Краткое пособие по языку программирования Python

python3 имя.py

a=5

>>> a=5
>>> type(a)
<class 'int'>

>>> a = 10
>>> b = "hello"
>>> c = (1, 2)
>>> type(a)
<class 'int'>
>>> type(b)
<class 'str'>
>>> type(c)
<class 'tuple'>

>>> message="hello"
>>> print(message)
hello
>>> print(message + '!')
hello!

>>> print('spam' * 3)
spamspamspam

>>> len('spam')
4

>>> S = 'spam'
>>> S[0]
's'
>>> S[2]
'a'
>>> S[-2]
'a'

>>> s = 'spameggs'
>>> s[3:5]
'me'
>>> s[2:-2]
'ameg'
>>> s[:6]
'spameg'
>>> s[1:]
'pameggs'
>>> s[:]
'spameggs'

>>> s[::-1]
'sggemaps'
>>> s[3:5:-1]
''
>>> s[2::2]
'aeg'

>>> a="123"
>>> int(a)
123
>>> float(a)
123.0
>>>

>>> "123"+str(5)
'1235'
>>>

>>> bin(256)
'0b100000000'
>>> s=bin(256)
>>> s2=s[2:]
>>> s2
'100000000'
>>>

s1=bin(257)
s2=s1[2:]
s2.count('1')

if num > 0:
    print("Число больше нуля") 
else:
    print("Число меньше или равно нулю") 

if num > 0:
    print("Число больше нуля") 
elif num < 0:
    print("Число меньше нуля")
else:
    print("Число равно нулю")

age=input("Введи свой возраст: ")
if age >=18:
   print("Доступ разрешен")
else:
   print("Доступ запрещен")

>>> i = 5
>>> while i < 15:
...     print(i)
...     i = i + 2
...
5
7
9
11
13

>>> for i in 'hello world':
...     if i == 'o':
...         continue
...     print(i * 2, end='')
...
hheellll  wwrrlldd

for number in [0, 1, 2, 3, 4]:
    print(number)
0
1
2
3
4

for number in range(10):
    if number % 2 == 0:
        print(number)

>>> for i in range(10):
...   print(i)
...
0
1
2
3
4
5
6
7
8
9

def fname(parameters):
   body

def hello():
   print("Hello, all!")

def hello(name):
   print("Hello, "+name)

hello("Вася")

# Build and return a list
def firstn(n):
  num, nums = 0, []
  while num < n:
    nums.append(num)
    num += 1
  return nums

lst=firstn(100) 
sum_of_first_n = sum(lst)
print(sum_of_first_n)
print(lst)

def pair():
  return [2,2]

print(pair())

def fib(n):    
     a, b = 0, 1
     while a < n:
       print(a, end=' ')
       a, b = b, a+b
       print()

>>> fib(2000)
0 1 1 2 3 5 8 13 21 34 55 89 144 233 377 610 987 1597

>>> def fib2(n):  
...     result = []
...     a, b = 0, 1
...     while a < n:
...         result.append(a)    
...         a, b = b, a+b
...     return result
...
>>> f100 = fib2(100)    
>>> f100            
[0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89]

>>> def fact(n):
...   if n<=1:
...     return 1
...   else:
...     return n*fact(n-1)
...
>>> fact(10)
3628800
>>>

square=lambda x: x*x
print(square(10))

print( (lambda x: x*x)(5) )

def getfun():
  return lambda x:x*x
print(getfun()(2))

a=[53,78,23,79,0,34,12,92,112]
b=sorted(a,key=lambda x: x%10)
print(b)
>>>[0, 12, 92, 112, 53, 23, 34, 78, 79]

print(sum(range(1,101)))
>>> 5050

def f(x): return x % 2 != 0 and x % 3 != 0

>>> list(filter(f,range(1,101)))
[1, 5, 7, 11, 13, 17, 19, 23, 25, 29, 31, 35, 37, 41, 43, 47, 49, 53, 55, 59, 61, 65, 67, 71, 73, 77, 79, 83, 85, 89, 91, 95, 97]

