NetworkX largest component no longer working?

The networkx-1.9 documentation is here http://networkx.github.io/documentation/networkx-1.9/reference/generated/networkx.algorithms.components.connected.connected_components.html#networkx.algorithms.components.connected.connected_components

The interface was changed to return a generator (as you figured out). The example in the documentation shows how to do what you ask.

Generate a sorted list of connected components, largest first.

>> G = nx.path_graph(4)
>>> G.add_path([10, 11, 12])
>>> sorted(nx.connected_components(G), key = len, reverse=True)
[[0, 1, 2, 3], [10, 11, 12]]

or

>>> sorted(nx.connected_component_subgraphs(G), key = len, reverse=True)

As for version 2.4: nx.connected_component_subgraphs(G) is removed.

Instead to get the same result use:

connected_subgraphs = [G.subgraph(cc) for cc in nx.connected_components(G)]

And to get the giant component:

Gcc = max(nx.connected_components(G), key=len)
giantC = G.subgraph(Gcc)