python函数

Gather Positional Arguments with *

def print_args(*args):
    print(type(args))
    print('Positional args:', args)

print_args(1,2,3,'hello')   #<class 'tuple'>
                            #Positional args: (1, 2, 3, 'hello')

Gather Keyword Arguments with **

def print_kwargs(**kwargs):
    print (type(kwargs))
    print('Keyword args:', kwargs)

print_kwargs(first = 1,second = 2)  #<class 'dict'>
                                    #Keyword args: {'first': 1, 'second': 2}

def print_all_args(req1, *args, **kwargs):
    print('required arg1:', req1)
    print('Positional args:', args)
    print('Keyword args:', kwargs)

print_all_args(1,2,3,s='hello')  #required arg1: 1
                                 #Positional args: (2, 3)
                                  #Keyword args: {'s': 'hello'}

Docstrings

def print_if_true(thing, check):
    '''
    代码注释
    '''
    if check:
        print(thing)
        
# Use help to get the docstring of a function
help(print_if_true)
print(print_if_true.__doc__)

Lambda

def binary_operation(func,op1,op2):
    return func(op1,op2)

binary_operation(lambda op1,op2: op1 * op2, 2, 4)

Switch Case ??

def zero():
    print("You typed zero.\n")

def sqr():
    print("n is a perfect square\n")

def even():
    print("n is an even number\n")

def prime():
    print ("n is a prime number\n")

options = {0 : zero,
           1 : sqr,
           4 : sqr,
           9 : sqr,
           2 : even,
           3 : prime,
           5 : prime,
           7 : prime,}

对比

count=0
while count < 11:
    print("while count:",count)
    count = count + 1
    if(count == 11):
        break
else:
    print("else:",count)    #不会执行

count=0
while count < 11:
    print("while count:",count)
    count = count + 1
else:
    print("else:",count)    #会执行

while loop&for loop

作用域

x = 1

def change_x():
    x = 5 # Try to change x within a function
    print(x)
print(x)            #1
change_x()          #5
print(x)           #1
-----------------------------------------------------
x = 1

def change_x():
    global x # Try to change x within a function
    x=5
    print(x)
print(x)            #1
change_x()     #5
print(x)         #5

import module

import report                 #report.py
report.get_data()          #get_data()是report.py中的函数

import rp                 #report.py
rp.get_data()          #get_data()是report.py中的函数

from report import get_data,get_info
get_data()
get_info()

from report import get_data as gdata
get_data()

from source import daily,weekly   #source是文件夹 daily.py,weekly.py
daily.forcast()
weekly.forcast()

module search path

import sys
print(sys.path)