python - Performing a breadth first search using a given class -

using following (very badly written) class:

class graph:     def __init__(self, graph_string):     self.graph_string = []     graph_string = graph_string.splitlines()     in graph_string:         = (i.split())         self.graph_string.append(i)     directed_helper = self.graph_string[0]     directed_score = directed_helper[0]     weighted_helper = self.graph_string[0]     weighted_score = weighted_helper[1]     self.weighted = weighted_score     self.directed = directed_score     self.graph_string.pop(0)     if self.directed == ("d"):         self.directed = true     elif self.directed == ("u"):         self.directed = false     if self.weighted == ("w"):         self.weighted = true     elif self.weighted != ("w"):         self.weighted = false     if self.weighted == false:         self.edge_number = graph_string[0]         self.edge_number = list(self.edge_number)         self.edge_number = self.edge_number[2]         self.edge_number = int(self.edge_number)         self.adjacency_list = [[] _ in range(self.edge_number)]       elif self.weighted == true:         self.edge_number = graph_string[0]         self.edge_number = list(self.edge_number)         self.edge_number = self.edge_number[4]         self.edge_number = int(self.edge_number)         self.adjacency_list = [[] _ in range(self.edge_number)]                  if self.weighted == false:         if self.directed == true:             s in self.graph_string:                 first_element = s[0]                 first_element = int(first_element)                 second_element = s[1]                 second_element = int(second_element)                 self.adjacency_list[first_element].append((second_element, none))         elif self.directed == false:             t in self.graph_string:                 first_element = t[0]                 first_element = int(first_element)                 second_element = t[1]                 second_element = int(second_element)                 self.adjacency_list[first_element].append((second_element, none))                 self.adjacency_list[second_element].append((first_element, none))     elif self.weighted == true:         if self.directed == true:             t in self.graph_string:                 first_element = t[0]                 first_element = int(first_element)                 second_element = t[1]                 second_element = int(second_element)                 third_element = t[2]                 third_element = int(third_element)                 self.adjacency_list[first_element].append((second_element, third_element))         if self.directed == false:             t in self.graph_string:                 first_element = t[0]                 first_element = int(first_element)                 second_element = t[1]                 second_element = int(second_element)                 third_element = t[2]                 third_element = int(third_element)                 self.adjacency_list[first_element].append((second_element, third_element))                 self.adjacency_list[first_element].append((first_element, third_element))     (self.adjacency_list) 

i wish use adjacency list outputs given inputted graph, write new function:

bfs_tree(graph, start)  

which performs breadth-first search returns parents array @ end of search. example input:

graph_string = """\ d 2 0 1 """  print(bfs_tree(graph(graph_string), 0)) 

the code should return:

[none, 0] 

or given:

    graph_string = """\ u 7 1 2 1 5 1 6 2 3 2 5 3 4 4 5 """  print(bfs_tree(graph(graph_string), 1)) 

the output should be:

[none, none, 1, 2, 5, 1, 1] 

any appreciated :)