如何在将列表与前一个元素进行比较时从列表中删除项目？

Question

我正在尝试使用 Python 中的 for 循环从列表中删除项目，如果它们等于列表中的前一个元素。

当我尝试使用 del 时，我得到一个列表索引超出范围错误，通过研究我了解到这是因为使用 del 改变了我的列表的长度。

其他建议说要使用列表理解，但我不确定如何将前一个元素与当前元素进行比较，同时这样做。

这是我当前的代码：

for x in range(1, len(items)):
    if items[x] == items[x-1]:
        del items[x]
        del items[x - 1]
return result

Answer 1

尝试这个：

import pandas as pd


items = [1, 4, 4, 5, 5, 5, 6, 4, 5, 7]
remove_us = []

for x in range(1, len(items)):
    if items[x] == items[x - 1]:
        # save the index
        remove_us.append(x)

# create a Series out of your items
items_temp = pd.Series(items)
items_filtered = items_temp.drop(axis=1, index=remove_us).values
# With .values you get a numpy.ndarray
# If, for some reason, you need a list you can do:
# items_filtered = list(items_filtered)

结果：

数组（[1, 4, 5, 6, 4, 5, 7]）

---

以下是一种方法，以防您一般要删除重复项：

import pandas as pd


items_temp = pd.Series(items)
items_filtered = items_temp[~items_temp.duplicated(keep=False).values

Answer 2

我试图解决您的问题，仅在必要时更改机制：

def my_func(list):

    # copy input list for data-safety reasons
    result = list.copy()

    # empty list and 1-element list require special treatment
    if len(list)==0 or len(list)==1:
        return result

    # init current_index
    current_index = 0

    while(current_index < len(result)-1):

        # validation-check for testing purposes, comment or delete for final version
        print("at current_index: {}".format(current_index))
        print("analyzed list is: {}".format(result))
        print("analyzed list is of length: {}".format(len(result)))
        print("comparing: {} with {}".format(result[current_index], result[current_index+1]))

        if result[current_index] == result[current_index+1]:
            result.pop(current_index)
            # don't augment current_index
            current_index += 0

        else:
            # augment current_index
            current_index += 1

        print()

    return result

测试：

>>> my_func([])
[]

my_func(['a'])
['a']

>>> my_func(['a','a'])
at current_index: 0
analyzed list is: ['a', 'a']
analyzed list is of length: 2
comparing: a with a

['a']

>>> my_func(['a','a','a'])
at current_index: 0
analyzed list is: ['a', 'a', 'a']
analyzed list is of length: 3
comparing: a with a

at current_index: 0
analyzed list is: ['a', 'a']
analyzed list is of length: 2
comparing: a with a

['a']

>>> my_func(['a','b','b','c','b','c','c'])
at current_index: 0
analyzed list is: ['a', 'b', 'b', 'c', 'b', 'c', 'c']
analyzed list is of length: 7
comparing: a with b

at current_index: 1
analyzed list is: ['a', 'b', 'b', 'c', 'b', 'c', 'c']
analyzed list is of length: 7
comparing: b with b

at current_index: 1
analyzed list is: ['a', 'b', 'c', 'b', 'c', 'c']
analyzed list is of length: 6
comparing: b with c

at current_index: 2
analyzed list is: ['a', 'b', 'c', 'b', 'c', 'c']
analyzed list is of length: 6
comparing: c with b

at current_index: 3
analyzed list is: ['a', 'b', 'c', 'b', 'c', 'c']
analyzed list is of length: 6
comparing: b with c

at current_index: 4
analyzed list is: ['a', 'b', 'c', 'b', 'c', 'c']
analyzed list is of length: 6
comparing: c with c

['a', 'b', 'c', 'b', 'c']