练习代码如下

# -*- coding: utf-8 -*-
"""
Spyder Editor

This is a temporary script file.
"""
import math



print("Hello, World!")
a=[1,2,3]
print(a)
b={1,2,3,3,4}

print(b)
print("a type is ",type(a))
print("b type is ",type(b))

# test for magic command, e.g. %reset equal to clear in matlab
# magic command use in python console

# test for ;
a=1;b=2;c,d=[3,4];
print(a,b,c,d)

# test for \, don't split the variable name into two lines
co\
=10
print(co)

# get help: type? in command line
help(type)

# get help from web
import requests
#from bs4 import BeautifulSoup
url="https://blog.csdn.net/"
context=requests.get(url).content
# soup=BeautifulSoup(context)
#print(content)
print("Now, i can't navigate to web. ops")

# round,pow,sqrt, cmd+i 
t1=round(2**0.5,5)
t2=2**0.5
t3=pow(2,0.5)
t4=math.sqrt(t3)
print(t1,t2,t3,t4)

print("========== how to know the function belong to which package?")

print(dir(__builtins__))

# 做好问题日志
import numpy as np
tmp=np.sqrt(2)
print('the root of 2 is ',round(tmp,4))

# from ... import *, improt the complete to current envirment
# from numpy import *
tmp=np.sqrt(2)
print('Now sqrt can be use, sqrt(2) is', round(tmp,4))
# import specified function
from numpy import exp, log,log10
tmp=log(exp(1));
print(tmp)
tmp=log10(10)
print(tmp)
# set the import function a alias
from numpy.random import random as rng
print(rng())
# 1.3.3
import numpy as np
# import matplotlib.pyplot as plt

'''python expression'''
print(123)
print(2.3e5)
print(2+3j)
print(round(np.pi,4))

a,b,c=-1,-1,-1
# tt=np.sqrt(b**2-4*a*c)
# print(tt)
# print(sqrt(-1)) # can't calculate (-1)^0.5
print(pow(-1,0.5)) # pow can 
print(dir(np))
"""e,pi,1j,sin,cos"""
print(np.pi)
print(np.e)
print(np)
print(np.sin(30))
import cmath as cm
print(cm.sqrt(-1))
tmp=complex(1,3)
print(np.real(tmp))
print(np.imag(tmp))
print(np.abs(tmp))
# use np.pi avoid to modify the value of pi, use long name to clear the meaning of variables
# set name by addPlus or add_plus
print('create a random number: ',np.round(np.random.rand(),4))
print(dir(np))
print("how to read the package documents")
print("python has the paramenter of cunction, e.g. f(x=1,y=2), you don't need remember \
      the squence of parameters")

# print(dir(1))

# f.isinteger, s.swapcase, l.reverse, l.pop
f=2.5
print('f is a float number, the value is ',f)
print('is f is a integer? ',f.is_integer())
s='Hello'
print("the swapcase of s is ",s.swapcase())
print('s is string - ',s )
l=[1,2,3]
print('l is a list ',l)
print("The reverse of l is ",l.reverse())
print("pop: delete the last value of l is",l.pop())
print("Current list l is ",l)

# object.attribute

# list, tuple and dictonary
l=[1,'a',3+4j,'Hello world!']
print("A complex list is ",l)
t=(2,3)
print("A tuple is ",t)
t=(0,)
print("A tuple has only one element is ",t)

# zeros, ones, eye, shape, size 
a=np.zeros(4)
print('zeros(4) function is ',a)
a=np.zeros((3,5)) # zeros((dim1,dim2))
print('zeros(3,5) is ',a)
a=np.zeros((3,1))
print("zeros((3,1)) is ", a)
a=np.eye(3) #
print("eye(3) is ",a)
print('np.size is the total number of the matrix, and the np.shape specify the dimension information.')
print("a's size is ",np.size(a))
print("a's shape is ",np.shape(a))

# rand & random
a=np.random.rand(3,5)
print("rand function: ",a)
a=np.random.random((3,5))
print("random fucntion: ",a)

# np.sum, mean, std ...
print("the mean of a is ",a.mean())
print("the sum of a is ",a.sum())
print("the std of a is ",a.std())

# np.array
a=np.array([[2,3,5],[7,11,13]])
print("input a array: ",a)

# np.arrange np.linspace
print("arrang(1,10,4) is ",np.arange(1,10,4))
print("linspace(1,10,11) is ",np.linspace(1,10,11))
print("logspace(1,3,3) is ",np.logspace(1,3,3))

# conecttion of array: np.hstack, h.vstack
a=np.zeros((2,3))
b=np.ones((2,3))
print("horizontal conect is ",np.hstack([a,b]))
print("vertical connect is ",np.vstack([a,b]))

# query the array
a=np.array([2,4,5])
a[0]
a[1]=100 
print("The new value of a is ",a)
a=np.array([[2,3,5],[7,11,13]])
a[0][1]
a[1][2]=100
print('New array is ',a)

# slice the array
a=np.arange(10)
print('arange(1,10) is ',a)
n=np.shape(a)
print('size(a,1) is ',n)
a=np.array([[1,2,3],[4,5,6],[7,8,9]])
print(a)
a1=a[0:3:1,2]
print(a1)
a1=a[:,0]
print("a[:,0] is : ",a1)
a=np.arange(1,10).reshape(3,3)
print(a)
print("The first row is ",a[0])
print("The first cloumn is ",a[:,0])
print("The first dimension is ", np.size(a,1))

a=np.arange(0,27).reshape(3,3,3)
print(a)
print("The first dimension is ", np.size(a,1))
print("The first dimension is ", np.size(a,1))
print("The first dimension is ", np.size(a,1))