>>> sum(list(filter(f,range(1,101))))
1633

>>> list(map(lambda x: x*x,range(10)))
[0, 1, 4, 9, 16, 25, 36, 49, 64, 81]

list(reversed(list(map(lambda x: x*x,range(10))))
>>>[81, 64, 49, 36, 25, 16, 9, 4, 1, 0]

def gen():
   for i in (1,2,3):
     yield i
g=gen()
next(g)
>>>1

import random
value=random.randrange(N)

result = re.match('12', '12345678')
print result

Результат:
<_sre.SRE_Match object at 0x0000000009BE4370>

result = re.match('12', '12345678')
print result.group(0)

Результат:
12

result = re.match('23', '123456789')
print result

Результат:
None

>>> res=re.split(",","562,42,5,6,7,5,4,46,56")
>>> res
['562', '42', '5', '6', '7', '5', '4', '46', '56']
>>>

class Person:
   name="Vasya"
   def who(self):
      print("My name is "+self.name)

v=Person()
v.who()

class Person:
   name="Vasya"
   def __init__(self,name):
      self.name=name
   def who(self):
      print("My name is "+self.name)

v=Person("Маша")
v.who()

 class Person:
    population=0
    def __init__(self,name):
       self.name=name
       Person.population+=1
    def who(self):
       print("My name is "+self.name)
       print("Total: "+str(Person.population))

p1=Person("Маша")
p1.who()
p2=Person("Саша")
p2.who()

My name is Маша
Total: 1
My name is Саша
Total: 2

class SchoolMember: 
  def __init__(self, name, age):
    self.name = name
    self.age = age
    print("Initialized SchoolMember: ",self.name)
  def tell(self):
    print("Name:  Age: ", self.name, self.age)

class Teacher(SchoolMember):
  def __init__(self, name, age, salary): 
    SchoolMember.__init__(self, name, age) 
    self.salary = salary
    print ("Initialized Teacher: ", self.name)
  def tell(self): 
    SchoolMember.tell(self)
    print("Salary: ", self.salary)

class Student(SchoolMember):
  def __init__(self, name, age, marks): 
    SchoolMember.__init__(self, name, age) 
    self.marks = marks
    print("Initialized Student: ",self.name)
  def tell(self): 
    SchoolMember.tell(self)
    print("Marks: ",self.marks)

t = Teacher("Mrs. Shrividya", 40, 30000)
s = Student("Swaroop", 22, 75)
members = [t, s]
for member in members:
  member.tell()

import matplotlib
import matplotlib.pyplot as plt
import numpy as np

t = np.arange(0.0, 2.0, 0.01)
s = 1 + np.sin(2 * np.pi * t)

fig, ax = plt.subplots()
ax.plot(t, s)

ax.set(xlabel='time (s)', ylabel='voltage (mV)',
       title='About as simple as it gets, folks')
ax.grid()

fig.savefig("test.png")
plt.show()

import numpy as np
import matplotlib.pyplot as plt

x = np.linspace(0, 10, 500)
y = np.sin(x)

fig, ax = plt.subplots()

line1, = ax.plot(x, y, label='Using set_dashes()')
line1.set_dashes([2, 2, 10, 2])  

line2, = ax.plot(x, y - 0.2, dashes=[6, 2], label='Using the dashes parameter')

ax.legend()
plt.show()

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-5, 5, 100)

def sigmoid(alpha):
    return 1 / ( 1 + np.exp(- alpha * x) )

dpi = 80
fig = plt.figure(dpi = dpi, figsize = (512 / dpi, 384 / dpi) )

plt.plot(x, sigmoid(0.5), 'ro-')
plt.plot(x, sigmoid(1.0), 'go-')
plt.plot(x, sigmoid(2.0), 'bo-')

plt.legend(['A = 0.5', 'A = 1.0', 'A = 2.0'], loc = 'upper left')

fig.savefig('sigmoid.png')

import matplotlib as mpl 
import matplotlib.pyplot as plt 
import math

dpi = 80
fig = plt.figure(dpi = dpi, figsize = (512 / dpi, 384 / dpi) )
mpl.rcParams.update({'font.size': 10})

