cartography (version 1.3.0)

getLinkLayer: Create a SpatialLinesDataFrame from a Data Frame of Links.

Description

Create a SpatialLinesDataFrame from a data frame of links.

Usage

getLinkLayer(spdf, spdf2 = NULL, df, spdfid = NULL, spdf2id = NULL, dfids = NULL, dfide = NULL)

Arguments

spdf

a SpatialPointsDataFrame or a SpatialPolygonsDataFrame; layer used to get starting points of links. If spdf2 is NULL, spdf is also used to get ending points. If spdf is a SpatialPolygonsDataFrame, links start (or end) at centroids.

spdf2

a SpatialPointsDataFrame or a SpatialPolygonsDataFrame; layer used to get ending points of links. If spdf2 is a SpatialPolygonsDataFrame, links start (or end) at centroids. (optional)

df

a data frame that contains identifiers of starting and ending points.

spdfid

identifier field in spdf, default to the first column of the spdf data frame. (optional)

spdf2id

identifier field in spdf2, default to the first column of the spdf2 data frame. (optional)

dfids

identifier field of starting points of links in df, default to the first column of df. (optional)

dfide

identifier field of ending points of links in df, default to the second column of df. (optional)

Value

A SpatialLinesDataFrame is returned, its data frame contains two fields (dfids and dfide).

See Also

gradLinkLayer, propLinkLayer

Examples

data("nuts2006")
# Create a link layer
head(twincities)
# Select links from Ireland (IE)
twincitiesIE <- twincities[substr(twincities$i,1,2)=="IE", ]
twincities.spdf <- getLinkLayer(spdf = nuts2.spdf, df = twincitiesIE[,1:2])
# Plot the links
plot(nuts2.spdf, col = "#6C6870")
plot(twincities.spdf, col = "#F78194", add = TRUE)