该行if char == vowels:是错误的。它必须是if char in vowels:。这是因为您需要检查在元音列表中是否存在该特定字符。除此之外，您还需要print(char,end = '')（在python3中）将输出iiii全部打印在一行中。
最终程序将像
def eliminate_consonants(x):
vowels= ['a','e','i','o','u']
for char in x:
if char in vowels:
print(char,end = "")
eliminate_consonants('mississippi')
输出将是
iiii
def eliminate_consonants(x):
for char in x:
if char in 'aeIoU':
print(char,end = "")
看起来很简单，该语句if char in 'aeIoU'检查charstring中是否存在aeIoU。
''.join([c for c in x if c in 'aeIoU'])
此列表推导将返回仅包含字符的列表，该列表将包含字符 aeIoU
''.join(c for c in x if c in 'aeIoU')
此gen exp将返回一个生成器，而仅当字符位于 aeIoU
您可以re.findall用来仅发现字符串中的元音。编码
re.findall(r'[aeIoU]',"mississippi")
将返回在字符串ie中找到的元音列表['i', 'i', 'i', 'i']。所以现在我们可以使用str.join然后使用
''.join(re.findall(r'[aeIoU]',"mississippi"))
对于此技术，您将需要存储一个将每个非元音与None类型匹配的映射。为此，您可以使用string.ascii_lowecase。制作地图的代码是
str.maketrans({i:None for i in string.ascii_lowercase if i not in "aeIoU"})
这将返回映射。请将其存储在变量中（此处m用于地图）
"mississippi".translate(m)
您可以dict.fromkeys与一起使用sys.maxunicode。但是请记住import sys要先！
dict.fromkeys(i for i in range(sys.maxunicode+1) if chr(i) not in 'aeIoU')
现在使用str.translate。
'mississippi'.translate(m)
正如JFSebastian在下面的注释中提到的那样，您可以使用以下命令创建小写辅音的字节数组
non_vowels = bytearray(set(range(0x100)) - set(b'aeIoU'))
使用这个我们可以翻译单词，
'mississippi'.encode('ascii', 'ignore').translate(None, non_vowels)
这将返回b'iiii'。str通过使用decodeie可以很容易地将其转换为b'iiii'.decode("ascii")。
bytes返回一个字节对象，它是的不可变版本bytearray。（ ）
non_vowels = bytes(set(range(0x100)) - set(b'aeIoU'))
使用这个我们可以翻译单词，
'mississippi'.encode('ascii', 'ignore').translate(None, non_vowels)
这将返回b'iiii'。str通过使用decodeie可以很容易地将其转换为b'iiii'.decode("ascii")。
python3 -m timeit -s "text = 'mississippi'*100; non_vowels = bytes(set(range(0x100)) - set(b'aeIoU'))" "text.encode('ascii', 'ignore').translate(None, non_vowels).decode('ascii')"
100000 loops, best of 3: 2.88 usec per loop
python3 -m timeit -s "text = 'mississippi'*100; non_vowels = bytearray(set(range(0x100)) - set(b'aeIoU'))" "text.encode('ascii', 'ignore').translate(None, non_vowels).decode('ascii')"
100000 loops, best of 3: 3.06 usec per loop
python3 -m timeit -s "text = 'mississippi'*100;d=dict.fromkeys(i for i in range(127) if chr(i) not in 'aeIoU')" "text.translate(d)"
10000 loops, best of 3: 71.3 usec per loop
python3 -m timeit -s "import string; import sys; text='mississippi'*100; m = dict.fromkeys(i for i in range(sys.maxunicode+1) if chr(i) not in 'aeIoU')" "text.translate(m)"
10000 loops, best of 3: 71.6 usec per loop
python3 -m timeit -s "text = 'mississippi'*100" "''.join(c for c in text if c in 'aeIoU')"
10000 loops, best of 3: 60.1 usec per loop
python3 -m timeit -s "text = 'mississippi'*100" "''.join([c for c in text if c in 'aeIoU'])"
10000 loops, best of 3: 53.2 usec per loop
python3 -m timeit -s "import re;text = 'mississippi'*100; p=re.compile(r'[aeIoU]')" "''.join(p.findall(text))"
10000 loops, best of 3: 57 usec per loop
时序排序
translate (bytes) | 2.88
translate (bytearray)| 3.06
List Comprehension | 53.2
Regular expressions | 57.0
Generator exp | 60.1
dict.fromkeys | 71.3
translate (unicode) | 71.6
如您所见，最终的使用方法bytes是最快的。
python3.5 -m timeit -s "text = 'mississippi'*100; non_vowels = bytes(set(range(0x100)) - set(b'aeIoU'))" "text.encode('ascii', 'ignore').translate(None, non_vowels).decode('ascii')"
100000 loops, best of 3: 4.17 usec per loop
python3.5 -m timeit -s "text = 'mississippi'*100; non_vowels = bytearray(set(range(0x100)) - set(b'aeIoU'))" "text.encode('ascii', 'ignore').translate(None, non_vowels).decode('ascii')"
100000 loops, best of 3: 4.21 usec per loop
python3.5 -m timeit -s "text = 'mississippi'*100;d=dict.fromkeys(i for i in range(127) if chr(i) not in 'aeIoU')" "text.translate(d)"
100000 loops, best of 3: 2.39 usec per loop
python3.5 -m timeit -s "import string; import sys; text='mississippi'*100; m = dict.fromkeys(i for i in range(sys.maxunicode+1) if chr(i) not in 'aeIoU')" "text.translate(m)"
100000 loops, best of 3: 2.33 usec per loop
python3.5 -m timeit -s "text = 'mississippi'*100" "''.join(c for c in text if c in 'aeIoU')"
10000 loops, best of 3: 97.1 usec per loop
python3.5 -m timeit -s "text = 'mississippi'*100" "''.join([c for c in text if c in 'aeIoU'])"
10000 loops, best of 3: 86.6 usec per loop
python3.5 -m timeit -s "import re;text = 'mississippi'*100; p=re.compile(r'[aeIoU]')" "''.join(p.findall(text))"
10000 loops, best of 3: 74.3 usec per loop
时序排序
translate (unicode) | 2.33
dict.fromkeys | 2.39
translate (bytes) | 4.17
translate (bytearray)| 4.21
List Comprehension | 86.6
Regular expressions | 74.3
Generator exp | 97.1
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