Python:从字典中替换文本文件中的多个单词 [英] Python: replacing multiple words in a text file from a dictionary

问题描述

我很难弄清楚哪里出了问题.因此，我需要随机替换单词并将它们重新写入文本文件，直到对其他任何人都不再有意义为止.我选择了一些单词来进行测试，并编写了以下当前不起作用的代码:

I am having trouble figuring out where I'm going wrong. So I need to randomly replace words and re-write them to the text file, until it no longer makes sense to anyone else. I chose some words just to test it, and have written the following code which is not currently working:

# 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:

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我已经尝试了几种方法，但是作为Python的新手，这只是个猜测，而最近两天都在网上进行研究，但是我发现的大多数答案都太复杂了，让我理解或特定于该人员的代码，并且不帮我.

I've tried a few methods of this but as someone new to Python it's been a matter of guessing, and the last two days spent researching it online, but most of the answers I've found are either far too complicated for me to understand, or are specific to that person's code and don't help me.

推荐答案

确定，让我们逐步进行此操作.

OK, let's take this step by step.

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

更好地使用 with 声明在这里.另外， r 是默认模式.因此:

Better to use the with statement here. Also, r is the default mode. Thus:

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

在此块结束时，将和一起使用将自动为您调用 main.close()；您也应该在文件末尾做同样的事情.

Using with will make main.close() get called automatically for you when this block ends; you should do the same for the file write at the end as well.

现在是主要位:

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

此小节包含几个误解:

1. 遍历字典(在word_replacement中的x为 )为您提供其 keys .因此，当您以后要进行比较时，应该只检查是否word_replacement [x] == y .对它执行 [0] 只是给您替换的第一个字母.
2. 遍历字典首先要克服使用字典的目的.只需在要替换的单词上循环，然后使用 y在word_replacement 中检查(如果它们在字典中)即可.
3. y == x [1] 在两种方式上是错误的.首先，您可能打算将分配分配给 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会做您想要的事情.下次遍历 y 时，它会被新值覆盖，并且 words 数据完全不会更改.

1. Iterating over a dictionary (for x in word_replacement) gives you its keys only. Thus, when you want to compare later on, you should just be checking if word_replacement[x] == y. Doing a [0] on that just gives you the first letter of the replacement.
2. Iterating over the dictionary is defeating the purpose of having a dictionary in the first place. Just loop over the words you want to replace, and check if they're in the dictionary using y in word_replacement.
3. y == x[1] is wrong in two ways. First of all, you probably meant to be assigning to y there, not comparing (i.e. y = x[1] -- note the single = sign). Second, assigning to a loop variable doesn't even do what you want. y will just get overwritten with a new value next time around the loop, and the words data will NOT get changed at all.

---

您想要做的是创建一个可能替换单词的 new 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)

现在让我们进行一些改进.字典有一个方便的 get 方法如果存在键，则可以获取一个值；如果不存在，则可以获取一个默认值.如果我们只使用单词本身作为默认值，则会得到一个很好的简化:

Now let's do some refinement. Dictionaries have a handy get method that lets you get a value if the key is present, or a default if it's not. If we just use the word itself as a default, we get a nifty reduction:

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

您可以变成单行列表理解:

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

现在我们完成了.

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