Question

I would like to import images such as this
, so that i can plot another graph over the image as described here and here.

the problem I am having is the graph is not a graphical object with a fixed url, but rather, created by code. I don’t really understand the code behind the image, but have been unable to scrape recreate it using RCurl and XML.

I see two possible options: using R to launch a browser and save image as
or processing properly the code, I imagine somehow like this

URL<-"http://
test<-htmlParese(getURL(url))
xpathSApply(

any thoughts?

Answer 1

The link to the image you want to scrape is not an “xml image”. It is simply a .png file. So, it suffices to save the image to a file, load it into R, and then put it on the plot. Something like this will get you there, but you’ll need to play with it a bit to make it pretty.

library(png)
# use the URL from your post, or construct on-the-fly
url = "http://pulse.blogs.yandex.net/?size=small&charset=utf8&period=20120116-20130116&query0=%D0%BF%D1%83%D1%82%D0%B8%D0%BD"
download.file(url,destfile='/tmp/test.png',mode='wb')
xvals=rnorm(10)
yvals=rnorm(10)
# just set up an "empty" plot
plot(xvals,yvals,type='n')
r = readPNG('/tmp/test.png')
# read the help for rasterImage for details
rasterImage(r,-1,-1,1,1)
# plot the points over the image
points(xvals,yvals)