如何识别单词中的字符并将该字母替换为另一个字符串-Python

Question

For my hangman project, in the situation that the person does guess a letter correctly, I want to be able to substitute that letter in for a '_' space.

word = input('Please enter a word for your opponent:')

letter = input('Enter a letter to try and guess the word:')

print('_ '*len(word))

if 'a' in word and letter:
    print('_ '*len(word) with 'a' in word)

For example if the word entered was 'matt,' the output would be '_a__'

Answer 1

You can use regex substitution with re.sub :

In [514]: word = 'matt'

In [515]: letter = 'a'

In [518]: re.sub(r'[^%s]' %letter, '_', word)
Out[518]: '_a__'

---

As a tip on how to continue with this approach with subsequent letters, each time the user inputs a letter, add it to letter , like this:

In [521]: new_letter = 't' # replace this with user input

In [522]: letter += new_letter

And, regex will handle the new letter when displaying, appropriately:

In [523]: re.sub(r'[^%s]' %letter, '_', word)
Out[523]: '_att'

Answer 2

You can also do this in a much simpler way.

>>> word_split = list(word)
>>> for a in range(len(word_split)):
...     if word_split[a] != letter:
...             word_split[a] = "_"
... 
>>> print(" ".join(word_split))
_ _ _ _ _ _ _ a _

However @COLDSPEED 's solution is an elegant one.

Answer 3

Here's another non-regex solution. Creates a set of indicies where the given character was found. That is then used to index characters that can be replaced in the list of underscores that's passed in ( one approach to update the passed sequence reference in your main game loop ).

def subsitute_character(character, target_word, sequence):
    indicies = {index for index, element in enumerate(target_word) if element == character}
    return ''.join(target_word[index] if index in indicies else element 
        for index, element in enumerate(sequence))

Sample Output:

>>> s = "matt"
>>> l = ["_" for _ in range(len(s))]
>>> print subsitute_character("t", s, l)
__tt