Python 莫尔斯电码不适用于短语

Question

我有这个代码：

class Morse_Code_Bin_Tree(object):
    """Class that initializes and populates a binary tree for translating morse code strings into letters.
    """
    def __init__(self):
        self.head = Node("*")

        letters = "ETIANMSURWDKGOHVF*L*PJBXCYZQ**54*3***2**+****16=/*****7***8*90"

        current = self.head
        nexts = []

        for char in letters:
            if current.left == None:
                current.left = Node(char)
            else:
                if current.right == None:
                    current.right = Node(char)
                else:
                    nexts.append(current.left)
                    nexts.append(current.right)
                    current = nexts.pop(0)
                    current.left = Node(char)

    def translate_mc_to_letter(self, mc_ltr_str):
        """method that takes a string input of morse code, traverses the morse code binary tree, and returns the correct letter for that sequnce.
            e.g. "...." => "H"
        """
        current = self.head

        for char in mc_ltr_str:
            if char == ".":
                current = current.left
            else:
                current = current.right

        return current.val


class Node(object):
    """binary node"""
    def __init__(self, char):
        self.val = char
        self.left = None
        self.right = None

尝试只解码单个字母效果很好，如下所示：

mc_tree = Morse_Code_Bin_Tree()
mc_tree.translate_mc_to_letter("....") # Prints Letter 'H'

但是当我尝试打印时 'HE'

mc_tree.translate_mc_to_letter(".... .")

...代码失败并出现此错误：

return current.val
AttributeError: 'NoneType' object has no attribute 'val'

在构造函数中创建的二叉树如下所示：

有人可以帮我解决这个问题吗？

Answer 1

方法translate_mc_to_letter仅用于返回一个字母（参见方法名称）。您应该创建另一种方法来为输入字符串中的每个“单词”调用此方法，或者直接在您的主代码中执行此操作：

s = "... --- ..."
print("".join(map(morse.translate_mc_to_letter, s.split())))  # SOS

如果您更喜欢一种方法（注意带有“s”的多种形式）：

def translate_mcs_to_letters(self, mcs_str):
    return "".join(map(morse.translate_mc_to_letter, mcs_str.split()))

并调用为：

print(morse.translate_mcs_to_letters("... --- ..."))

Python 莫尔斯电码不适用于短语

Python Morse Code not working for phrases

binary-tree

python-3.x