Select Part of linearmask Object
Methods to subset linear mask objects.
## S3 method for class 'linearmask' subset(x, subset, LineID, droplinesbeyond = Inf, ...)
x |
linearmask object from |
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) |
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.
A linearmask object.
## 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')
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