Python tutorial

-- coding: utf-8 --
 """
 Created on Thu Oct 31 06:42:56 2019
 Quick Python tutorial. Based od Python 3
 @author: token
 """
 Basics
 Print text value
 print("Hello World")
 Print number
 print(123)
 Assign None value (like null)
 x = None
 print(x)
 Check datatype
 type(123)
 Help
 help(str)
 Numbers
 Integer number example
 print(3)
 value type
 type(33)
 Float example
 print(3.14)
 complex numbers
 "j" sign and parenthesis
 x = (15 + 5j)
 check datatype
 type(x)
 Strings
 'Hello World'
 or
 "Hello World"
 String concatenation and variables
 a = "Hello "
 b = "World"
 c = a+b
 print(c)
 is is eqwual to:
 print("Hello "+'World')
 string multiplication
 "Hello World! " * 3
 Substring from left. Numbers from 0
 "Hello World! "[1]
 "Hello World! "[6:12]
 or
 var = "Sample text"
 var[7]
 Substring from right
 "Hello World! "[-5]
 String reverse in Python
 x = "I like learning Python"
 print(x[::-1])
 Lower case and upper case on string Value
 x = "I like learning Python"
 print(x.upper())
 print(x.lower())
 You can insert variable into string value.
 Use %s if you want to insert string value.
 Use %d if you want to insert integer number.
 Use %f if you want to insert float number.
 Float with defined fraction %.f
 x = 28
 print("Ann is %d years old." % x)
 You can use more than one variable
 x = 28
 y = "Paris"
 print("Ann is %d years old and she is from %s" % (x, y))
 Insert more than one value with same datatype
 name = "Ann"
 age = 29
 score = 78.5
 year = 2019
 city = "Paris"
 print("%s is from %s. She is %d years old. She wrote last exam in %d and reach %.1f points" 
       % (name, city, age, year, score ))
 Check the number of occurrences of the character or string in other string
 x = "I like learning Python. Python is the best programming language"
 print(x.count("g"))
 print(x.count("Python"))
 You can also check the position of string or character in other strig
 Python will return position of first occurence
 x = "I like learning Python. Python is the best programming language"
 print(x.index("g"))
 print(x.index("Python"))
 Check start and end string parts
 It will return True or False
 x = "I like learning Python"
 print(x.startswith("I like"))
 print(x.endswith("Pyt"))
 Create list of strings from other string
 You need to choose delimiter for example space or "," or ";"
 x = "I like learning Python. Python is the best programming language"
 print(x.split(" "))
 Operators
 Arithmetic Operators
 use +, -, *, /
 sum
 4 + 2 + 12.2
 multiplication
 x = 5 * 5
 x
 devide
 5 / 2
 devide withot rest
 51 // 2
 rest from division
 7 % 3
 power
 10 **2
 Other way to use arithetic operators - Assignment
 x = 17
 x += 2
 x
 example with power
 x = 12
 x **= 2
 x
 If you want to do longer calculation
 x = (2+6) * 2 / 3
 print(x)
 Example with string value
 #
 x = []
 x += "Hello World"
 print(x)
 Comparision operators
 Comparision operators will retur True or False values
 You can use them in conditional statement
 x= 123
 print(x==120)
 print(x==123)
 print(x>=123)
 print(x<=123) print(x>120)
 print(x<123)
 Logical operators and, or, not, in
 and
 x,y=1,2
 if x<10 and y>=2:
     print("%d is lower than 10 and %d is greater or equal 2" %(x,y))
 or
 x,y=9,10
 if x<10 or y<10:
     print("x or y is lower than 10")
 in
 x = 44
 if x in [1,2,3,4,5]:
     print("x is in the list")
 else:
     print("x is outside the list")
 not in
 x = 4
 if x not in [1,2,3,4,5]:
     print("x is not in the list")
 else:
     print("x is in the list")    
 is / is not
 x, y = 1,2
 print(x is y)
 print(x is not y)
 not
 print(not False)
 print(not True)
 Variables and datatpes
 Variable name cannot start from number
 upper and lower case are important
 You can use a-z, 0-9 and "-"
 don't use pyhon command to name variables
 In Python you don't need to declare variable before using them
 You can create more than one variable in one line
 x,y,z = 1,2,3
 print(x)
 print(y)
 print(z)
 Check datatype
 variable with string datatype
 x  = "Python"
 type(x)
 variable with list datatype
 x = []
 type(x)
 variable with float datatype
 x = 123.890
 type(x)
 Data collections
 Tuples
 Tuple can handle values with different datatype
 Tuple cannot be sort
 Create tuple using ()
 Each element has index
 tuple can handle diffrent datatypes
 You cannot modify list elements
 x = 12, "Python", 0.123, (12+5j), (1,2,3,4,5,6)
 type(x)
 You can index tuple elements. Index numbers start from 0 value
 x[2]
 x[0]
 You can also start from right
 x[-1]
  
 x[-1][3]
 Adding new values to tuple. "," is needed
 y = 'Hello World !',
 z = x + y
 z
 Tuple multiplication
 print(z * 3)
 Checking index number of tuple elements
 z.index("Python")
 index will return index of value first occurence
 (z*3).index("Python")
 Count occurence of tuple element
 z.count("Python")
 or
 (z*3).count("Python")
 number of tuple elements
 len(z)
 Sum, min, max on tuple elements, when tuple have only numeric values
 a = (1, 2, 3.14, 8)
 min
 min(a)
 max
 max(a)
 sum
 sum(a)
 Python lists
 Lists can handle different datatypes values
 Create list using []
 l = [1, 2, 'Python', "Learn more"]
 type(l)
 You can modify list elements
 l[2] = 'abc'
 l
 You can index list elements. Index numbers start from 0 value
 l[2]
 l[0]
 You can also start from right
 [-1]
 You can add new values
 m = l + [1,2,3,4]
 m
 or
 l.append("New string value")
 l
 Choose element from list
 l[-2]
 Choose list elements
 l[0:3]
 You can change more than one element
 l[0:2] = [1,2,3,4,5,6]
 l
 Remove list element using list value
 l.remove('Learn more')
 l
 Delete list elements using index number
 del(l[1:2])
 l
 Sort list elements
 l.sort
 l
 Sort list descending
 n = [1,5,2,6,8,3.14]
 n.sort(reverse=True)
 n
 List elements generator. List of values from 0 to 99
 o = list(range(1,100))
 o
 How to use arithmetic operations with lists
 a = [1,2,3]
 b = [4,5,6]
 c = a + b
 print(c)
 Sets in Python
 You can create set using {}.
