Why you gotta be all lazy?

:-)

#14

What is the point of using a class if you pass in the graph as a parameter anyways?

As a starting-point: I've hacked py-dag to barely work for Python 3 in saxifrage/caac-map@962610b.

Really enjoying playing with this library to learn some Python.

Here's a graph that's used a lot in the tests:

dag.from_dict({'a': ['b', 'c'],
               'b': ['d'],
               'c': ['d'],
               'd': []})

For this graph the shortest path from a to d is a => b = d

Here's how this algo can be implemented:

def iter_flatten(iterable):
  it = iter(iterable)
  for e in it:
    if isinstance(e, (list, tuple)):
      for f in iter_flatten(e):
        yield f
    else:
      yield e

def shortest_path(self, start, end, graph=None):
    if graph is None:
        graph = self.graph
    dist = {start: [start]}
    q = deque([start])
    while len(q):
        at = q.popleft()
        for next in graph[at]:
            if next not in dist:
                dist[next] = [dist[at], next]
                q.append(next)
    a = dist.get(end)
    return [i for i in iter_flatten(a)]

The iter_flatten is a hack and could probably be improved a bunch, but it works!

Let me know if you'd be open to adding this and I can send a pull request with some tests.

On 19 February 2017, Python 3 will be 3,000 days old! We are interested to see if we can get at least 50% of the Top 5,000 PyPI packages to compatible with Python 3 by that date. We are really close and given that this package is in the PyPI Top 5,000, we seek your assistance in pushing us over that threshold.

So, if this package already supports Python 3 then please consider adding an appropriate trove classifier "Programming Language :: Python :: 3" to this package's PyPI page so that tools can automaticly determine its Python 3 compatibility.

Right now the method for doing a topological sort is DAG._topological_sort, which follows the python convention for labelling "private" methods. I believe this is actually a first class feature of this library, and should follow the convention for "public" methods (so it would be DAG.topological_sort).