python如何大写字符串中的某些字符

问题描述

这是我想做的，但不起作用:

Here is what I want to do but doesn't work:

mystring = "hello world"
toUpper = ['a', 'e', 'i', 'o', 'u', 'y']
array = list(mystring)

for c in array:
    if c in toUpper:
        c = c.upper()
print(array)

"e"和"o"在我的数组中不是大写的.

"e" and "o" are not uppercase in my array.

推荐答案

您可以使用 str.translate()方法，让Python一步将其他字符替换为字符.

You can use the str.translate() method to have Python replace characters by other characters in one step.

使用 string.maketrans()函数将小写字符映射到大写目标:

Use the string.maketrans() function to map lowercase characters to their uppercase targets:

try:
    # Python 2
    from string import maketrans
except ImportError:
    # Python 3 made maketrans a static method
    maketrans = str.maketrans

vowels = 'aeiouy'
upper_map = maketrans(vowels, vowels.upper())
mystring.translate(upper_map)

这是替换字符串中某些字符的更快，更正确"的方法；您总是可以将mystring.translate()的结果转换为列表，但是我强烈怀疑您想首先以字符串结尾.

This is the faster and more 'correct' way to replace certain characters in a string; you can always turn the result of mystring.translate() into a list but I strongly suspect you wanted to end up with a string in the first place.

演示:

>>> try:
...     # Python 2
...     from string import maketrans
... except ImportError:
...     # Python 3 made maketrans a static method
...     maketrans = str.maketrans
...
>>> vowels = 'aeiouy'
>>> upper_map = maketrans(vowels, vowels.upper())
>>> mystring = "hello world"
>>> mystring.translate(upper_map)
'hEllO wOrld'

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