比较列表python的列表元素

Question

我有一个列表，我需要比较所有元素的第0项和第2项。如果这两项相等，我想把第1项和第3项相加。更清楚地说：

list1 = [['diez.hn','Arts','Austria','8'], ['diez.hn','Entertainment','Austria','12']]
element 0 of list1: ['diez.hn','Arts','Austria','8']
element 1 of list1: ['diez.hn','Entertainment','Austria','12']

我需要的是：

list_ok = [['diez.hn','Arts - Entertainment','Austria','20']]

我试过这样的方法：

reader = [['diez.hn','Arts','Austria','8'], ['diez.hn','Entertainment','Austria','12']]
reader2 = [['diez.hn','Arts','Austria','8'], ['diez.hn','Entertainment','Austria','12']]
    for item in reader:
        for item2 in reader2:
            if item[0] and item[2] == item2[0] and item2[2]:
                item[1] = item[1] + item2[1]
                item[3] = item[3] + item2[3]

Answer 1

这种方法对列表进行排序，然后使用itertools.groupby()对位置0和2处具有相同元素的子列表进行分组：

import itertools
import operator

list1.sort(key=operator.itemgetter(0, 2))

list_ok = []

for k, group in itertools.groupby(list1, key=operator.itemgetter(0, 2)):
    group = list(group)
    list_ok.append([
        k[0], 
        ' - '.join(item[1] for item in group), 
        k[1], 
        str(sum(int(item[3]) for item in group)), 
    ])