161 lines
4.9 KiB
Markdown
161 lines
4.9 KiB
Markdown
---
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title: "Dijkstra's Shortest Path"
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description: "Dijkstra's shortest path."
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navigation: false
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date: "2021-03-02 02:31:20"
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img: "/img/algorithms/dijkstras-shortest-path.png"
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tags:
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- Algorithm
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---
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Implementation of the shortest path algorithm, invented by Dijkstra.
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```python
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#!/usr/bin/python
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import os
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import time
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# List of all the cities
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cities = [
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"Ab'Dendriel",
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"Ankrahmun",
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"Carlin",
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"Darashia",
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"Edron",
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"Liberty Bay",
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"Port Hope",
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"Roshamuul",
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"Oramond",
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"Svargrond",
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"Thais",
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"Venore",
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"Yalahar",
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"Krailos",
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"Issavi",
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"Cormaya",
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]
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# Possible boat fares
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fares = [
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[None, None, 80, None, 70, None, None, None, None, None, 130, 90, 160, None, None, None], # Ab'Dendriel
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[None, None, None, 100, 160, 90, 80, None, None, None, None, 150, 230, None, None, None], # Ankrahmun
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[ 80, None, None, None, 110, None, None, None, None, 110, 110, 130, 185, None, None, None], # Carlin
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[None, 100, None, None, None, 200, 180, None, None, None, None, 60, 210, 110, 130, None], # Darashia
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[ 70, 160, 110, None, None, 170, 150, None, None, None, 160, 40, None, 100, None, 20], # Edron
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[None, 90, None, 200, 170, None, 50, None, None, None, 180, 180, 275, None, None, None], # Liberty Bay
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[None, 110, None, 180, 150, 50, None, None, None, None, 160, 160, 260, None, None, None], # Port Hope
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[None, None, None, None, None, None, None, None, None, None, 210, None, None, None, None, None], # Roshamuul
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[None, None, None, None, 110, None, 200, None, None, None, 150, 130, None, 60, 120, None], # Oramond
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[None, None, 110, None, None, None, None, None, None, None, 180, 150, None, None, None, None], # Svargrond
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[ 130, None, 110, None, 160, 180, 160, 210, 150, 180, None, 170, 200, None, None, None], # Thais
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[ 90, 150, 130, 60, 40, 180, 160, None, None, 150, 170, None, 185, 110, 130, None], # Venore
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[ 160, 230, 185, 210, None, 275, 260, None, None, None, 200, 185, None, None, None, None], # Yalahar
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[None, None, None, 110, 100, None, None, None, 60, None, None, 110, None, None, 70, None], # Krailos
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[None, None, None, 80, None, None, None, None, 100, None, None, 80, None, 80, None, None], # Issavi
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[None, None, None, None, 20, None, None, None, None, None, None, None, None, None, None, None], # Cormaya
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]
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# Say phrase
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def say(string):
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time.sleep(0.2)
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os.system('xdotool key Return')
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os.system('xdotool keydown Alt')
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os.system('xdotool type "' + string + '"')
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os.system('xdotool keyup Alt')
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os.system('xdotool key Return')
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# Say fare
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def typeFare(city):
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say("hi")
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time.sleep(1.0)
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say(city)
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say("yes")
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def dijkstraShortestPath(sourceVertex):
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explored = []
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unexplored = []
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# Setup vertices
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for i, fare in enumerate(fares[sourceVertex]):
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unexplored.append([i, None, None])
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# Set the source vertex distance to 0
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if i == sourceVertex:
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unexplored[-1][1] = 0
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while len(unexplored) > 0:
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# Select the closest vertex
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closest = None
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distance = None
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for i, vertex in enumerate(unexplored):
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if (distance == None and vertex[1] != None) or \
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(vertex[1] != None and vertex[1] < distance):
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closest = i
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distance = vertex[1]
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# Move the closest vertex to explored
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explored.append(unexplored.pop(closest))
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ID = explored[-1][0]
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# Explore this vertex
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for i, vertex in enumerate(unexplored):
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# Is linked
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if fares[ID][vertex[0]] != None:
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# If it hasnt been set before
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if vertex[1] == None:
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vertex[1] = fares[ID][vertex[0]] + explored[-1][1]
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vertex[2] = ID
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# Or is cheaper
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elif vertex[1] > fares[ID][vertex[0]] + explored[-1][1]:
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vertex[1] = fares[ID][vertex[0]] + explored[-1][1]
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vertex[2] = ID
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return explored
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def dijkstraTraversePath(sourceVertex, targetVertex, explored):
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find = targetVertex
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path = [targetVertex]
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while find != sourceVertex:
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for i, vertex in enumerate(explored):
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if vertex[0] == find:
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find = vertex[2]
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path.append(vertex[2])
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break
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path.pop()
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path.reverse()
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return path
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def main():
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locations = '\n'.join(cities)
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current = os.popen('echo "' + locations + '" | rofi -dmenu -i -p "Where are you now?"').read().rstrip()
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destination = os.popen('echo "' + locations + '" | rofi -dmenu -i -p "Where are you going?"').read().rstrip()
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if not current or not destination: return
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currentIndex = cities.index(current)
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destinationIndex = cities.index(destination)
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# If a direct route is possible
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if fares[currentIndex][destinationIndex] != None:
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typeFare(destination)
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return
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# Calculate possible non-direct route
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data = dijkstraShortestPath(currentIndex)
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path = dijkstraTraversePath(currentIndex, destinationIndex, data)
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for index in path:
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typeFare(cities[index])
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if __name__ == "__main__":
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main()
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```
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Source:<br>
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[Dijkstra Algorithm - Example (YouTube)](https://www.youtube.com/watch?v=JcN_nq1EAr4){ target=_blank }
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