Viewing: graph.cpython-36.pyc
3 �d[e� � @ s d dl mZ G dd� d�ZdS )� )�dequec @ sR e Zd ZdZdd� Zdd� Zdd� Zdd � Zd d � Zd d � Z dd� Z ddd�Z dS )�Graphz� Simple oriented graph structure G = (V, E) where G is graph, V set of vertices and E list of edges. E = (tail, head) where tail and head are vertices c C s t � | _g | _t� | _d S )N)�set�vertices�edges�dict�_adj)�self� r �/usr/lib/python3.6/graph.py�__init__ s zGraph.__init__c C s | j j|� g | j|< d S )N)r �addr )r �vertexr r r � add_vertex s zGraph.add_vertexc C sH || j krtd��|| j kr$td��| jj||f� | j| j|� d S )Nztail is not a vertexzhead is not a vertex)r � ValueErrorr �appendr )r �tail�headr r r �add_edge s zGraph.add_edgec C sN y| j j||f� W n$ tk r8 tdj||���Y nX | j| j|� d S )Nz'graph does not contain edge: ({0}, {1}))r �remove�KeyErrorr �formatr )r r r r r r � remove_edge" s zGraph.remove_edgec s� y| j j� � W n" tk r2 tdj� ���Y nX | j� = x,| jj� D ] }� fdd�|D �|d d �< qHW � fdd�| jD �| _d S )Nz"graph does not contain vertex: {0}c s g | ]}|� kr|�qS r r )�.0�v)r r r � <listcomp>6 s z'Graph.remove_vertex.<locals>.<listcomp>c s$ g | ] }� |d |d fkr|�qS )r � r )r �e)r r r r : s )r r r r r r �valuesr )r r Zadjr )r r � remove_vertex+ s zGraph.remove_vertexc s � fdd�| j D �S )zU Get list of vertices where a vertex is on the right side of an edge c s g | ]}|d � kr|d �qS )r r r )r r )r r r r A s z#Graph.get_tails.<locals>.<listcomp>)r )r r r )r r � get_tails= s zGraph.get_tailsc s � fdd�| j D �S )zT Get list of vertices where a vertex is on the left side of an edge c s g | ]}|d � kr|d �qS )r r r )r r )r r r r G s z#Graph.get_heads.<locals>.<listcomp>)r )r r r )r r � get_headsC s zGraph.get_headsNc C sf |st t| j��}t� }t|g�}x>|r`|j� }||kr$|j|� |jt| jj |g ��| � q$W |S )z Breadth-first search traversal of the graph from `start` vertex. Return a set of all visited vertices ) �next�iterr r r �popleftr �extendr �get)r �startZvisitedZqueuer r r r �bfsI s z Graph.bfs)N) �__name__� __module__� __qualname__�__doc__r r r r r r r! r( r r r r r s r N)� collectionsr r r r r r �<module> s
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