Get No. of Google Search Hits with R and XML

UPDATE: Thanks to Max Ghenis for updating my R-script which I wrote a while back - the below R-script can now be used again for pulling the number of hits from Google-Search.

GoogleHits <- function(input)
   {
    require(XML)
    require(RCurl)
    url <- paste("https://www.google.com/search?q=\"",
                 input, "\"", sep = "")
 
    CAINFO = paste(system.file(package="RCurl"), "/CurlSSL/ca-bundle.crt", sep = "")
    script <- getURL(url, followlocation = TRUE, cainfo = CAINFO)
    doc <- htmlParse(script)
    res <- xpathSApply(doc, '//*/div[@id="resultStats"]', xmlValue)
    cat(paste("\nYour Search URL:\n", url, "\n", sep = ""))
    cat("\nNo. of Hits:\n")
    return(as.integer(gsub("[^0-9]", "", res)))
   }
 
# Example:
GoogleHits("R%Statistical%Software")

p.s.: If you try to do this in a robot fashion, like:

lapply(list_of_search_terms, GoogleHits)

google will block you after about the 300th recursion!

R GIS: Polygon Intersection with gIntersection{rgeos}

A short tutorial on doing intersections in R GIS. gIntersection{rgeos} will pick the polygons of the first submitted polygon contained within the second poylgon - this is done without cutting the polygon's edges which cross the clip source polygon. For the function that I use to download the example data, url_shp_to_spdf() please see HERE.

library(rgeos)
library(dismo)

URLs <- c("http://gis.tirol.gv.at/ogd/umwelt/wasser/wis_gew_pl.zip",               # all water bodies in Tyrol
          "http://gis.tirol.gv.at/ogd/umwelt/wasser/wis_tseepeicher_pl.zip")       # only artificial..

y <- lapply(URLs, url_shp_to_spdf)
z <- unlist(unlist(y))
a <- getData('GADM', country = "AT", level = 2)

b <- a[a$NAME_2=="Innsbruck Land", ]                                               # political district's boundaries
c <- spTransform(b, z[[1]]@proj4string)                                            # (a ring polygon)    
z1_c <- gIntersection(z[[1]], c, byid = TRUE)                                      
z2_c <- gIntersection(z[[2]], c, byid = TRUE)

plot(c)
plot(z1_c, lwd = 5, border = "red", add = T)
plot(z2_c, lwd = 5, border = "green", add = T)
plot(z[[1]], border = "blue", add = T)              # I plot this on top, so it will be easier to identify
plot(z[[2]], border = "brown", add = T)

Batch Downloading Zipped Shapefiles with R

Here's a function I use to download multiple zipped shapefiles from url and load them to the workspace:

URLs <- c("http://gis.tirol.gv.at/ogd/umwelt/wasser/wis_gew_pl.zip",
          "http://gis.tirol.gv.at/ogd/umwelt/wasser/wis_tseepeicher_pl.zip")

url_shp_to_spdf <- function(URL) {

  require(rgdal)

  wd <- getwd()
  td <- tempdir()
  setwd(td)

  temp <- tempfile(fileext = ".zip")
  download.file(URL, temp)
  unzip(temp)

  shp <- dir(tempdir(), "*.shp$")
  lyr <- sub(".shp$", "", shp)
  y <- lapply(X = lyr, FUN = function(x) readOGR(dsn=shp, layer=lyr))
  names(y) <- lyr

  unlink(dir(td))
  setwd(wd)
  return(y)
  }

y <- lapply(URLs, url_shp_to_spdf)
z <- unlist(unlist(y))

# finally use it:
plot(z[[1]])