在字符串中的每个字符前后放置一个符号 [英] Put a symbol before and after each character in a string

问题描述

我想为字符串中的每个字符添加括号.所以

HelloWorld"

应该变成:

"[H][e][l][l][o][W][o][r][l][d]"

我用过这个代码:

word = "HelloWorld"新词 = ""单词中的字母:newWord += "[%s]" % 字母

这是最直接的方法，但字符串连接非常慢.有关加速此代码的任何建议.

解决方案

>>>s = "你好世界">>>''.join('[{}]'.format(x) for x in s)'[你好，世界]'

如果字符串很大，那么使用 str.join 和列表解析将比使用生成器表达式更快且内存效率更高(https://stackoverflow.com/a/9061024/846892):

<预><代码>>>>''.join(['[{}]'.format(x) for x in s])'[你好，世界]'

<小时>

来自 Python 性能提示:

避免这种情况:

s = ""对于列表中的子字符串:s += 子串

使用 s = "".join(list) 代替.前者是构建大字符串时非常常见的灾难性错误.

I would like to add brackets to each character in a string. So

"HelloWorld"

should become:

"[H][e][l][l][o][W][o][r][l][d]"

I have used this code:

word = "HelloWorld"
newWord = ""
for letter in word:
    newWord += "[%s]" % letter

which is the most straightforward way to do it but the string concatenations are pretty slow. Any suggestions on speeding up this code.

解决方案

>>> s = "HelloWorld"
>>> ''.join('[{}]'.format(x) for x in s)
'[H][e][l][l][o][W][o][r][l][d]'

If string is huge then using str.join with a list comprehension will be faster and memory efficient than using a generator expression(https://stackoverflow.com/a/9061024/846892):

>>> ''.join(['[{}]'.format(x) for x in s])
'[H][e][l][l][o][W][o][r][l][d]'

---

From Python performance tips:

Avoid this:

s = ""
for substring in list:
    s += substring

Use s = "".join(list) instead. The former is a very common and catastrophic mistake when building large strings.

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