Unweighted Network

Loading Data

Let’s load libraries, stop and line data.

stops = read.csv("../crawler/output/stop.csv")
stops = unique(stops)
lines = read.csv("../crawler/output/linedetail.csv")

Edge Construction

Now create edges by connecting adjacent stops in each line:

newedges = list()
k = 1
for (i in 1:nrow(lines)) {
  line_name = as.character(lines$cdk_id[i])
  line_stops = strsplit(as.character(lines$stop_list[i]), ";")[[1]]
  for (j in 1:(length(line_stops)-1)){
    newedges[[k]] = c(line_stops[j], line_stops[j+1], line_name)
    k = k + 1
  }
}

Then we can convert this edge list into a matrix with columns (V1, V2, Line):

matrix_edges = matrix(data=NA, nrow=length(newedges), ncol=3)

for (i in 1:length(newedges)){
  matrix_edges[i, 1] = newedges[[i]][1]
  matrix_edges[i, 2] = newedges[[i]][2]
  matrix_edges[i, 3] = newedges[[i]][3]
}

Now we convert this matrix into a data frame with columns V1 (From), V2 (To) and Line (Edge label).

frame_edges = as.data.frame(matrix_edges, stringsAsFactors = TRUE, row.names=c("from", "to", "line"))
colnames(frame_edges) = c("V1","V2","Line")

Constructing Graph

Now that we have edges and nodes, we can construct a graph object.

library("igraph")
g = graph.data.frame(frame_edges, TRUE, stops$cdk_id)
V(g)$Latitude = stops$lat
V(g)$Longitude = stops$lon
V(g)$size = 0.5
V(g)$label = as.character(stops$name)
V(g)$labels = as.character(stops$name)
E(g)$label = as.character(frame_edges$Line)

Drawing the Map

Now create an aerial map:

library("ggmap")
## Loading required package: ggplot2
location = c(mean(stops$lon), mean(stops$lat))
map = get_map(location, maptype="watercolor", source="osm", zoom=10)
## Map from URL : http://maps.googleapis.com/maps/api/staticmap?center=41.034869,28.991441&zoom=10&size=640x640&maptype=terrain&sensor=false

Now draw the spatial map and plot nodes/edges on it:

library(popgraph)
p = ggmap(map)
p = p + geom_nodeset( aes(x=Longitude, y=Latitude, size=size, label=label), g)
p = p + geom_edgeset( aes(x=Longitude, y=Latitude, shape=label, label=label), g, color="yellow", alpha=0.3)
p + xlab("Longitude") + ylab("Latitude")
## Warning: Removed 424 rows containing missing values (geom_point).
## Warning: Removed 1453 rows containing missing values (geom_segment).