python中固定位置的字符串替换

我正试图做一个琐碎的节目，我得到的答案问题。 我想要的是替换答案中的字符以显示为提示。例如：

answer = "I am just an example"
hintwouldbe = "I a_ j___ a_ e______"
hint2mightbe = "I am j___ an e_a___e"

我真的不知道该怎么做。尝试使用循环（对于答案中的c）和string.replace方法。也尝试了一些重新翻译和口述，但我得到了非常大的代码和难以理解。一定有更轻松的方法，这样。。。我来了

你认为哪种方式最有效/更容易实现

编辑如果我能选择替换哪些职位，那就太好了。例如：如果单词有6个字符，则将1、3和6个字符替换为_

Edit2：正确答案

稍作修改后，我选择Thomas Orozco的答案为有效答案，非常容易理解和重新创建：

    from random import random
    answer = "anything in here"
    pista = [char if random() < 0.8 else "_" for char in answer]
    pista2 = "".join(pista)
    print(pista2)

从随机导入随机
回答=“这里有任何东西”
pista=[char if random（）<0.8 else”\ux表示应答中的字符]
pista2=“”.加入（pista）
印刷品（pista2）

字符串不是您要做的事情的合适表示形式，列表会更好

import random

def make_hint(chars, frequency):
    hint_chars = [char if random.random() < frequency else "_" for char in chars]
    return "".join(hint_chars)

answer = "I am just an example"

print make_hint(answer, 0.3)
print make_hint(answer, 0.5)

---

字符串不是您试图执行的操作的合适表示形式，列表会更好

import random

def make_hint(chars, frequency):
    hint_chars = [char if random.random() < frequency else "_" for char in chars]
    return "".join(hint_chars)

answer = "I am just an example"

print make_hint(answer, 0.3)
print make_hint(answer, 0.5)

---

你应该把你心中的逻辑（如你的例子中，用6个字母的单词代替1-st、3-rd和6-th）放到结构中（例如字典）。然后，把句子分成几个单词，并运用你的逻辑。 下面是一个函数，它可以将单词中所需的位置与u交换：

def exchange(word,positions):
    chars=list(word)
        w=""
    for i in range(1,len(chars)+1):
        if i in positions:
            w+='_'
        else:
            w+=chars[i-1]
    return w

将逻辑放入字典（7-抓住单词“example”，4-抓住单词“just”）：

最后应用逻辑：

words=answer.split() # split the sentence into word
' '.join(map(lambda x: exchange(x,d.get(len(x),[])),words)) # apply the logic and join results
>>> 'I am j___ an _x_mpl_'

---

你应该把你心中的逻辑（如你的例子中，用6个字母的单词代替1-st、3-rd和6-th）放到结构中（例如字典）。然后，把句子分成几个单词，并运用你的逻辑。 下面是一个函数，它可以将单词中所需的位置与u交换：

def exchange(word,positions):
    chars=list(word)
        w=""
    for i in range(1,len(chars)+1):
        if i in positions:
            w+='_'
        else:
            w+=chars[i-1]
    return w

将逻辑放入字典（7-抓住单词“example”，4-抓住单词“just”）：

最后应用逻辑：

words=answer.split() # split the sentence into word
' '.join(map(lambda x: exchange(x,d.get(len(x),[])),words)) # apply the logic and join results
>>> 'I am j___ an _x_mpl_'

---

在指定位置替换字符：

answer = "I am just an example"   
''.join('_' if i in (1,3,6) else answer[i] for i in range(0, len(answer)))

要避免替换空白，请执行以下操作：

import string
answer = "I am just an example" 
def pr((c,i,L)):
 if (i in L and c in string.letters + string.digits):
  return '_'
 else:
  return c

''.join(map(pr,((answer[i],i,(1,3,6)) for i in range(len(answer)))))

answer = "I am just an example"
import string
import random
''.join('_' if random.randint(0, 1) and i in string.letters + string.digits else i for i in answer)

随机（假设您不想替换空白）：

---

在指定位置替换字符：

answer = "I am just an example"   
''.join('_' if i in (1,3,6) else answer[i] for i in range(0, len(answer)))

要避免替换空白，请执行以下操作：

import string
answer = "I am just an example" 
def pr((c,i,L)):
 if (i in L and c in string.letters + string.digits):
  return '_'
 else:
  return c

