Select Part of linearmask Object

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Description

Methods to subset linear mask objects.

Usage

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

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.

Value

A linearmask object.

See Also

read.linearmask, linearmask

Examples

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## 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')