需要将列表拆分为嵌套列表

Question

我正在尝试根据行尾和 # 创建子列表：例如文件包含：

#
2.1,-3.1
-0.7,4.1
#
3.8,1.5
-1.2,1.1

并且输出需要是： [[[2.1, -3.1], [-0.7, 4.1]], [[3.8, 1.5], [-1.2, 1.1]]]

但编码后：

results = []
fileToProcess = open("numerical.txt", "r")
for line in fileToProcess:
   results.append(line.strip().split(' '))
print(results)

我得到： [['#'], ['2.1', '-3.1'], ['-0.7', '4.1'], ['#'], ['3.8', '1.5'], ['-1.2' , '1.1']]

Answer 1

假设 Python 作为一种编程语言，并且假设您希望输出完全像这样：

[[[2.1, -3.1], [-0.7, 4.1]], [[3.8, 1.5], [-1.2, 1.1]]]

操作方法如下：

我对代码进行了注释以便更好地理解。如果有什么不清楚的地方请告诉我。

fileToProcess = open("numerical.txt", "r")
results = []
hashtag_results = []

# For each line, we have two cases: either the line contains hashtags or contains numbers.
for line in fileToProcess:

    '''
    If the line doesn't contain hashtags, then we want to:
        1. Separate the text by "," and not spaces. 
        2. Parse the text as floats using list comprehension. 
        3. Append the parsed line to hashtag_results which contains 
        all lists between two hashtags.
    '''

    if not line.startswith("#"):
        line_results = [ float(x) for x in line.strip().split(',')]
        hashtag_results.append(line_results)

   '''
   If the line contains a hashtag AND the hastag_results ISN'T EMPTY:
   then we want to append the whole hashtag_list to the final results list.
   '''
        
    if line.startswith("#") and hashtag_results:
        results.append(hashtag_results)
        hashtag_results = []

# For the final line, we append the last hashtag_results to the final results too.
results.append(hashtag_results)

print(results)

[[[2.1, -3.1], [-0.7, 4.1]], [[3.8, 1.5], [-1.2, 1.1]]]

Answer 2

总体思路在您的 OP 中看起来不错，但您需要按 ","（而不是 " "）拆分，并将 list 附加到 results ，其中 list 是数值列表。

另一个问题是您在完成文件后没有关闭它。我建议使用 open() 支持的内置上下文管理器结构 (https://book.pythontips.com/en/latest/context_managers.html)，一旦您离开上下文管理器范围，它将自动关闭文件。

从文件中解析数据是 Python 中的一项常见数据处理任务，因此可以通过列表理解以更“pythonic”的方式实现。

# use a context manager, so once you leave the `with` block,
# the file is closed(!)
with open("numerical.txt", "r") as fileToProcess:
  results = [
    # split the line on "," and interpret each element as a float
    [float(val) for val in line.strip().split(",")]

    # iterate through each line in the file
    for line in fileToProcess

    # ignore lines that just have '#'
    if line.strip() != "#"
  ]

# here, the file would be closed, and `results` will contain the parsed data
# result = [[[2.1, -3.1], [-0.7, 4.1]], [[3.8, 1.5], [-1.2, 1.1]]]

需要将列表拆分为嵌套列表

Need to split list into a nested list

python

nested-lists