subset.linearmask: Select Part of linearmask Object

Description

Methods to subset linear mask objects.

Usage

# S3 method for linearmask
subset(x, subset, LineID, droplinesbeyond = Inf, ...)

Value

A linearmask object.

Arguments

x: linearmask object from read.linearmask
subset: numeric or logical vector to select rows of mask
LineID: vector of identifiers for lines to retain
droplinesbeyond: logical; distance criterion for dropping lines (m)
...: other arguments (not used)

Details

Specify only one of `subset' and `LineID'.

If the input object has a `graph' attribute then a new graph will be included in the output.

subset.linearmask leaves the underlying SpatialLinesDataFrame intact unless either (i) LineID is specified, or (ii) a finite value is provided for droplinesbeyond. droplinesbeyond retains lines that have at least one point within the specified distance of at least one mask point, after subsetting.

Examples

Run this code



## rbind two linear masks,
x <- seq(0, 4*pi, length = 200)
xy <- data.frame(x = x*100, y = sin(x)*300)
xy2 <- data.frame(x = x*100, y = cos(x)*300)
test <- read.linearmask(data = xy, spacing = 10)
test2 <- read.linearmask(data = xy2, spacing = 10)
test3 <- rbind(test, test2)
table(covariates(test3)$LineID)

## then retrieve one... 
test4 <- subset(test3, LineID = '1.1')

## ... or the other
test5 <- subset(test3, LineID = '2.1')