[graph-tool] Unexpected property map to/from gml behaviour

17 Jul 2014


      In the following, I noticed the data type of the property map changes.  Any
ideas what is going on?
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graph_tool.all.__version__
    '2.2.31 (commit 245d1e2c, Thu Mar 27 11:28:39 2014 +0100)
# having already built my graph
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graph.ep
{'weight': <PropertyMap object with key type 'Edge' and value type
'int32_t', for Graph 0x7f93019b8b90, at 0x7f930058c850>}
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graph.ep['weight'].a
    PropertyArray([28, 18, 32, ...,  7,  8,  8], dtype=int32)
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graph.save(graph_file_name)
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graph2 = Graph()
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graph2.load(graph_file_name)
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graph2.ep
    {'weight': <PropertyMap object with key type 'Edge' and value type
'double', for Graph 0x7f93001b7b10, at 0x7f92fc00b190>}
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graph2.ep['weight'].a
    PropertyArray([ 28.,   3.,  18., ...,  11.,   6.,  55.])
Then it gets weirder...
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graph.ep['ONE_WAY'] = graph.new_edge_property('string')
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for edge in graph.edges():
...     graph.ep['ONE_WAY'][edge] = 'TEST!'
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graph.ep
{'ONE_WAY': <PropertyMap object with key type 'Edge' and value type
'string', for Graph 0x7f93019b8b90, at 0x7f9327c0dc10>,
 'weight': <PropertyMap object with key type 'Edge' and value type
'int32_t', for Graph 0x7f93019b8b90, at 0x7f930058c850>}
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graph.ep['ONE_WAY'][edge]
    'TEST!'
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graph.save(graph_file_name)
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graph2 = Graph()
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graph2.load(graph_file_name)
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graph2.ep
    {}
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graph.num_edges(),graph.num_vertices()
    (78147, 29870)
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graph2.num_edges(),graph2.num_vertices()
    (1, 29870)