Is there an annotated river dataset available?
On Jan 8, 2010, at 2:29 PM, Karl Ove Hufthammer wrote:
On Fri, 8 Jan 2010 13:25:24 +0100 Hans-J?rg Bibiko <bibiko at eva.mpg.de> wrote:
Thanks for the hint! The absolute length can make sense of course but if I need also the largest rivers of a smaller island then this fails or it's much more tricky to handle/select.
Not really. You could for example use 'ddply' from the 'plyr' package to get the names/IDs of the longest rivers for each country/island/... Then select the rivers with these names/IDs.
Yes, but my dataset has no names or IDs and furthermore I've just encountered that my rivers are split into line segments :( The only chance would be to combine these segments and select those rivers/lines which are inside of country/island polygons. Thanks, --Hans