Python:从字典中替换文本文件中的多个单词

Question

我无法弄清楚哪里出错了。所以我需要随机替换单词并将它们重新写入文本文件，直到它对其他人不再有意义为止。我选择了一些词来测试它，并编写了以下当前无法运行的代码:

# A program to read a file and replace words until it is no longer understandable

word_replacement = {'Python':'Silly Snake', 'programming':'snake charming', 'system':'table', 'systems':'tables', 'language':'spell', 'languages':'spells', 'code':'snake', 'interpreter':'charmer'}

main = open("INF108.txt", 'r+')

words = main.read().split()

main.close()

for x in word_replacement:    
    for y in words:
        if word_replacement[x][0]==y:
            y==x[1]

text = " ".join(words)

print text

new_main = open("INF108.txt", 'w')
new_main.write(text)
new_main.close()

这是文件中的文本:

Python is a widely used general-purpose, high-level programming language. It's design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than would be possible in languages such as C++ or Java. The language provides constructs intended to enable clear programs on both a small and large scale.Python supports multiple programming paradigms, including object-oriented, imperative and functional programming or procedural styles. It features a dynamic type system and automatic memory management and has a large and comprehensive standard library.Python interpreters are available for installation on many operating systems, allowing Python code execution on a wide variety of systems. Using third- party tools, such as Py2exe or Pyinstaller, Python code can be packaged into stand-alone executable programs for some of the most popular operating systems, allowing for the distribution of Python-based software for use on those environments without requiring the installation of a Python interpreter.

我已经尝试了几种方法，但作为 Python 的新手，这一直是猜测的问题，过去两天花了在线研究它，但我发现的大多数答案都太复杂了我理解，或者特定于那个人的代码，不要帮助我。

Answer 1

好的，让我们一步一步来。

main = open("INF108.txt", 'r+')
words = main.read().split()
main.close()

最好使用 with在这里声明。此外，r 是默认模式。因此:

with open("INF108.txt") as main:
    words = main.read().split()

使用 with 将使 main.close() 在此 block 结束时自动为您调用；你也应该对最后的文件写入做同样的事情。

---

现在是主要部分:

for x in word_replacement:    
    for y in words:
        if word_replacement[x][0]==y:
            y==x[1]

这个小部分包含几个错误的概念:

1. 遍历字典(for x in word_replacement)只为您提供它的键。因此，当您稍后想要比较时，您应该只检查 if word_replacement[x] == y。对其执行 [0] 只会为您提供替换的第一个字母。
2. 遍历字典违背了创建字典的初衷。只需遍历您要替换的单词，然后使用 y in word_replacement检查它们是否在字典中。
3. y == x[1] 在两个 方面是错误的。首先，您可能打算在那里分配给y，而不是比较(即y = x[1]——注意单个 = 符号)。其次，分配给循环变量甚至不能满足您的要求。 y 将在下次循环时被新值覆盖，而 words 数据根本不会改变。

---

您要做的是创建一个新的可能替换词列表，如下所示:

replaced = []
for y in words:
    if y in word_replacement:
        replaced.append(word_replacement[y])
    else:
        replaced.append(y)
text = ' '.join(replaced)

现在让我们做一些改进。字典有一个得心应手的get如果键存在，则让您获取值的方法，如果不存在，则获取默认值。如果我们只使用单词本身作为默认值，我们会得到一个很好的缩减:

replaced = []
for y in words:
    replacement = word_replacement.get(y, y)
    replaced.append(replacement)
text = ' '.join(replaced)

你可以把它变成一行 list-comprehension :

text = ' '.join(word_replacement.get(y, y) for y in words)

现在我们完成了。