Question

我在将一线循环以下转换为多线循环时遇到麻烦。这是原始代码：

sequences = [[[item.strip() for item in itemset.split(",")] for itemset in sequence] for sequence in sequences]

我尝试过的多行循环：

for sequence in sequences:
 for itemset in sequence:
    for item in itemset.split(","):
       sequences.append(item.strip())

它与原始版本不兼容。有想法吗？

Answer 1

您原来的问题会使用相同的数据名称（sequences）重新分配结果。在这里，我将结果分配给变量result。

鉴于您未提供示例数据，我只是做了一些（sequences）。

您原来的列表理解是嵌套的（请注意方括号），每一层都创建一个单独的列表。

[[[x.strip() for x in something] for something in something_else] for something_else in sequences]。

我通过为每个for-loop创建一个新列表来重新创建该结构，并随其添加以匹配原始列表理解。

# Sample data.
sequences = [['the, quick, brown fox'], ['jumped, over, the lazy dog']]

# Solution.
result = []
for sequence in sequences:
    inner_list = list()
    result.append(inner_list)
    for itemset in sequence:
        inner_list_2 = list()
        inner_list.append(inner_list_2)
        for item in itemset.split(","):
            inner_list_2.append(item.strip())
>>> result
[[['the', 'quick', 'brown fox']], [['jumped', 'over', 'the lazy dog']]]

# Original list comprehension.
>>> [[[item.strip() for item in itemset.split(",")] 
      for itemset in sequence] 
     for sequence in sequences]
[[['the', 'quick', 'brown fox']], [['jumped', 'over', 'the lazy dog']]]

一行循环到多行python

1 个答案: