如何将编号列表切片为子列表

Posted 2023-02-23

【中文标题】如何将编号列表切片为子列表

【英文标题】：How to slice numbered lists into sublists

【发布时间】：2014-01-16 13:33:51

【问题描述】：

我打开了一个文件，并使用readlines() 和split() 和正则表达式'\t' 来删除TAB，结果如下：

["1", "cats", "--,"]
["2", "chase", "--,"]
["3", "dogs", "--,"]
["1", "the", "--,"]
["2", "car", "--,"]
["3", "is", "--,"]
["4", "gray", "--,"]

现在我想通过将索引 [0] 上的整数循环为句子边界，将其提取并切成子列表，例如“猫追狗”和“汽车是灰色的”。例如，1 - 3 子列表“猫追狗”，然后继续计数 1 - 4 子列表“汽车是灰色的”，其余列表以此类推，所以我得到子列表 ["the", "car", "is", "gray" ]。我该怎么做？

我已经尝试过了，但出现错误：

无法连接 int + str

在 for 循环中将“i”检测为字符串元素而不是整数：

with open(buffer, 'r') as f:
    words = []
    for line in f:
        items = line.split('\t')[:1]
        for i in items:
            while i>1:
                i = i+1
                print i

【问题讨论】：

你尝试了什么？你说你想提取和切片“通过循环索引[0]上的整数”等等，但还没有尝试过？

我尝试使用 while 循环获取索引位置 0 上的所有数字，使其循环 1-3，然后继续计数 1-4，依此类推，但没有得到切片, 比如先得到 1-3 并 sublist "catsches dogs" 应该继续数 1-4 并 sublist "the car is gray" 等等。

然后把它放在你的问题中！如果你这样做，你更有可能得到答案。

从文件中读取“1”时，为字符串类型。您需要使用int(i) 将其转为int。

我试过了，for i in items: l = int(i) print l 但它返回 ValueError: invalid literal for int() with base 10: '' when it is counted a list.跨度>

【参考方案1】：

选择合适的数据结构使工作更容易：

container = [["1", "cats", "--,"],
             ["2", "chase", "--,"],
             ["3", "dogs", "--,"],
             ["1", "the", "--,"],
             ["2", "car", "--,"],
             ["3", "is", "--,"],
             ["4", "gray", "--,"]]

将列表嵌套在容器列表中，然后使用字典存储输出列表：

from collections import defaultdict

out = defaultdict(list)              # Initialize dictionary for output
key = 0                              # Initialize key  

for idx, word, _ in container:       # Unpack sublists
    if int(idx) == 1:                # Check if we are at start of new sentence
        key += 1                     # Increment key for new sentence
    out[key].append(word)            # Add word to list

给予：

    1: ['cats', 'chase', 'dogs'], 
    2: ['the', 'car', 'is', 'gray']

【参考方案2】：

类似：

from itertools import groupby

with open('yourfile') as fin:
    # split lines
    lines = (line.split() for line in fin)
    # group by consecutive ints
    grouped = groupby(enumerate(lines), lambda (idx, el): idx - int(el[0]))
    # build sentences from words in groups
    sentences = [' '.join(el[1][1] for el in g) for k, g in grouped]
    # ['cats chase dogs', 'the car is gray']

注意：这基于您的示例数据：

example = [
    ["1", "cats", "--,"],
    ["2", "chase", "--,"],
    ["3", "dogs", "--,"],
    ["1", "the", "--,"],
    ["2", "car", "--,"],
    ["3", "is", "--,"],
    ["4", "gray", "--,"]
]