如何按第二列从大到小对两列的二维数组进行排序？

Question

这是我的代码：

unique_models, count_of_models = np.unique(my_data_frame["model"], return_counts=True)
print(unique_models, count_of_models)   
                                        
[' A1' ' A2' ' A3' ' A4' ' A5' ' A6' ' A7' ' A8' ' Q2' ' Q3' ' Q5' ' Q7' ' Q8' ' R8'                         
 ' RS3' ' RS4' ' RS5' ' RS6' ' RS7' ' S3' ' S4' ' S5' ' S8' ' SQ5' ' SQ7' ' TT'] 
[1347    1 1929 1381  882  748  122  118  822 1417  877  397   69   28   33   31   29   
 39    1   18   12    3    4   16    8  336]

representative_models = np.empty((0, 2), int) 
other_models = np.empty((0, 2), int)

for models, counts in zip(unique_models, count_of_models):

    if counts < 500:

        other_models = np.append(other_models, np.array([[models, counts]]), axis=0)

    else:

        representative_models = np.append(representative_models, np.array([[models, counts]]), axis=0)

print(representative_models[representative_models[:, 1].argsort()])

[[' A1' '1347']
 [' A4' '1381']
 [' Q3' '1417']
 [' A3' '1929']
 [' A6' '748']
 [' Q2' '822']
 [' Q5' '877']
 [' A5' '882']]  

print(representative_models)

[[' A1' '1347']
 [' A3' '1929']
 [' A4' '1381']
 [' A5' '882']
 [' A6' '748']
 [' Q2' '822']
 [' Q3' '1417']
 [' Q5' '877']]

所以正如你所看到的，除了排序之外，一切都成功了，他们只是没有排序。有没有人知道另一种按第二列从大到小排序的方法？？？

外观示例：

[[' A3' '1929']
 [' Q3' '1417']
 [' A4' '1381']
 [' A1' '1347']
 [' A5' '882']
 [' Q5' '877']
 [' Q2' '822']
 [' A6' '748']]

谢谢！

Answer 1

给你：

import numpy as np
data = [[' A1', '1347'],
 [' A4', '1381'],
 [' Q3', '1417'],
 [' A3', '1929'],
 [' A6', '748'],
 [' Q2', '822'],
 [' Q5', '877'],
 [' A5', '882']] 
indices = np.argsort([int(d[1]) for d in data])
sorted_data = [data[i] for i in indices[::-1]]

Answer 2

假设你的数组如下，你可以这样做：

import numpy as np

representative_models = np.array([[' A1', '1347'],
                                  [' A4', '1381'],
                                  [' Q3', '1417'],
                                  [' A3', '1929'],
                                  [' A6', '748'],
                                  [' Q2', '822'],
                                  [' Q5', '877'],
                                  [' A5', '882']])

# convert last column to int and arg-sort in decreasing order [::-1] 
order = np.argsort(representative_models[:, 1].astype(int))[::-1]

# simply index on the input array
result = representative_models[order, :]

print(result)

输出

[[' A3' '1929']
 [' Q3' '1417']
 [' A4' '1381']
 [' A1' '1347']
 [' A5' '882']
 [' Q5' '877']
 [' Q2' '822']
 [' A6' '748']]

如何按第二列从大到小对两列的二维数组进行排序？

How to sort a 2D array of two columns, from large to small, by the second column?

python

numpy

sorting

multidimensional-array

2d