A `skip' is defined here as a graph edge between two input lines. Many skips are
legitimate, but some `shortcut' skips are artefacts of the simple algorithm
used by asgraph to construct the graph topology. These are
better removed. These functions allow skips in a linearmask to be visualised and edited.
addedges may be used to bridge artefactual gaps in a network, or
to correct editing mistakes. The edge weight of a new edge is its Euclidean length.
showedges(mask, plt = TRUE, add = FALSE, type = c('all', 'noskips', 'skips'),
lengths = c(0,Inf), ...)replot(mask, xlim = NULL, ylim = NULL, ...)
addedges(mask, replot = TRUE, ...)
deleteedges(mask, replot = TRUE, ...)
cleanskips(mask)
showedges returns a dataframe with one row for each edge, and columns --
index of start vertex
index of finish vertex
line number of start
line number of finish
geographic coordinates of start
geographic coordinates of start
geographic coordinates of finish
geographic coordinates of finish
"weight" attribute of edge (its length in metres)
The dataframe is returned invisibly if plt = TRUE.
cleanskips returns a linearmask object.
replot returns NULL.
addedges and deleteedges invisibly returns a linear mask
object with updated graph attribute.
linearmask object with 'graph' attribute
numeric vector of minimum and maximum edge length (weight)
logical; if TRUE the edges are plotted
logical; if TRUE the edges will be added to an existing plot
character value for subset of edges to show
vector of min and max x-values for new plot
vector of min and max y-values for new plot
logical; if TRUE the plot will be re-done using replot
other arguments (see details)
showedges is a general-purpose function for displaying or
extracting edge information from the graph attribute of a linear mask.
cleanskips removes any between-line `skips' that are longer
than the shortest `skip'.
Other functions here are used to manually edit a mask graph.
replot is used to zoom in on part of a linear mask (often to inspect `skips').
The dots argument ... is passed by replot to plot.linearmask and by addedges and deleteedges to showedges (if replot = TRUE).
linearmask, getLineID