpathSApply(tab, "//table[@width='222']/tr/td", xmlValue)
[1] " E " " F " " G " " H "
Alternatively, you could do
> tab2 <- getNodeSet(tree, "//table")[[2]]
> xpathSApply(tab2, "//table[@width='222']/tr/td", xmlValue)
[1] " E " " F " " G " " H "
