This piece gets some summary statistics on spatial line data frame lengths within spatial polygon data frames in R

LineLengthsPolys.R

library(rgeos);library( rgdal)
polys <- readOGR('.','polys')
lines <- readOGR('.','lines')
if (proj4string(polys) == proj4string(lines){ 
  plot(polys); plot(lines, add=T, color='Blue')
  lines$LENGTHKM <- SpatialLinesLengths(lines)*0.001 # assumes lines are in projection using meters
  line.sum <- over(polys, lines[6], fn=sum)
  line.mean <- over(polys, lines[6], fn=mean)
  line.min <- over(polys, lines[6], fn=min)
  line.max <- over(polys, lines[6], fn=max)
}  
if (proj4string(polys) != proj4string(lines){
  polys <- spTransform(polys, CRS(proj4string(lines))
  plot(polys); plot(lines, add=T, color='Blue')
  lines$LENGTHKM <- SpatialLinesLengths(lines)*0.001 # assumes lines are in projection using meters
  line.sum <- over(polys, lines[6], fn=sum)
  line.mean <- over(polys, lines[6], fn=mean)
  line.min <- over(polys, lines[6], fn=min)
  line.max <- over(polys, lines[6], fn=max)
}  
results <-data.frame(line.sum, line.mean, line.min, line.max)
names(results) <- c('LineSum', 'LineMean', 'LineMin','LineMax')
polys@data <- data.frame(polys@data, results)
head(polys@data)