convert adjacency matrix to adjacency list python code example

Example 1: how to convert adjacency matrix to adjacency list

#Python:
def convert_to_adjacency(matrix):
    start = 0
    res = []
    lst = []
    n = len(matrix)

    for i in range(n):
        res.append(lst*n)
    while start < n:
        y = matrix[start]
        for i in range(len(y)):
            if y[i] == 1:
                res[start].append(i)
        start += 1
    return res
matrix = [[0, 1, 1, 1, 0, 1, 1, 0, 0],
          [1, 0, 0, 1, 0, 0, 1, 1, 0],
          [1, 0, 0, 1, 0, 0, 0, 0, 0],
          [1, 1, 1, 0, 1, 0, 0, 0, 0],
          [0, 0, 0, 1, 0, 1, 0, 0, 1],
          [1, 0, 0, 0, 1, 0, 0, 0, 1],
          [1, 1, 0, 0, 0, 0, 0, 0, 0],
          [0, 1, 0, 0, 0, 0, 0, 0, 0],
          [0, 0, 0, 0, 1, 1, 0, 0, 0]]
print(convert_to_adjacency(matrix))

Example 2: how to convert adjacency list to adjacency matrix

#Python:
def convert_to_matrix(graph):
    matrix = []
    for i in range(len(graph)): 
        matrix.append([0]*len(graph))
        for j in graph[i]:
            matrix[i][j] = 1
    return matrix
#the lst shows in a form of each index(each inner list) as a form of vertex,
#and each element in the inner list as the vertices that each vertex connected to.
lst = [[1,2,3,5,6],[0,3,6,7],[0,3],[0,1,2,4],[3,5,8],[0,4,8],[0,1],[1],[4,5]]
print(convert_to_matrix(lst))