迭代嵌套列表并对每个元素进行操作[重复]

Question

我有一个列表列表，我正在尝试删除所有非字母字符。

我尝试使用isalpha()

data = [
    ['we', '\n\n', 'will', 'pray', 'and', 'hope', 'for', 'the', 'best'], 
    ['though', '10/3/2011', 'it', 'may', 'not', '\n\n', 'make', 'landfall', 'all', 'week', '2 000 €', 'if', 'it', 'follows', 'that', '•', 'track'],
    ['heavy', 'rains', 'capable', 'of', 'producing', 'life threatening', 'flash', '•', 'floods', '\n\n', 'are', 'possible'],
]

new_data = ''.join([i for i in data if i.isalpha()])

预期输出：

['we will pray and hope for the best', 
 'though it may not make landfall all week if it follows that track',
 'heavy rains capable of producing life threatening flash floods are possible']

我的输出：

AttributeError: 'list' object has no attribute 'isalpha'

Answer 1

由于您有嵌套列表（以及其中的字符串），因此您需要为此使用嵌套列表推导（子列表的最外层、字符串的内层和字符的最内层）和 @987654321 @ 与' ' 得到你想要的结果：

data = [['we', '\n\n', 'will', 'pray', 'and', 'hope', 'for', 'the', 'best'], 
        ['though', '10/3/2011', 'it', 'may', 'not', '\n\n', 'make', 'landfall', 'all', 'week', '2 000 €', 'if', 'it', 'follows', 'that', '•', 'track'],
        ['heavy', 'rains', 'capable', 'of', 'producing', 'life threatening', 'flash', '•', 'floods', '\n\n', 'are', 'possible']]

new_data = [' '.join(i for i in sublist if all(j.isalpha() or j == ' ' for j in i)) for sublist in data]

print(new_data)

输出：

['we will pray and hope for the best',
 'though it may not make landfall all week if it follows that track',
 'heavy rains capable of producing life threatening flash floods are possible']

正如@RonaldAaronson 向我指出的那样，如果您想从每个字符串中过滤掉非字母数字（+空格）字符，而不是完全忽略某些坏的字符串其中的字符，您可以使用它来代替：

data = [['we', '\n\n', 'will', 'pray', 'and', 'hope', 'for', 'the', 'best.'], 
        ['though', '10/3/2011', 'it', 'may', 'not', '\n\n', 'make', 'landfall', 'all', 'week', '2 000 €', 'if', 'it', 'follows', 'that', '•', 'track?'],
        ['heavy', 'rains', 'capable', 'of', 'producing', 'life threatening', 'flash', '•', 'floods', '\n\n', 'are', 'possible!']]

new_data = [
  ' '.join(x.strip() for x in (''.join(c for c in s if c.isalpha() or c == ' ') for s in sl) if x) for sl in data
]

print(new_data)

输出：

['we will pray and hope for the best',
 'though it may not make landfall all week if it follows that track',
 'heavy rains capable of producing life threatening flash floods are possible']