[R] Reading XML attriutes in R

[Ben Tupper]

Hi,

There might be an easy solution out there already, but I suspect that you will need to parse the XML yourself.  The example below uses package xml2 not XML but you could do this with either.  The example simply shows how to get values out of the XML hierarchy.  Once you have the attributes you want in hand you can assemble the elements into a data frame (or a tibble from package tibble.)
 
By the way, I had to prepend your example with '<current>'

Cheers,
Ben

### START

library(tidyverse)
library(xml2)

txt <- "<current><city id=\"2643743\" name=\"London\"><coord lon=\"-0.13\" lat=\"51.51\"/><country>GB</country><sun rise=\"2017-01-30T07:40:36\" set=\"2017-01-30T16:47:56\"/></city><temperature value=\"280.15\" min=\"278.15\" max=\"281.15\" unit=\"kelvin\"/><humidity value=\"81\" unit=\"%\"/><pressure value=\"1012\" unit=\"hPa\"/><wind><speed value=\"4.6\" name=\"Gentle Breeze\"/><gusts/><direction value=\"90\" code=\"E\" name=\"East\"/></wind><clouds value=\"90\" name=\"overcast clouds\"/><visibility value=\"10000\"/><precipitation mode=\"no\"/><weather number=\"701\" value=\"mist\" icon=\"50d\"/><lastupdate value=\"2017-01-30T15:50:00\"/></current>"

x <- read_xml(txt)

windspeed <- x %>% 
    xml_find_first("wind/speed") %>% 
    xml_attrs()
    
winddir <- x %>% 
    xml_find_first("wind/direction") %>% 
    xml_attrs()
    
windspeed
#          value            name 
#          "4.6" "Gentle Breeze" 

winddir
#  value   code   name 
#  "90"    "E" "East" 

### END



> On Apr 27, 2017, at 6:08 AM, Archit Soni <soni.archit1989 at gmail.com> wrote:
> 
> Hi All,
> 
> I have a XML file like :
> 
> <city id="2643743" name="London">
> <coord lon="-0.13" lat="51.51"/>
> <country>GB</country>
> <sun rise="2017-01-30T07:40:36" set="2017-01-30T16:47:56"/>
> </city>
> <temperature value="280.15" min="278.15" max="281.15" unit="kelvin"/>
> <humidity value="81" unit="%"/>
> <pressure value="1012" unit="hPa"/>
> <wind>
> <speed value="4.6" name="Gentle Breeze"/>
> <gusts/>
> <direction value="90" code="E" name="East"/>
> </wind>
> <clouds value="90" name="overcast clouds"/>
> <visibility value="10000"/>
> <precipitation mode="no"/>
> <weather number="701" value="mist" icon="50d"/>
> <lastupdate value="2017-01-30T15:50:00"/>
> </current>
> 
> I want to create a data frame out of this XML but
> obviously xmlToDataFrame() is not working.
> 
> It has dynamic attributes like for node precipitation , it could have
> attributes like value and mode both if there is ppt in some city.
> 
> My basic issue now id to read XML attributes of different nodes and convert
> it into a data frame, I have scraped many forums but could not find any
> help in this.
> 
> For starters, please suggest a solution to parse the value of city node and
> corresponding id, name, lat, long etc.
> 
> I know I am asking a lot, thanks for reading and cheers! :)
> 
> -- 
> Regards
> Archit
> 
> 	[[alternative HTML version deleted]]
> 
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Ben Tupper
Bigelow Laboratory for Ocean Sciences
60 Bigelow Drive, P.O. Box 380
East Boothbay, Maine 04544
http://www.bigelow.org