Extract data
On Jan 6, 2011, at 6:36 AM, Chris Mcowen wrote:
Dear List, I have a data frame called trait with roughly 800 species in, each species have 15 columns of information: Species 1 2 3 etc.. a t y h b f j u c r y u etc.. I then have another data frame called com with the composition of species in each region, there are 506 different communities: community species NA1102 a NA1102 c NA0402 b NA0402 c AT1302 a AT1302 b etc.. What i want to do is extract the information held in the first data frame for each community and save this as a new data frame.
> tapply(comm.info$species, comm.info$community, c)
$AT1302
[1] 1 2
$NA0402
[1] 2 3
$NA1102
[1] 1 3
> lapply( tapply(comm.info$species, comm.info$community, c),
function(x){ sp.info[x, ]} )
$AT1302
Species X1 X2 X3
1 a t y h
2 b f j u
$NA0402
Species X1 X2 X3
2 b f j u
3 c r y u
$NA1102
Species X1 X2 X3
1 a t y h
3 c r y u
Might have looked more compact if I had assigned the output of tapply
to an intermediate list:
comm.sp <- tapply(comm.info$species, comm.info$community, c)
lapply( comm.sp , function(x){ sp.info[x, ]} )
Resulting in : - community_NA1102 a t y h c r y u community_NA0402 b f j u c r y u Thanks in advance for any suggestions / code.
David Winsemius, MD West Hartford, CT