我就废话不多说了，还是直接看代码吧！
#! conding:utf-8 def quick_index(array, start, end): left, right = start, end key = array[left] while left < right: while left < right and array[right] > key: right -= 1 array[left] = array[right] while left < right and array[left] < key: left += 1 array[right] = array[left] array[left] = key return left def min_num(array, m): start, end = 0, len(array) - 1 index = quick_index(array, start, end) while index != m: if index < m: index = quick_index(array, index+1, end) else: index = quick_index(array, start, index) print(array[:m]) if __name__ == '__main__': alist = [15,54, 26, 93, 17, 77, 31, 44, 55, 20] min_num(alist, 5)
补充知识：python numpy 求top-k accuracy指标
top-k acc表示在多分类情况下取最高的k类得分的label，与真实值匹配，只要有一个label match，结果就是True。
如对于一个有5类的多分类任务
a_real = 1 a_pred = [0.02, 0.23, 0.35, 0.38, 0.02] #top-1 a_pred_label = 3 match = False #top-3 a_pred_label_list = [1, 2, 3] match = True
对于top-1 accuracy
sklearn.metrics提供accuracy的方法，能够直接计算得分，但是对于topk-acc就需要自己实现了：
#5类：0，1，2，3，4 import numpy as np a_real = np.array([[1], [2], [1], [3]]) #用随机数代替分数 random_score = np.random.rand((4,5)) a_pred_score = random_score / random_score.sum(axis=1).reshape(random_score.shape[0], 1) k = 3 #top-3 #以下是计算方法 max_k_preds = a_pred_score.argsort(axis=1)[:, -k:][:, ::-1] #得到top-k label match_array = np.logical_or.reduce(max_k_preds==a_real, axis=1) #得到匹配结果 topk_acc_score = match_array.sum() / match_array.shape[0]
以上这篇python 的topk算法实例就是小编分享给大家的全部内容了，希望能给大家一个参考，也希望大家多多支持脚本之家。
