在 Python 中的浮点列表列表中对数据进行分组

Question

我从 API 收到以下订单数据：

myData = [[9656.37, 0.063], [9656.32, 0.688], [9656.21, 0.729], [9656.07, 0.618], [9656.01, 0.598], [9656.0, 0.917], [9655.92, 0.417], [9655.84, 0.403], [9655.81, 1.032], [9655.6, 1.394], [9655.5, 0.043], [9655.41, 0.6], [9655.32, 0.441], [9655.31, 3.359], [9655.29, 0.15], [9655.0, 11.463], [9654.89, 0.612], [9654.88, 0.613], [9654.87, 0.602], [9654.74, 0.382], [9654.69, 0.75], [9654.63, 8.106], [9654.62, 0.8], [9654.58, 0.12], [9654.44, 0.54], [9654.38, 0.311], [9654.33, 2.758], [9654.31, 0.72], [9654.25, 0.02], [9654.14, 4.0], [9654.0, 0.155], [9653.95, 0.642], [9653.91, 0.5], [9653.83, 0.063], [9653.81, 0.6], [9653.38, 0.05], [9653.34, 0.1], [9653.31, 0.207], [9653.3, 0.001], [9653.28, 0.008], [9653.25, 3.351], [9653.03, 10.0], [9653.02, 0.651], [9652.98, 0.105], [9652.92, 0.002], [9652.9, 3.589], [9652.82, 2.07], [9652.8, 1.25], [9652.7, 0.4], [9652.66, 5.5], [9652.5, 0.006], [9652.48, 0.01], [9652.4, 0.207], [9652.39, 2.799], [9652.21, 0.174], [9652.14, 0.063], [9652.12, 8.106], [9652.09, 1.591], [9652.07, 4.0], [9652.06, 0.16], [9652.0, 0.006], [9651.9, 0.858], [9651.5, 0.006], [9651.49, 0.207], [9651.45, 0.106], [9651.37, 0.001], [9651.28, 0.7], [9651.21, 0.001], [9651.2, 1.377], [9651.16, 0.613], [9651.07, 0.16], [9651.06, 0.64], [9651.01, 0.75], [9651.0, 1.001], [9650.99, 2.637], [9650.94, 0.063], [9650.93, 2.82], [9650.87, 0.098], [9650.77, 4.782], [9650.6, 0.001], [9650.59, 12.279], [9650.56, 0.008], [9650.4, 0.008], [9650.23, 0.622], [9650.21, 0.008], [9650.2, 0.008], [9650.1, 8.106], [9650.09, 0.5], [9650.05, 1.036], [9650.0, 7.573], [9649.89, 0.5], [9649.76, 2.461], [9649.68, 0.207], [9649.6, 0.016], [9649.48, 0.059], [9649.4, 0.008], [9649.3, 10.0], [9649.29, 0.651], [9649.25, 1.286], [9649.21, 0.008] .... ]

这只是数据的一个片段，总列表很大，大约 999 个元素。 由于这个列表太大了，我正在考虑一些减少它的方法，这就是我想出的：

对数据进行分组：我只能拥有9656.37 、 9656.32 、 9656.21 ，而不是9656 。 这将接收大量的数据。 问题在于，我还需要对每个元素的第二个元素求和，所以在这种情况下（参见上面的数据）， 9656 = 0.063 + 0.688 + 0.729 + 0.598 + 0.917 。 然后，对 9655 等也应该这样做。

我对 Python 的了解还不是很高，每次我尝试解决这个问题时，我最终都会有很多for循环使代码变得一团糟，而没有接近我预期的 output: [[9656, 3.613], [9655, 19.302]...]

是否有任何关于执行此特定任务的示例，一些内置的 function 或有助于我实现这一目标的实践？ 任何形式的建议表示赞赏，在此先感谢

Answer 1

为此，您可以使用itertools.groupby ，对每个子列表的第一个元素的int值进行分组，然后对组中每个子列表的第二个元素求和：

import itertools
newData = [[k, sum(v[1] for v in g)] for k, g in itertools.groupby(myData, lambda v: int(v[0]))]

Output：

[
 [9656, 3.6129999999999995],
 [9655, 19.302],
 [9654, 20.488999999999997],
 [9653, 16.173000000000002],
 [9652, 30.038],
 [9651, 6.42],
 [9650, 40.549],
 [9649, 15.195999999999998]
]

请注意，这是因为您的输入数据按每个子列表的第一个元素排序。 如果不是这种情况，您需要先对其进行排序，例如

myData = sorted(myData, key=lambda v:int(v[0]))

Answer 2

您可以创建字典

舍入浮点数：第二项的总和

    result ={i:sum([j[1] for j in  [[round(i[0]),i[1]] for i in myData] if j[0]==i]) for i in {round(i[0]) for i in myData}}

Output：

    {9649: 12.011999999999999,
    9650: 21.044999999999998,
    9651: 28.244,
    9652: 17.986,
    9653: 27.284,
    9654: 10.309,
    9655: 27.997999999999998,
    9656: 6.902}