二维列表中的Python sum元素具有相同的第一个值 [英] Python sum elements in 2d list with the same first value
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问题描述
我正在尝试找到一种有效的方法来执行以下操作:
我有这个样本:
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]]
即对第一个元素相同的子列表的对应值求和.
非常感谢
我的代码是:
codes = list(set([element[0] for element in sample]))资源=[]对于代码中的代码:辅助=[代码]res01 = 0res02 = 0对于样本中的元素:如果元素[0] == 代码:res01 += 元素[1]res02 += 元素[2]辅助 += [res01, res02]res.append(aux)
解决方案
Using defaultdict
:
#driver 值:
IN : sample = [['no',2, 6], ['ja',5,7], ['no',4,9], ['ja',10,11], ['ap',7,12]]OUT : d = defaultdict( at 0x7f4349f17620>,{'no': [6, 15], 'ja': [15, 18], 'ap': [7, 12]})
由于输出的结构是这样的,我建议您使用 dict
类型来存储您的输出,以便将来处理它会更容易.
如果您仍然希望输出为 list
,只需映射 dict
,如下所示:
I'm trying to find an efficient way to do the following:
I have this sample:
sample = [['no',2, 6], ['ja',5,7], ['no',4,9], ['ja',10,11], ['ap',7,12]]
and would need
res = [['no', 6, 15], ['ja', 15, 18], ['ap',7,12]]
i.e. sum the corresponding values of the sublists where the first element is the same.
Thanks a lot
My code is:
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)
解决方案
Using 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 values :
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]})
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.
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]]
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