plt.axis([0, 10, -1.5, 1.5])

plt.title('Sine & Cosine')
plt.xlabel('x')
plt.ylabel('F(x)')

xs = []
sin_vals = []
cos_vals = []

x = 0.0 
while x < 10.0:
    sin_vals += [ math.sin(x) ]
    cos_vals += [ math.cos(x) ]
    xs += [x] 
    x += 0.1 

plt.plot(xs, sin_vals, color = 'blue', linestyle = 'solid',
         label = 'sin(x)')
plt.plot(xs, cos_vals, color = 'red', linestyle = 'dashed',
         label = 'cos(x)')

plt.legend(loc = 'upper right')
fig.savefig('trigan.png')

def pal(lst):
        return lst==list(reversed(lst));

print(pal([1,2,3,2,1]))
print(pal([1,2,3,2,1,1]))

>>> True
    False

def prime1(value):
        return len([x for x in range(2,value) if value%x==0])==0

print(prime1(2))
print(prime1(3))
print(prime1(4))
print(prime1(17))

def replicator(lst,n):
    res=[]
    for i in lst:
        for x in range(n):
            res.append(i)
    return res

print(replicator(['a','b','c'],5))

для каждого символа строки
  если он присутствует в наборе скобок
    если он отсутствует в словаре соответствий, т. е. это открывающая скобка
      добавить в стек этот символ
    иначе он закрывающая скобка
      если значение из словаря соответствий отличается от вершины стека
        return false
      иначе
        выкинуть последний элемент стека

return стек пуст

def check(string):
brackets_open = ('(', '[', '{', '<')
brackets_closed = (')', ']', '}', '>')
stack = []
for i in string:
    if i in brackets_open:
        stack.append(i)
    if i in brackets_closed:    
        if len(stack) == 0:
            return False
        index = brackets_closed.index(i)
        open_bracket = brackets_open[index]
        if stack[-1] == open_bracket:
            stack = stack[:-1]  
        else: return False  
return (not stack)  

def check(string):
  op = '('
  cl = ')'
  stack = []
  for i in string:
    if i==op:
      stack.append(i)
    if i==cl:    
      if len(stack) == 0:
        return False
      if stack[-1] == op:
        stack = stack[:-1]     
  return (not stack) 

print(check("(12)()"))

## суммирование цифр строки
def dsum(s):
   return sum([int(x) for x in list(s)])

def happy():
    count = 0
    for x in range(1000000):
      st = "%06d" % x
      if(dsum(st[:3])==dsum(st[3:6])):
        count +=1
    return count

print(happy())

import random
import time

def bogosort(lst):
  sortlst=sorted(lst)
  while(lst!=sortlst):
    random.shuffle(lst)

start=time.time()
random.seed()
bogosort([random.randint(1,10) for x in range(10)])
end=time.time()
print(end-start)

import random
# Щепотка цифр
str1 = '123456789'
# Щепотка строчных букв
str2 = 'qwertyuiopasdfghjklzxcvbnm'
# Щепотка прописных букв. Готовится преобразованием str2
в верхний     регистр.
str3 = str2.upper()
print(str3)
# Выведет: 'QWERTYUIOPASDFGHJKLZXCVBNM'

# Соединяем все строки в одну
str4 = str1+str2+str3
print(str4)
# Выведет: '123456789qwertyuiopasdfghjklzxcvbnmQWERTYUIOPASDFGHJKLZXCVBNM'

# Преобразуем получившуюся строку в список
ls = list(str4)
# Тщательно перемешиваем список
random.shuffle(ls)
# Извлекаем из списка 12 произвольных значений
psw = ''.join([random.choice(ls) for x in range(12)])
# Пароль готов
print(psw)
# Выведет: '1t9G4YPsQ5L7'

import random
print(''.join([random.choice(list('123456789qwertyuiopasdfghjklzxc
vbnmQWERTYUIOPASDFGHJKLZXCVBNM')) for x in range(12)]))