Getting the max value of attributes from a list of objects

There's a built-in to help with this case.

import operator

print(max(path.nodes, key=operator.attrgetter('y')))

Alternatively:

print(max(path.nodes, key=lambda item: item.y))

Edit: But Mark Byers' answer is most Pythonic.

print(max(node.y for node in path.nodes))

To get just the maximum value and not the entire object you can use a generator expression:

print(max(node.y for node in path.nodes))