[igraph] Python's Graph.write_x producing empty files

[Jeff Alstott]

In [1]: from igraph import Graph

In [2]: g = Graph(1)

In [5]: g.add_vertices(2)

In [7]: g.add_edges([(0,1), (1,2)])

In [8]: print(g)

IGRAPH U--- 3 2 --

+ edges:

0--1 1--2

In [9]: g.write_pajek('test')

In [11]: g.write_graphml('test')

In [12]: g.write('test.net')

In [13]: g.write('test.net', format='net')

In [14]: g.write('test.net', format='pickle')

In [15]: g.save('test.net')

In [16]: f = open('test.net', 'w')

In [17]: g.write_pajek(f)

All of these produce empty files, instead of something with information on the graph g. What am I doing wrong?

Thanks!