如何根据索引位置划分列表？答案

【问题标题】：How to divide list according to index position?如何根据索引位置划分列表？
【发布时间】：2021-04-17 12:29:50
【问题描述】：

我有一个lat、lon 和alt 的组合列表，按如下所示的顺序排列，现在我想将列表分为三部分，第一部分为lat，第二部分为lon，第三部分为alt。

coords = [48.92504247289378, 9.147973368734435, 29707, 48.92504291087322, 9.147998449546572, 29707, 48.9250463088055, 9.148013780873235, 29707, 48.92505484289239, 9.148021595289876, 29707, 48.925070689333246, 9.148024125370592, 29707]

#list format = [lat,lon,alt,lat,lon,alt.....]

例外输出：

lat = [48.92504247289378,48.92504291087322,48.9250463088055....]
lon = [9.147973368734435,9.147998449546572, 9.148013780873235...]
alt = [29707,29707,29707,...]

我试过了：

Split a python list into other "sublists" i.e smaller lists

Python: Split a list into sub-lists based on index ranges

Split a list into parts based on a set of indexes in Python

还有其他一些解决方案，但都没有奏效。

谁能帮我得到预期的输出？

【问题讨论】：

标签： python python-3.x list

【解决方案1】：

怎么样：

l = [48.92504247289378, 9.147973368734435, 29707, 48.92504291087322, 9.147998449546572, 29707, 48.9250463088055, 9.148013780873235, 29707, 48.92505484289239, 9.148021595289876, 29707, 48.925070689333246, 9.148024125370592, 29707]
res = [[*l[i::3]] for i in range(3)]

输出是：

>>> res[0]
[48.92504247289378, 48.92504291087322, 48.9250463088055, 48.92505484289239, 48.925070689333246]
>>> res[1]
[9.147973368734435, 9.147998449546572, 9.148013780873235, 9.148021595289876, 9.148024125370592]
>>> res[2]
[29707, 29707, 29707, 29707, 29707]

使用numpy 的另一种可能的解决方案是：

import numpy as np
l_np = np.array(l)
n = 3
res = l_np.reshape(int(l_np.shape[0]/n), n).T

print(res)

array([[4.89250425e+01, 4.89250429e+01, 4.89250463e+01, 4.89250548e+01,
        4.89250707e+01],
       [9.14797337e+00, 9.14799845e+00, 9.14801378e+00, 9.14802160e+00,
        9.14802413e+00],
       [2.97070000e+04, 2.97070000e+04, 2.97070000e+04, 2.97070000e+04,
        2.97070000e+04]])

res 矩阵中的每一行都是所需的结果。

【讨论】：

【解决方案2】：

只需对列表进行切片即可：

coords = [48.92504247289378, 9.147973368734435, 29707, 48.92504291087322, 9.147998449546572, 29707, 48.9250463088055, 9.148013780873235, 29707, 48.92505484289239, 9.148021595289876, 29707, 48.925070689333246, 9.148024125370592, 29707]
lat = coords[::3]
lon = coords[1::3]
alt = coords[2::3]

【讨论】：

【解决方案3】：

lat = []
lon = []
alt = []

for i in range(len(coords)):
   if i % 3 == 0:
      lat.append(coords[i])
   elif i % 3 == 1:
      lon.append(coords[i])
   else:
      alt.append(coords[i])

【讨论】：