Python中初始化一个5 x 3每项为0的数组,最好方法是: multilist = [[0 for col in range(5)] for row in range(3)] 如果初始化一个二维数组时,是如下,怎会发生错误: multi = [[0] * 5] * 3 因为[0] * 5是一个一维数组的对象,* 3的话只是把对象的引用复制了3次,比如,修改multi[0][0]: multi = [[0] * 5] * 3multi[0][0] = 'Love China'print mul
废话不多说,直接上代码: #coding=utf-8 def two_di_demo1(): a=[] for i in range(10): a.append([]) for j in range(10): a[i].append(0) print(a) def two_di_demo2(): a=[] for i in range(10): a.append([]) for j in range(10): a[i].append(0) print(a) b = [[0] * 10] * 10
`import heapq import numpy as np import random a = np.random.randint(50,size= (4,5)) a = np.array(a) print(a) lists = [[] for i in range(4)] for i in range(len(a)): # print(heapq.nlargest(3, range(len(a[i])), a[i].take)) lists[i].append(heapq.nlarges
1. myList = [([0] * n) for i in range(m)],n是列,m是行 >>> array=[([0]*3) for i in range(4)] >>> for i in range(4): ... for j in range(3): ... print array[i][j], ... print "\n" ... 0 0 0 0 0 0 0 0 0 0 0 0 >>> array[0][1]=1
python创建二维 list 的方法是在 list 里存放 list : l = [[1,2,3,4],[5,6,7,8],[9,10,11,12],[13,14,15,16]] numpy可以直接创建一个二维的数组: import numpy as np l = np.array([ [1,2,3,4], [5,6,7,8], [9,10,11,12], [13,14,15,16] ]) numpy二维数组获取某个值: [a, b] : a 表示行索引, b 表示列索引,就是获取第 a 行