Floyd Warshall for PySAL Networks

gistfile1.py

import pysal as ps

#Lots of reload for dev.
try:
    reload(network)
except:
    import network
    
try:
    reload(analysis)
except:
    import analysis
    

try:
    reload(util)
except:
    import util

from collections import defaultdict

ntw = network.Network(ps.examples.get_path('geodanet/streets.shp'))

dist = defaultdict(lambda : defaultdict(lambda : np.inf)) #defaultdict requires callable args
pred = defaultdict(dict)

#populate initial predecessor and distance dictionaries
for node,neighbors in ntw.adjacencylist.iteritems():
    for neighbor in neighbors:
        if (node,neighbor) in ntw.edge_lengths.keys():
            dist[node][neighbor] = ntw.edge_lengths.get((node,neighbor))
            pred[neighbor].update({node : [node]})
        elif (neighbor, node) in ntw.edge_lengths.keys():
            dist[node][neighbor] = ntw.edge_lengths.get((neighbor,node))
            pred[neighbor].update({node : [node]})
    dist[node][node] = 0
    pred[node][node] = np.NaN

#update precedence and distance using intermediate paths
for inter in ntw.node_list:
    for start in ntw.node_list:
        for dest in ntw.node_list:
            try:
                if dist[start][dest] > dist[start][inter] + dist[inter][dest]:
                    dist[start][dest] = dist[start][inter] + dist[inter][dest]
                    pred[start][dest] = pred[start][inter] + pred[inter][dest]
            except KeyError:
                pass

I've noticed this doesn't format the predecessor list in the same way the current network.alldistances results are formatted. It makes comparison more difficult. but, the distance lists are the same for all observations, so hopefully the predecessor list isn't screwed up. Manually checking a few and I don't see problems.