List of articles

• Basics
• • Reserved words
  • notes
  • Code wrap
  • Multiple lines of code on one line
  • import
• data type
• • Variable
  • Number
  • string
  • List,Tuple
  • Set
  • Dictionary
  • Logical operators
• Data type operations
• • Number
  • String
  • List,Tuple,Dictionary
  • Set
• Process control
• • if
  • while
  • for
  • iter
  • enumerate
  • zip
  • Dictionary traversal
• function
• • Custom function
  • Anonymous functions
  • return

Basics

Reserved words

>>> import keyword
>>> keyword.kwlist

notes

# Single-line comments 
''' many That's ok notes Interpretation of the '''
""" This is also Multiline comment """

Code wrap

\

total = one + \
two

Multiple lines of code on one line

;

import keyword;keyword.kwlist

import

import os # Import the entire module 
from os import path # Import functions in the module 
from os import path,system # Import multiple functions 
from os import * # Import all functions 

data type

Number,String,List,Tuple,Set,Dictionary

Variable

a = b = c = 1 # Multivariable assignment 
a,b,c = 1,2,'run' # Multivariable assignment 
del a # Delete reference 
del a,b,c # To delete multiple 

type(a) # View data type 
isinstance(a,int) # Judge data type 

Number

int,bool,float,complex
+,-,*,/,//^{( integer )},%^{( Remainder )},**

string

''' Multiple lines Text '''
""" It's also Multiple lines Text """
str = ' This is a \' Escape character '
str = ' Connecting characters ' + ' Use plus sign '
str = ' Asterisk for repeated characters ' * 3
str[1:2:2] # Character slices [ rise : stop : step ]
str = r' It can also be used. r Character escape \n'

List,Tuple

[],()

a = [1,2,3,'a','b']
b = [4,'c']
a[0:2] # section 
a * 2 # repeat 
a + b # Connection list 

Set

a = {
'a','b',1,2} # How it was created 1
b = set('abc') # How it was created 2
a - b # Difference set 
a | b # Combine 
a & b # intersection 
a ^ b # a and b Elements that don't exist at the same time ( Remove intersection )

Dictionary

a = {
} # How it was created 1
b['a'] = 1 # How it was created 2
c[1] = b # How it was created 3
d = dict(a=1,b=2) # How it was created 4
e = dict([('a',1),('b',2)]) # How it was created 5
print(b.keys())
print(b.values())

Logical operators

==,!=,>,<,>=,<=
+=,-=,*=,/=,%=,**=,//=
and,or,not
in,not in
is,is not

Data type operations

Number

abscelexpfabsfloorloglog10maxminmodfpowroundsqrt

String

name = 'dan'
'Hellow %s' % name
f'Hello {
name}'

a = 1
f'{
a+1}'

List,Tuple,Dictionary

a = [1,2,'a']
a.append('b') # Additional tuple Elements in are not allowed to be modified 
del a[2] # Delete 
len(a) # length 
'a' in a # Whether there is 

Set

a = {
'a','b','c'}
a.add('d')
a.update(x)
a.remove('d') # Element does not exist will report an error 
a.discard('d') # Same as remove But there is no error 

Process control

if

age = 18
if age > 18:
print('adult')
elif age > 14:
print('young man')
else:
print('kid')

while

counter = 1
sum = 0
while True:
sum += counter
if sum > 50:
break

count = 0
while count < 5:
count += 1
else:
print(' Greater than or equal to 5')

while True: print(' One line and infinite loop ')

for

for i in range(4):
print(i)

for i in range(4):
print(i)
else:
print(' The loop ends ')

iter

a = list(range(4))
it = iter(a)
for x in it:
next(it)

enumerate

a = ['a','b','c']
for x,y in enumerate(a):
print(' Subscript :%s' % x)
print(' value :%s' % y)

zip

a = [1,2,3]
b = ['a','b','c']
for x,y in zip(a,b):
print(a,b)

Dictionary traversal

a = {
'a':1,'b':2}
for k in a:
print('key:%s' % k)
print('item:%s' % a[k])
for k,v in a.items():
print('key:%s' % k)
print('item:%s' % v)

function

Custom function

def hanshu():
pass

• Keyword parameters

def hanshu(age=18):
print(age)

• Optional parameters
  • There was no introduction age Other parameters , The second print is empty
  • Into age Parameters other than , Will tuple The form is packaged and printed

def hanshu(age,*info):
print(age)
print(info)

• Keyword optional parameters , ditto

def hanshu(age,**info):
print(age)
print(info)

Anonymous functions

lambda Parameters : result

>>> sum = lambda x,y:x+y
>>> print(sum(1,2))
3

return

Exit function

def hanshu():
return
# return None