問題描述

我正在嘗試找到一種有效的方法來執行以下操作:

I'm trying to find an efficient way to do the following:

我有這個樣本:

sample = [['no',2, 6], ['ja',5,7], ['no',4,9], ['ja',10,11], ['ap',7,12]]

并且需要

res = [['no', 6, 15], ['ja', 15, 18], ['ap',7,12]]

即將第一個元素相同的子列表的對應值相加.

i.e. sum the corresponding values of the sublists where the first element is the same.

非常感謝

我的代碼是:

codes = list(set([element[0] for element in sample]))
res=[]
for code in codes:
    aux=[code]
    res01 = 0
    res02 = 0
    for element in sample:
        if element[0] == code:
            res01 += element[1]
            res02 += element[2]
    aux += [res01, res02]
    res.append(aux) 

推薦答案

使用defaultdict:

>>> from collections import defaultdict

>>> d = defaultdict(lambda: [0,0], list())
>>> for a,b,c in sample: 
        d[a][0]+=b 
        d[a][1]+=c 

#driver 值:

IN : sample = [['no',2, 6], ['ja',5,7], ['no',4,9], ['ja',10,11], ['ap',7,12]]

OUT : d = defaultdict(<function <lambda> at 0x7f4349f17620>, 
           {'no': [6, 15], 'ja': [15, 18], 'ap': [7, 12]})

由于輸出的結構是這樣的，我建議您使用 dict 類型來存儲您的輸出，因為將來處理它會更容易.

Since the output is structured as such, I would suggest you utilise the dict type for storing your output as future processing with it will be easier.

如果您仍然希望輸出為 list，只需映射 dict，如下所示:

In case you still want the output as a list, just map the dict, as follows:

>>> [ [key]+ele for key,ele in d.items()]

=> [['no', 6, 15], ['ja', 15, 18], ['ap', 7, 12]]

這篇關于Python sum 二維列表中具有相同第一個值的元素的文章就介紹到這了，希望我們推薦的答案對大家有所幫助，也希望大家多多支持html5模板網！