Python中求中位数

瑞安3980

[[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16],[17,18,19,20]]这组列表怎么求内置列表每列的中位数，比如第一列为1,5,9,13,17，怎么求其中位数？

瑞安3980

[[1,2,3,4],
[5,6,7,8],
[9,10,11,12],
[13,14,15,16],
[17,18,19,20]]注意是求1,5,9,13,17和2,6,10,14,18等列的中位数。

瑞安3980

for j in range(length):
        sum=0.0
        for k in range(flag):
            sum+=lknn[k][j]   
        print sum/float(flag)   
            这是求均值的，可参考

tianzhizhengdao

1. import numpy as np
   
2. 
   
3. a = [[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16],[17,18,19,20]]
   
4. b = [values for sublist in a for values in sublist]
   
5. # Decent way to flat list
   
6. # import itertools
   
7. # b = list(itertools.chain.from_iterable(a))
   
8. median = [np.median(b[i::4]) for i in range(4)]
   
9. c = sum(a, [])
   
10. print(c)

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substr函数

求内置列表每列的中位数

1. #!/usr/bin/python2
   
2. 
   
3. def Median(a):
   
4.     a = sorted(a)
   
5.     l = len(a)
   
6.     l2 = l / 2
   
7.     return a[l2] if l % 2 else (a[l2] + a[l2 - 1]) / 2.0
   
8. 
   
9. 
   
10. my_list = [[1, 2, 3, 4], [5, 6, 7, 8], [9, 10, 11, 12], [13, 14, 15, 16],
    
11.            [17, 18, 19, 20]]
    
12. 
    
13. my_median = map(Median, zip(*my_list))
    
14. 
    
15. print my_median
    
16. 
    
17. # [9, 10, 11, 12]
    

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