一行循环到多行python

Question

我无法将一行循环恢复到多行循环。 这是原始代码：

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

我试过多行循环：

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

它不像原来的那样工作。 任何想法？

Answer 1

您的原始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 。

鉴于您没有提供样本数据，我只是做了一些（ sequences ）。

您的原始列表理解是嵌套的（注意括号），每个层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] 。

我通过创建一个包含每个for-loop的新列表来重新创建该结构，随着它继续匹配原始列表理解。

# 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']]]