# test 2D
a=np.arange(20)
print("a[:] ",a[:])
print("a[::] ",a[::])
print("a[5:15]",a[5:15])
print("a[5:15:3]",a[5:15:3])
print("a[5::]",a[5::])
print("a[:5:]",a[:5:])
print("a[::5]",a[::5])
print("a[-10:]",a[-10:])
print("a[-1:-10:-1]",a[-1:-10:-1])
a=np.zeros(10)
a[0:3]=np.ones(3)
print(a)
a=np.array([[1,2],[2,1]])
b=a.flatten()# return a new array
c=np.ravel(a)# assign by reference
d=a.ravel()
print(a)
print("flatten method: ",b)
print("ravel method: ",c)
b[1]=11
print("new b is ",b)
print("new a is ",a)
c[2]=22
print("nwe c is ",c)
print("new a is ",a)
print("ravel method change the value of a array")

# reshape
a=np.arange(12)
b=np.reshape(a,(3,4))
c=a.reshape((3,4))
print("a.reshape((3,4))",c)
print("a.reshape((2,3,3))",a.reshape((2,3,2)))

# use list for index of slice
a=np.arange(10,21)
print(a)
b=[2,4,5]
print("a[b]",a[b])
print("The first index in python is 0!")

# logic index
a=np.arange(-10,11)
print(a)
less_than_five=(abs(a)<5)
b=a[less_than_five]
print("The absolute value less than five is: ",b)
print("a[abs(a)<5] is",a[abs(a)<5])

# string
a='let\'s go!'
print(a)
s='123'
pie='3.1415'
x=int(s)+1
y=float(pie)+1
# z_bad=int(s)+int(pie) # 
z_good=x+y-2
# print("z_bad: ",z_bad)
print("z_good: ",z_good)
print("int function can't convert a float to int")
print("s + pie is", s+' '+pie)
s='i love'
b=str(4545)
print("(s+b)*5",(s+" "+b+' ')*5)

# latex
s="Position distribution for \$\\mu\$ = "
print("Position distribution for \$\\mu\$ = ", s)

# format
s1="The value of pi is approximately "+str(np.pi)
s2="The value of {} is approximately {:.5f}".format('pi',np.pi)
print(s1)
print(s2)
s="{1:d} plus {0:d} is {2:d}".format(2,4,2+4)
print(s)
print("{n:d} approximately same to specify the position and data type!")

# % 
print("The value of %s is approximately %.5f" %('pi',np.pi))
print("The value of {} is approximately {:.5f}".format('pi',np.pi))

# for loop
b,c=2,-1
for a in np.arange(-1,2,0.3):
    x=(-b+np.sqrt(b**2-4*a*c))/(2*a)
    print("x= {1:.4f}, a= {0:.4f}".format(a,x))
print("You can't use tab and space simultaneously for indentation")
print("The : is important for 'for','while' and 'if...elif...else'")
for i in range(1,21): print(i,i**3)


# while loop
a,b,c=2,2,-1
delta=b**2-4*a*c
while ((delta>=0)&(a>0)):
    x=(-b+np.sqrt(delta))/(2*a)
    print("a= {:.4f}, x= {:.4f}".format(a,x))
    a-=0.3
print('done')

# long time loop
for i in range(10**6): 
    if i%10**5==0 :
        print("{:.4f} percent complete ...".format((100*i)/10**6))
        # print("\n") 

# The infinite loop
# while True:
    # print("Here we go again ...") 
print("ctrl+c to end the running of scripts")
    
# matrix operation
b,c=2,-1
a=np.arange(-1,2,0.3)
x=(-b+np.sqrt(b**2-4*a*c))
print("The root list is ",x)
# for i in x: print("x is {:.4f}".format(i))
x=np.exp(a)
# for i in x: print("x is {:.4f}".format(i))

# 2F
x=np.arange(-1,1,0.1)
y=np.exp(-x**2)
for i in y: print('y(i) is {:.4f}'.format(i))

N=10
n=np.arange(0,N+1)
print(n)
mu=2
from scipy.special import factorial
y=exp(-mu)*mu**n/factorial(n,exact=True)
for i in y : print("y is {:.4f}".format(i))
 
# dot
a=np.array([1,2,3])
b=np.array([1,0.1,0.01])
c=a*b
# print("a*b=  {:.4f}".format(c))
print("a*b= ",c)
print("sum(a*b) is {:.4f}".format(np.sum(a*b)))
print("a.b= {:.4f}".format(np.dot(a,b)))
print("a x b= ",np.cross(a,b)) 

# sum
a=np.vstack((np.arange(20),np.arange(100,120)) )
print("The matrix a is ",a)
b=np.sum(a,0) # sum the column
c=np.sum(a,1) # sum the row
d=np.sum(a)
print("sum of first column is ",b)   
print("sum of second column is ",c)   
print("sum of a is ",d)   
b=a.sum(0)
print("sum of column is ",b)   
print("sum(a) is ", sum([1,2,3]))
print("np.prod is ",np.prod(a))
print("np.mean is ",a.mean())
print("np.std is {:.4f}".format(a.std()))
print("np.min is ",a.min())
print("np.max is ",a.max())
print("factorial(10) is ",np.arange(1,11).prod())
print("factorial function is ",factorial(10,exact=True))

"""scripts: '%edit' create a new file """
print("New magic command: %edit & %run")