spThinner: Spatially thin a data frame of eBird records
In eliotmiller/ebirdr: Manipulate eBird data

Description Usage Arguments Details Value References Examples

Single data frame spatial thinning within an R session.

1 2	spThinner(ebird.data, xxx, yyy, latitude, longitude, xlim = c(NA, NA), ylim = c(NA, NA), nx, ny, jitter = FALSE, size, replace = FALSE)

`ebird.data`	Dataframe of eBird records.
`xxx`	Either E-W coordinates, or the word "extent". If extent is desired, make sure to specify for both xxx & yyy. Function will not handle mixture gracefully.
`yyy`	Either N-S coordinates, or the word "extent". If extent is desired, make sure to specify for both xxx & yyy. Function will not handle mixture gracefully.
`latitude`	The name of the latitude column in the files.
`longitude`	The name of the longitude column in the files.
`xlim`	Together xlim and ylim define a bounding box within which lookup occurs. I.e. all (xxx, yyy) pairs outside of this box are ignored.
`ylim`	Together xlim and ylim define a bounding box within which lookup occurs. I.e. all (xxx, yyy) pairs outside of this box are ignored.
`nx`	Number of grid cells in x direction.
`ny`	Number of grid cells in y direction.
`jitter`	Defaults to FALSE. Set to TRUE to randomize grid location.
`size`	Maximum number of points per cell to sample
`replace`	Defaults to FALSE. Set to TRUE to sample with replacement.

This applies sample.grid.cell() to single eBird data frame.

A spatially thinned data frame.

Team eBird.

data(ex)
plot(ex$LONGITUDE~ex$LATITUDE, col="blue", pch=20, cex=2)
thinned <- spThinner(ebird.data=ex, xxx="extent", yyy="extent",
  latitude="LATITUDE", longitude="LONGITUDE", nx=2, ny=2, size=3)
points(y=thinned$LONGITUDE, x=thinned$LATITUDE, col="red", pch=20, cex=1)
#the blue points are the original data, the red points are the accepted points
#after spatial thinning.