Thank you so much. It is solved. My mistake was that I wrote 'conda deactivate' in the home directory instead of the code's directory. But now it shows another error. When I run my code, it shows this error: Traceback (most recent call last): File "GirvanIgraph.py", line 18, in <module> igraph_graph = pyintergraph.gt2igraph(graph_tool_graph, labelname="node_label") File "/home/narges/.local/lib/python3.6/site-packages/pyintergraph/funcs.py", line 17, in gt2igraph return G.to_igraph() File "/home/narges/.local/lib/python3.6/site-packages/pyintergraph/Graph.py", line 289, in to_igraph iG.vs[i].update_attributes(name=self.node_labels[node], **attr) TypeError: update_attributes() got multiple values for keyword argument 'name' -- Sent from: http://main-discussion-list-for-the-graph-tool-project.982480.n3.nabble.com/