[igraph] input shapefile to build graph-using R

[Hao Wang]

When using igraph to do network analysis- computing closeness for road network, I confront these problems. I am trying to input shapefile data(line and vertex), the R code is as follows:

library(igraph)

library(maptools)

pl <- readShapeLines("H:/data/Beijing_NatrualRoads.shp",proj4string=CRS("+proj=Mercator_Auxiliary_Sphere +datum=WGS84"))

pt <- readShapePoints("H:/data/Beijing_NatrualRoads_ND_Junctions.shp",proj4string=CRS("+proj=Mercator_Auxiliary_Sphere +datum=WGS84"))

Then errors occurs when trying to build graph using function "graph.data.frame":

> g <- graph.data.frame(pl, directed=FALSE, vertices=pt)

Error in graph.data.frame(pl, directed = FALSE, vertices = pt) : 

  Duplicate vertex names

Warning:

In graph.data.frame(pl, directed = FALSE, vertices = pt) :

  In `d' `NA' elements were replaced with string "NA"‍

Could anyone help me to solve these problems, thank you very much.

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Hao Wang

Institute of Geomatics,

Department of Civil Engineering, 

Tsinghua University,

Haidian District, Beijing 100084, P.R. China