NetworkX: https://networkx.github.io/

The tutorial is well-written, and I only summarize my understanding below:

Element
    Graph (Graph, DiGraph), Node, Edge

Graph generation
    1. adding node/edge: G.add_node(), G.add_nodes_from(), G.add_edge(), G.add_edges_form(), G.add_weighted_edge(),
                                           G.add_weighted_edges_from()
    2. pre-defined graphes

Graph property access
    1. node/edge: G.nodes(), G.number_of_nodes(), G.edges(), G.number_of_edges()
    2. connection:
    3.