將數據列表（表示邊）加載到python中的igraph圖中

Question

我有一些列表格式的關系數據，我想導入到iGraph.Graph() 。 列表列表包含重復的邊，最終，我想為重復邊添加邊權重。 然而，目前，當我試圖將圖形邊緣添加到減去權重因子時，我無法弄清楚我做錯了什么。

我認為問題是我必須首先將所有頂點導入到圖形中，然后我可以在頂點之間添加邊緣，但似乎並非如此。

將這些邊加載到圖中我做錯了什么？

*如何修改邊緣加載過程以首先查找圖形中的邊緣，如果未找到，則添加邊緣，如果找到，則將該邊緣的權重增加1，*

數據

In [60]:    edges

Out[60]:    [['a', 'b'],
             ['a', 'b'],
             ['a', 'b'],
             ['b', 'a'],
             ['a', 'c'],
             ['c', 'a'],
             ['c', 'd'],
             ['c', 'd'],
             ['d', 'c'],
             ['d', 'c']]

IGRAPH代碼將圖形加載到圖形和錯誤中

In [61]:    # extract vertices for edges list
            vertices = []
            for line in edges:
                nodes.append(line[0])
                nodes.append(line[1])

            # find unique vertices
            uniq_vertices = set(sorted(nodes))

In [62]:    # create an empty graph
            g = igraph.Graph()

In [63]:    # add vertices to the graph
            g.add_vertices(uniq_vertices)

In [64]:    # for each line in the edges list, check to see if it's already in the graph, and if not, add it to the graph.
           for line in edges:
                 if not line in g.get_edgelist():
                     g.add_edges(edges)     

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-64-04a376c78860> in <module>()
      2 for line in edges:
      3     if not line in g.get_edgelist():
----> 4         g.add_edges(edges)

C:\Users\Curtis\Anaconda\lib\site-packages\igraph\__init__.pyc in add_edges(self, es)
    228           endpoints. Vertices are enumerated from zero.
    229         """
--> 230         return GraphBase.add_edges(self, es)
    231 
    232     def add_vertex(self, name=None, **kwds):

ValueError: no such vertex: 'a'

Answer 1

問題可能就在這里（至少這部分代碼對我來說沒有意義）：

for line in edges:
    if not line in g.get_edgelist():
        g.add_edges(edges)

在這里檢查line是否在g.get_edgelist() ，並確保它不會是因為你的edges列表包含列表，而g.get_edgelist()返回元組 。 然后添加所有邊，而不僅僅是已檢查的邊。

我附加了代碼的替代版本，似乎可以幫我完成工作。 請注意，在創建圖形時我沒有消除多個邊緣 - 我添加它們然后只需要求igraph將它們折疊成一個並將它們的權重相加：

import igraph

edges = [['a', 'b'],
         ['a', 'b'],
         ['a', 'b'],
         ['b', 'a'],
         ['a', 'c'],
         ['c', 'a'],
         ['c', 'd'],
         ['c', 'd'],
         ['d', 'c'],
         ['d', 'c']]

# collect the set of vertex names and then sort them into a list
vertices = set()
for line in edges:
    vertices.update(line)
vertices = sorted(vertices)

# create an empty graph
g = igraph.Graph()

# add vertices to the graph
g.add_vertices(vertices)

# add edges to the graph
g.add_edges(edges)

# set the weight of every edge to 1
g.es["weight"] = 1

# collapse multiple edges and sum their weights
g.simplify(combine_edges={"weight": "sum"})