''.join(map(pr,((answer[i],i,(1,3,6)) for i in range(len(answer)))))

answer = "I am just an example"
import string
import random
''.join('_' if random.randint(0, 1) and i in string.letters + string.digits else i for i in answer)

随机（假设您不想替换空白）：

---

此方法会自动将每个单词的第一个字母以外的所有字母替换为“_”，然后允许基于索引重新填充提示字母。它使用三种列表理解：

def hint(a, hidxs):
    return ''.join(c[i in idxs] for i, c in enumerate(a))

a = zip(' '.join(w[0] + '_'*(len(w)-1) for w in answer.split()), answer)
_idxs = [i for i, c in enumerate(hint(a, [])) if c == '_']

以下是如何使用它们：

>>> answer = "I am just an example"
>>> a = zip(' '.join(w[0 ]+ '_'*(len(w)-1) for w in answer.split()), answer)
>>> _idxs = [i for i, c in enumerate(hint(a, [])) if c == '_']
>>> _idxs #list of indexes for every '_'
[3, 6, 7, 8, 11, 14, 15, 16, 17, 18, 19]
>>> hidxs=[]
>>> print 'Hint 1:', hint(a, hidxs)
Hint 1: I a_ j___ a_ e______
>>> hidxs=[6]
>>> print 'Hint 2:', hint(a, hidxs)
Hint 2: I a_ ju__ a_ e______
>>> hidxs=[6, 14]
>>> print 'Hint 3:', hint(a, hidxs)
Hint 3: I a_ ju__ a_ ex_____
>>> hidxs=[6, 14, 17]
>>> print 'Hint 4:', hint(a, hidxs)
Hint 4: I a_ ju__ a_ ex__p__
>>> print 'Answer:', hint(a, _idxs)
Answer: I am just an example

随机提示的程序将是：

from random import shuffle
def hint(a, hidxs):
    return ''.join(c[i in idxs] for i, c in enumerate(a))

def all_hints(answer):
    a = zip(' '.join(w[0 ]+ '_'*(len(w)-1) for w in answer.split()), answer)
    _idxs = [i for i, c in enumerate(hint(a, [])) if c == '_']
    shuffle(_idxs)
    hints = []
    print 'Press enter for next hint:'
    for i in _idxs:
        print 'Hint:', hint(a, hints),
        hints.append(i)
        raw_input()
    print 'Answer:', hint(a, hints)

---

此方法会自动将每个单词的第一个字母以外的所有字母替换为“_”，然后允许基于索引重新填充提示字母。它使用三种列表理解：

def hint(a, hidxs):
    return ''.join(c[i in idxs] for i, c in enumerate(a))

a = zip(' '.join(w[0] + '_'*(len(w)-1) for w in answer.split()), answer)
_idxs = [i for i, c in enumerate(hint(a, [])) if c == '_']

以下是如何使用它们：

>>> answer = "I am just an example"
>>> a = zip(' '.join(w[0 ]+ '_'*(len(w)-1) for w in answer.split()), answer)
>>> _idxs = [i for i, c in enumerate(hint(a, [])) if c == '_']
>>> _idxs #list of indexes for every '_'
[3, 6, 7, 8, 11, 14, 15, 16, 17, 18, 19]
>>> hidxs=[]
>>> print 'Hint 1:', hint(a, hidxs)
Hint 1: I a_ j___ a_ e______
>>> hidxs=[6]
>>> print 'Hint 2:', hint(a, hidxs)
Hint 2: I a_ ju__ a_ e______
>>> hidxs=[6, 14]
>>> print 'Hint 3:', hint(a, hidxs)
Hint 3: I a_ ju__ a_ ex_____
>>> hidxs=[6, 14, 17]
>>> print 'Hint 4:', hint(a, hidxs)
Hint 4: I a_ ju__ a_ ex__p__
>>> print 'Answer:', hint(a, _idxs)
Answer: I am just an example

随机提示的程序将是：

from random import shuffle
def hint(a, hidxs):
    return ''.join(c[i in idxs] for i, c in enumerate(a))

def all_hints(answer):
    a = zip(' '.join(w[0 ]+ '_'*(len(w)-1) for w in answer.split()), answer)
    _idxs = [i for i, c in enumerate(hint(a, [])) if c == '_']
    shuffle(_idxs)
    hints = []
    print 'Press enter for next hint:'
    for i in _idxs:
        print 'Hint:', hint(a, hints),
        hints.append(i)
        raw_input()
    print 'Answer:', hint(a, hints)