title: plotting points on shapefile
body: <p>I'm trying to plot some points on a a map generated from a shapefile, but can't understand why they are not being plotted correctly on the map.</p>
  
  <pre><code>library(rgeos)
  library(maptools)
  library(plyr)
  library(ggplot2)
  library(dplyr)
  library(sp)
  library(rgdal)
  
  
  # load shapefile 
  
  np_dist &lt;- readShapeSpatial("~/world/coastlines_z1.shp")  #http://data.openstreetmapdata.com/coastlines-generalized-3857.zip
  plot(np_dist)  
  
  
  ##### add points
  
  points &lt;- data.frame(lat = c(55.4, 35.8, 36.4), lon = c(-5.5, -5.6, -35.8))
  points &lt;- SpatialPoints(points)
  
  plot(points, add= TRUE , col = 'red')
  </code></pre>