将None更改为在字符串列表中浮动(Python)

list(map(lambda x: (0.0,)+x[1:] if x[0] is None else x,mylist))

>>> list(map(lambda x: (0.0,)+x[1:] if x[0] is None else x,mylist))
[(0.5, 'house', 'flower'), (0.213, 'garden', 'flowerpot'), (0.0, 'mulch', 'hunting'), (0.9, 'flower', 'tulip'), (0.34, 'party', 'music'), (0.0, 'piano', 'trowel'), (0.138, 'fertilizer', 'cow')]

代码工作如下:因此,我们使用 lambda x: (0.0,)+x[1:] if x[0] is None else x 作为映射函数。

三元运算符 x[0] is None ,我们返回 (0.0,)+x[1:] 0.0 作为第一个元素,以及 x[1:] 作为剩余元素。如果第一个元素不是 None x .

至少一个元素

list(map(lambda x: (0.0,)+x[1:] if x and x[0] is None else x,mylist))

您可以使用列表理解:

l = [(0.5, 'house', 'flower'),
    (0.213, 'garden', 'flowerpot'),
    (None, 'mulch', 'hunting'),
    (0.9, 'flower', 'tulip'),
    (0.34, 'party', 'music'),
    (None, 'piano', 'trowel'),
    (0.138, 'fertilizer', 'cow'),
]

l = [ (0.0,)+ x[1:] if x[0] is None else x  for x in l]

[(0.5, 'house', 'flower'), (0.213, 'garden', 'flowerpot'), (0.0, 'mulch', 'hunting'), (0.9, 'flower', 'tulip'), (0.34, 'party', 'music'), (0.0, 'piano', 'trowel'), (0.138, 'fertilizer', 'cow')]