#Simulations using the maps package:
library(maps)

q <- map("county", "ca")

#What does object q contain?  See the names first:
names(q)

#We want the range of the longitude and latitude:
q$range[1]
q$range[2]
q$range[3]
q$range[4]

#Randomly select 200 points from the box defined by the longitude and latitude ranges:
xx <- runif(200,q$range[1], q$range[2])
yy <- runif(200,q$range[3], q$range[4])

#Find the state in which each point falls:
in.what.state <- map.where(database="state", xx, yy) 

#Find the points that fall in California:
in.this.state <- which(in.what.state=="california")

#Create a data frame of the California points:
locations <- as.data.frame(cbind(xx,yy))
loc <- locations[in.this.state,]

#Plot the points on the map:
map("county", "ca")
points(loc)