R: How to get parent attributes and node values at the site time?

Question

I have a html and a R code like these and need to relate each node value to its parent id in a data.frame. There are some different information available for each person. ``` example <- "

555-5555

jhon@123.com

123-4567

maria@gmail.com

987-6543

32

New York

" doc = htmlTreeParse(example, useInternalNodes = T) values <- xpathSApply(doc, "//*[@class='person']/div", xmlValue) variables <- xpathSApply(doc, "//*[@class='person']/div", xmlGetAttr, 'class') id <- xpathSApply(doc, "//*[@class='person']", xmlGetAttr, 'id') # The problem: create a data.frame(id,variables,values) ``` With `xpathSApply()`, I can get phone, email, and age values as well as person attributes (id) too. However, those information come isolated and I…

Accepted Answer

In general its not going to be easy:

```
idNodes <- getNodeSet(doc, "//div[@id]")
ids <- lapply(idNodes, function(x) xmlAttrs(x)['id'])
values <- lapply(idNodes, xpathApply, path = './div[@class]', xmlValue)
attributes <- lapply(idNodes, xpathApply, path = './div[@class]', xmlAttrs)
do.call(rbind.data.frame, mapply(cbind, ids, values, attributes))
  V1              V2    V3
1  1        555-5555 phone
2  1    jhon@123.com email
3  2        123-4567 phone
4  2 maria@gmail.com email
5  3        987-6543 phone
6  3              32   age
7  3        New York  city
```

The above will give you attribute and value pairs assumming they are nested in a `div` with an associated `id`.

UPDATE: if you want to wrap it in an xpathApply type call

```
utilFun <- function(x){
  id <- xmlGetAttr(x, 'id')
  values <- sapply(xmlChildren(x, omitNodeTypes = "XMLInternalTextNode"), xmlValue)
  attributes <- sapply(xmlChildren(x, omitNodeTypes = "XMLInternalTextNode"), xmlAttrs)
  data.frame(id = id, attributes = attributes, values = values, stringsAsFactors = FALSE)
}
res <- xpathApply(doc, '//div[@id]', utilFun)
do.call(rbind, res)
  id attributes          values
1  1      phone        555-5555
2  1      email    jhon@123.com
3  2      phone        123-4567
4  2      email maria@gmail.com
5  3      phone        987-6543
6  3        age              32
7  3       city        New York
```

R: How to get parent attributes and node values at the site time?

Solution

Problem