#不可变对象 int float,str,bool,tuple,改变值以后 地址就变了 print(a) print(id(a)) print(a) print(id(a)) ------------------ 140728972351312 140728972351344字典
#字典
teacher {
name : chen ,
gendar : M ,
age :18,
salary :3000
teacher[ school ] PKU
teacher.pop( age )#把年龄隐藏 出来
if age in teacher:
print(teacher[ age ])
print(teacher.get( age , O ))#如果不存在就返回默认值O。
print(teacher)
---------------------
{ name : chen , gendar : M , salary : 3000, school : PKU }
numpy
1、 arange
import numpy as np arr np.arange(10) print(arr) print(type(arr)) print(arr.ndim) print(arr.shape) print(arr.size) print(arr.dtype) ---------------------- [0 1 2 3 4 5 6 7 8 9] class numpy.ndarray (10,) int322、reshape
arr.reshape((2,5),order c ) --------------- array([[0, 1, 2, 3, 4], [5, 6, 7, 8, 9]])3 array
arr1 np.array([1,2,3,4,67])#一般放元组和list print(arr1) ---------------- [ 1 2 3 4 67]4 ones
arr2 np.ones([4,3]) print(arr2) --------------- [[1. 1. 1.] [1. 1. 1.] [1. 1. 1.] [1. 1. 1.]]5、linspace
a np.linspace(0,10,20) print(a.size) result np.sin(a) print(result) ---------------- [ 0. 0.50235115 0.86872962 0.99996678 0.86054034 0.48818921 -0.01630136 -0.5163796 -0.87668803 -0.99970104 -0.85212237 -0.47389753 0.03259839 0.53027082 0.88441346 0.99916962 0.84347795 0.4594799 -0.04888676 -0.54402111]6、向量计算
#向量计算 每次放进去一串数 然后对这些数做运算 b np.array([[1,3,4],[2,4,5]]) c np.array([4,7,2]) print(b c) print(b*c) print(np.dot(b,c)) ------------------- [[ 5 10 6] [ 6 11 7]] [[ 4 21 8] [ 8 28 10]] [33 46]
