R/GIS: How to subset a shapefile by a lat-long bounding box?

Question

I want to subset out a shapefile (the .shp and associated files are here) into another one bounded by a set of coordinates, say between longs [80,90] and lats [20,30], and t

Answer 1

Another way:

library(raster)

s <- shapefile("/path/asia_rivers.shp")

sub <- crop(s, extent(80, 90, 20, 30))

shapefile(sub, 'cropped_rivers.shp')

Answer 2

I know this has been answered, but I think you can do exactly what you want using PBSmapping. PBSmapping has a function to clip Polysets (for polygon and lines data) so you can try:

df <- importShapefile("/path/asia_rivers.shp")
df_sub <- clipLines(df, xlim = c(80 , 90) , ylim = c(20 , 30), keepExtra = TRUE )
dfSL <- PolySet2SpatialLines( df_sub )

The keep extra allows you to keep non-standard columns when you do the clipping (I assume for attribute data).

Answer 3

You could try the following:

library(rgeos)
rivers <- readWKT("MULTILINESTRING((15 5, 1 20, 200 25), (-5 -8,-10 -8,-15 -4), (0 10,100 5,20 230))")
bbx <- readWKT("POLYGON((0 40, 20 40, 20 0, 0 0, 0 40))") 

rivers.cut <- gIntersection(rivers, bbx)

plot(rivers, col="grey")
plot(bbx, add=T, lty=2)
plot(rivers.cut, add=T, col="blue")