 Set can contain values of different datatypes
 Elements cannot be repeated
 Elements order is not important
 You cannot sort or index sets
 Create set
 x = {1,2,3,4,1,2,3,4,"Hello World", "Python", "Python",1,2,3,4}
 x
 You can add new elements to set
 x.add(987)
 x
 You can remove elements from set
 x.remove(987)
 x
 Dictionaries in Python
 Key-value datatype
 Keys need to be uniqe
 Dicts have keys, not indexes
 You can kreate keys also using string values
 d ={1:"Python", 2:"is", 3:"the", 4:"best", 7: "programming", 9:"language"}
 d
 Choosing value using key number
 d[1]
 d[9]
 You can modify value using key
 d[1] = "Python 3"
 d
 You can delete value
 del d[7]
 d
 You can list keys
 d.keys()
 # #  Out[107]: dict_keys([1, 2, 3, 4, 9])
 You can list values
 d.values()
 # # Out[108]: dict_values(['Python 3', 'is', 'the', 'best', 'language'])
 zip() function can join different type of collection
 my_tuple = 12, "Python", 0.123, (12+5j), (1,2,3,4,5,6)
 my_list = [1, 2, 'Python', "Learn more"]
 my_set = {1,2,3,4,1,2,3,4,"Hello World", "Python", "Python",1,2,3,4}
 my_dict = {1:"Python", 2:"is", 3:"the", 4:"best", 7: "programming", 9:"language"}
 You can reate list using zip() function
 zip_list = list(zip(my_tuple, my_list, my_set, my_dict))
 zip_list
 You can create dict using zip() function
 a=(1,2,3)
 b=("Hello","Python","!")
 zip_dict = dict(zip(a,b))
 zip_dict
 if statement in Python
 You need use ":" in condition line
 use 4 space before result code
 use == if you want use equal condition
 x = 100
 if x > 100:
     print("Better than 100")
 elif x == 100:
     print("x is 100")
 elif x < 100:
     print("x is less then 100")
 else:
     print("Never mind")
 Conditional statements
 x = 10.1
 print(x, 'is', 'greater than 100' if x > 100 else 'is not greater than 100')
 For loop in Python
 for loop example
 w = [1,2,3,4,5,6,7]
 for i in w:
     print(i)
 numbers from 0 to 99
 for i in range(100):
     print("number: " + str(i))
 numbers from 1 to 100
 for i in range(100):
     print("number: " + str(i+1))
 For loop with step by 2
 Prints out 3,5,7
 for x in range(1, 10, 2):
     print(x)    
 While loop
 n = 10
 while n < 101:
     print("current number: ", n)
     n += 2
 using break, if you want to quit while loop ealier
 n = 10
 while n < 101:
     print("current number: ", n)
     n += 2
     if n == 50:
         break
 continue
 n = 10
 while n < 101:
     print("current number: ", n)
     n += 2
     if n == 50:
         continue
     print("After continue:" ,n*2)
 Break and continue can be use also in for loop
 Loop using sequences
 List crate
 [i for i in range(4)]
 or
 [i**2 for i in range(4)]
 You can use if statement inside
 [i**2 for i in range(4) if i == 4]
 Functions
 You can define your own functions using def statement
 function without input parm
 def myFunction():
     print("Hello")
 myFunction()
 function with input parm
 def myNewFunction(x):
     return x * 10
 myNewFunction(5)
 function with more thane one parm
 def myNewFunction2(x, y, z):
     return x * y * z
 myNewFunction2(1,2,3)
 Lambda statement
 You can create new function using lambda statement
 myLambdaFunction = lambda x: x ** 10
 myLambdaFunction (2)
 classess
 create class
 class NewClass:
     myVariable = "Python tutorial"
 def myFunction(self):     return ("Sample text")
 initialize class
 z = NewClass()
 use class
 print(z.myVariable)
 print(z.myFunction())
 Libraries in Python
 math lib
 import math
 math.e
 math.sin(0)
 math.pi
 Random values lib
 import random
 random value
 random.random()
 random.seed(100)
 math , statistic, matrix
 import numpy
 numpy.abs(-100)