print_tree_to_file.py

def print_tree_to_file(current_node, childattr='children', nameattr='name', indent='', last='updown',file_to_print=None):

    if hasattr(current_node, nameattr):
        name = lambda node: getattr(node, nameattr)
    else:
        name = lambda node: str(node)

    children = lambda node: getattr(node, childattr)
    nb_children = lambda node: sum(nb_children(child) for child in children(node)) + 1
    size_branch = {child: nb_children(child) for child in children(current_node)}

    """ Creation of balanced lists for "up" branch and "down" branch. """
    up = sorted(children(current_node), key=lambda node: nb_children(node))
    down = []
    while up and sum(size_branch[node] for node in down) < sum(size_branch[node] for node in up):
        down.append(up.pop())

    """ Printing of "up" branch. """
    for child in up:
        next_last = 'up' if up.index(child) is 0 else ''
        next_indent = '{0}{1}{2}'.format(indent, ' ' if 'up' in last else '│', ' ' * len(name(current_node)))
        print_tree_to_file(child, childattr, nameattr, next_indent, next_last,file_to_print=file_to_print)

    """ Printing of current node. """
    if last == 'up': start_shape = '┌'
    elif last == 'down': start_shape = '└'
    elif last == 'updown': start_shape = ' '
    else: start_shape = '├'

    if up: end_shape = '┤'
    elif down: end_shape = '┐'
    else: end_shape = ''

    # print('{0}{1}{2}{3}'.format(indent, start_shape, name(current_node), end_shape))
    file_to_print.write('{0}{1}{2}{3}'.format(indent, start_shape, name(current_node), end_shape)+"\n")

    """ Printing of "down" branch. """
    for child in down:
        next_last = 'down' if down.index(child) is len(down) - 1 else ''
        next_indent = '{0}{1}{2}'.format(indent, ' ' if 'down' in last else '│', ' ' * len(name(current_node)))
        print_tree_to_file(child, childattr, nameattr, next_indent, next_last,file_to_print=file_to_print)