从csv文件在python中创建邻接表

Question

I am new to python. I have a CSV file showing distance matrices and would like to construct an adjacency list using the information in the CSV, but I do not have an idea how to go about this task.

CSV dataset:

I would like the distances to be the weights of the edges. Below is an example of my expected results:

AdjList = {1: [{Node2:11242, node5:1511}], 2:[{Node6:1024, Node10:985}], etc. }

Answer 1

Without loss of generality, below is a solution via numpy and collections.defaultdict .

The result is a nested dictionary, where the outer keys are row numbers and inner keys are column numbers.

The solution can be adapted to your problem and desired output. You may wish to look at pandas to extract row numbers, column names and data separately to use in the below algorithm.

from collections import defaultdict
import numpy as np

arr = np.array([[0, 134, 0, 451, 0],
                [234, 0, 4513, 0, 0],
                [0, 0, 132, 34, 0],
                [452, 562, 0, 0, 0]])

d = defaultdict(lambda: defaultdict(int))

for i in range(arr.shape[0]):
    for j in range(arr.shape[1]):
        val = arr[i, j]
        if val != 0:
            d[i+1][j+1] = val

Result

defaultdict(<function __main__.<lambda>>,
            {1: defaultdict(int, {2: 134, 4: 451}),
             2: defaultdict(int, {1: 234, 3: 4513}),
             3: defaultdict(int, {3: 132, 4: 34}),
             4: defaultdict(int, {1: 452, 2: 562})})