dggridR (version 2.0.4)

dgcellstogrid: Return boundary coordinates for specified cells

Description

Returns the coordinates constituting the boundary of a specified set of cells. Duplicates are eliminated to reduce processing and storage requirements.

Usage

dgcellstogrid(dggs, cells, frame = TRUE, wrapcells = TRUE, savegrid = NA)

Arguments

dggs

A dggs object from dgconstruct()

cells

The cells to get the boundaries of

frame

If TRUE, return a data frame suitable for ggplot plotting. If FALSE, return an OGR poly object

wrapcells

Cells which cross -180/180 degrees can present difficulties for plotting. Setting this TRUE will result in cells with components in both hemispheres to be mapped entirely to positive degrees (the Eastern hemisphere). As a result, such cells will have components in the range [180,360). Only used when frame=TRUE.

savegrid

If savegrid is set to a file path, then a shapefile containing the grid is written to that path and the filename is returned. No other manipulations are done. Default: NA (do not save grid, return it)

Value

Returns a data frame or OGR poly object, as specified by frame. If !is.na(savegrid), returns a filename.

Examples

# NOT RUN {
library(dggridR)
data(dgquakes)

#Construct a grid with cells about ~1000 miles wide
dggs          <- dgconstruct(spacing=1000,metric=FALSE) 
dgquakes$cell <- dgtransform(dggs,dgquakes$lat,dgquakes$lon)

#Get grid cells for the earthquakes identified
grid          <- dgcellstogrid(dggs, dgquakes$cell, frame=TRUE)
# }