为什么我从随机选择函数中得到 IndexError？

Question

我正在尝试运行 Python 初学者书籍 Think Python 中的 this 代码，以对文本文件进行马尔可夫分析。当我运行作为解决方案提供的代码时，我得到一个 IndexError: List index out of range from the random.py 模块。我需要改变什么？

代码应该是Think Python 中练习 8 的答案，但我无法让它工作。

追溯：

Traceback (most recent call last):
  File "test.py", line 115, in <module>
    main(*sys.argv)
  File "test.py", line 111, in main
    random_text(n)
  File "test.py", line 76, in random_text
    start = random.choice(suffix_map.keys())
  File "/Library/Frameworks/EPD64.framework/Versions/7.3/lib/python2.7/random.py", line 274, in choice
    return seq[int(self.random() * len(seq))]  # raises IndexError if seq is empty

编辑：我在 .txt 文件上运行它。这是从古腾堡计划下载的一本书的文本。

Answer 1

您正在运行程序的文件没有 Gutenberg 标头。它需要有一行以：

*END*THE SMALL PRINT!

仅读取之后的文本（这发生在skip_gutenberg_header 函数中）。例如，在文件上运行代码

Header info
*END*THE SMALL PRINT!

He was very clever, be it sweetness or be angry, ashamed or only amused, at such a stroke. She had never thought of Hannah till you were never meant for me?" "I cannot make speeches, Emma:" he soon cut it all himself.

产生（作为一个例子）：

a stroke. She had never thought of Hannah till you were never meant for me?" "I cannot make speeches, Emma:" he soon cut it all himself. at such a stroke. She had never thought of Hannah till you were never meant for me?" "I cannot make speeches, Emma:" he soon cut it all himself. you were never meant for me?" "I cannot make speeches, Emma:" he soon cut it all himself. cannot make speeches, Emma:" he soon cut it all himself. be it sweetness or be angry, ashamed or only amused, at such a stroke. She had never thought of