LR_Incidence_Matrix.py

'''
Created on Dec 2, 2014

@author: sudatta0993
'''
#This program evaluates the shortest-path link-route incidence matrix for a given network and stores it in a .csv file
#Algorithm: Generate shortest path between all nodes in the network. For each path, iterate through all links and check if link falls within shortest path. If it does, then add 1. Else, add 0.
#Inputs: .csv file with info on all links in the network i.e. linkID, fromNodeID, toNodeID 

#Imports
import networkx as nx
import numpy as np
import csv
import sys

#Importing data from .csv file (columns linkID, fromNodeID, toNodeID respectively), file link specified as a command line argument
data = np.genfromtxt(sys.argv[1], delimiter=',', skiprows=1, usecols=(1,26,27))

#Defining the network using a graph
G=nx.Graph()
for i in range(len(data)):
    G.add_node(data[i][1])
    G.add_node(data[i][2])
    G.add_edge(data[i][1],data[i][2],{'ID':data[i][0]})
ID=nx.get_edge_attributes(G,'ID')

#Calculating link-route incidence matrix
a = []
for i in range(len(data)):
    for j in range(len(data)):
        for k in range(len(data)):
            try:
                if (data[k][1] in list(nx.shortest_path(G,data[i][1], data[j][2]))) and (data[k][2] in list(nx.shortest_path(G,data[i][1], data[j][2]))):
                    a.append([1])
                else:
                    a.append([0])
            except (nx.NetworkXNoPath,nx.NetworkXError):
                a.append([0])
a=np.array(a)
b=np.zeros((G.number_of_edges()*G.number_of_edges(),G.number_of_edges()))
for i in range(G.number_of_edges()*G.number_of_edges()):
    for j in range(G.number_of_edges()):
        b[i][j]=a[i*G.number_of_edges()+j]

#Storing in .csv file
with open('C:\Users\Sudatta\Downloads\Incidence_matrix.csv','wb') as f:
    writer = csv.writer(f)
    for i in range(len(b)):
        writer.writerow(b[i])