What the following error means: Topology Exception: An unexpanded intersection between LINESTRING was detected

Question

I am trying to consolidate a form file that I loaded into R using rgdal, but I get the following error:

"Error: TopologyException: found non-noded intersection between LINESTRING (34.7279 1.59723, 34.7278 1.59729) and LINESTRING (34.7278 1.59723, 34.7278 1.59729) at 34.727793021883102 1.5972887049072426" 

I am using a form file for the continent of Africa with maplibrary.org. It is available from my Dropbox here: https://www.dropbox.com/s/etqdw3nky52czv4/Africa%20map.zip

I am using the following code:

 library(rgdal) library(ggplot2) africa = readOGR("Africa_SHP", layer = "Africa") africa.map = fortify(africa, region="COUNTRY") 

And I get the error that I mentioned earlier. I believe that R has some problems with the polygon - is there a way around this?

Answer 1

As you can see from the comments, mdsumner and agstudy were able to answer why this is happening, although agstudy was not able to recreate it with an accessible dataset. I found a job around this problem.

 library(rgdal) library(rgeos) library(ggplot2) #LOADING IN DATA africa = readOGR("directory", layer="filename") #FIXING THE NON-NODED INTERSECTS# africa = gBuffer(africa, width=0, byid=TRUE) africa.map = fortify(africa, region="ID")