# 集合可以進行合併補操作,很有用 [無序]
B = {4, 5, 6, 7}
A = {1, 2, 3, 4}
C = A | B # 並集 {1,2,3,4,5,6,7}
D = A & B # 交集 {4}
E = B - A # {5,6,7}
# 實現列表對應元素相加
# 列表可以使用列表推導式
a = [1, 2, 3, 4]
b = [item*2 for item in a] # [2,4,6,8]
c = list(map(lambda x: x*2, b)) # [2,4,6,8]
myList = [item-4 for item in a if item > 4] # [2,4]
# numpy 中mat()==matrix()
import numpy as np
dd = np.mat([4, 6, 5])
rank = dd.argsort() # [0,2,1] 返回index排序[從小到大]
ee = np.mat([2, 1, 1])
ff = np.multiply(dd, ee) # 對應matlab點乘 [8,6,5]