This is the graph that represents a railroad in a little town. All of the tracks are 'one-way.' That is, a route from A to B does not imply the existence of a route from B to A. In fact, even if both of these routes do happen to exist, they are distinct and are not necessarily the same distance.
For example, in the graph below, there is a route from A to B, but there is no route from B to A. There is also a route from C to D and vice versa. The number next to line indicate the distance between stations.
In order for this program to work it needs data which is located at little-mrt/lib/data.yml. little-mrt/lib/data.yml contains stations and adjacency matrix. A adjacency must has from and to station and distance between the stations.
Add this to your Gemfile
gem 'little-mrt', git: 'git@github.com:ungsophy/little-mrt.git'
A simple example:
require 'little-mrt'
graph = LittleMRT::Graph.new
paths = graph.search('A-B-C')
paths.first.distance # 9
paths.first.to_s # 'A-B-C'It looks like LittleMRT::Graph#search returns an array of paths. Yes you're right, but it's more than just a regular array. It returns LittleMRT::Paths object that wrapped array of paths and added a couple more useful filter methods into it. You will see it next.
paths = graph.search('A-C') # It retuns all possible paths from A to C.
# A-B-C, A-D-C, A-D-E-B-C and A-E-B-C
paths.min_distance # It returns LittleMRT::Path
# that has the shortest distance which is A-B-C.
paths = graph.search('C-C') # It retuns all possible paths from C to C.
# C-D-C, C-D-E-B-C and C-E-B-C
paths.max_stop(3) # It returns a new LittleMRT::Paths object
# that have paths that have no more than 3 stops.
# C-D-C and C-E-B-CThis program requires Ruby 1.9+
To run test:
$ cd little-mrt
$ bundle install
$ rake
See LICENSE file.