我正在嘗試使用networkX（以gexf格式使用）自定義圖形。但是我無法設(shè)置節(jié)點(diǎn)的形狀。在這里使用示例import sysimport urllib2import networkx as nxdata = urllib2.urlopen('http://gexf.net/data/viz.gexf')G = nx.read_gexf(data)print G.node['a']G.node['a']['viz']['position']['x']=10G.node['a']['viz']['position']['y']=20# now my addition G.node['a']["viz"]['shape'] = 'disc'print G.node['a'] this seems to work但我不能寫文件nx.write_gexf(G,sys.stdout)錯(cuò)誤是：# AttributeError: 'str' object has no attribute 'get'我想念什么嗎？