Python从偶尔有模式的列表中提取元素到元组中

Question

我有一个列表，它有这样的模式[float, string, float string…]但偶尔在模式中它会变成[float, string, float, string, string, float string…]。我想做的是将列表的元素提取到(float, name, NoneType或str)格式的元组中，以便稍后使用它做一些事情。下面是一个小例子:

arr = [1150.1, 'James', 3323.1, 'Steve', 9323.1, 'John', 1233.1, 'Gary', 'criminal', 3293.1, 'Josh', 9232.1, 'Daniel', 'criminal']

我想提取列表，使元组看起来像这样:

(1150.1, James, NONE)

(3323.1, Steve, NONE)

(9323.1, John, NONE)

(1233.1, Gary, criminal)

(3293.1, Josh, NONE)

(9232.1, Daniel, criminal)

到目前为止，我已经尝试检查数组中的下一个索引类型，但它不工作:

for index in range(len(arr)):
if type(arr[index]) == float and type(arr[index+1]) == str:
tup = arr[index], arr[index+1], None
print(tup)
elif type(arr[index]) == float and type(arr[index+1]) == str and type(arr[index+2]) == str:
tup = arr[index], arr[index + 1], arr[index+2]
print(tup)

Answer 1

您可以使用辅助列表跟踪自最后一个浮动值以来所看到的数组元素。无论何时看到浮点数，将现有元素转换为元组并清除辅助列表:

result = []
items = []
for item in arr:
if isinstance(item, float) and items:
if len(items) < 3:
items.append(None)
result.append(tuple(items))
items = [item]
else:
items.append(item)

result.append(tuple(items))
print(result)

这个输出:

[
(1150.1, 'James', None), (3323.1, 'Steve', None),
(9323.1, 'John', None), (1233.1, 'Gary', 'criminal'),
(3293.1, 'Josh', None), (9232.1, 'Daniel', 'criminal')
]

Answer 2

您可以检查"float"， "string"模式和相应的追加:

output = list()
for i, element in enumerate(arr):
if isinstance(element, float) and isinstance(arr[i+1], str):
if isinstance(arr[i+2], str):
t = tuple(arr[i:i+3])
else:
t = tuple(arr[i:i+2]+["NONE"])
output.append(t)
>>> output
[(1150.1, 'James', 'NONE'),
(3323.1, 'Steve', 'NONE'),
(9323.1, 'John', 'NONE'),
(1233.1, 'Gary', 'criminal'),
(3293.1, 'Josh', 'NONE'),
(9232.1, 'Daniel', 'criminal')]

Answer 3

另一个解决方案:

from itertools import groupby
g1 = (g for v, g in groupby(arr, type) if v is float)
g2 = (g for v, g in groupby(arr, type) if v is str)
out = [(next(a), *[*b, None][:2]) for a, b in zip(g1, g2)]
print(out)

打印:

[
(1150.1, "James", None),
(3323.1, "Steve", None),
(9323.1, "John", None),
(1233.1, "Gary", "criminal"),
(3293.1, "Josh", None),
(9232.1, "Daniel", "criminal"),
]