additional (advanced ) topic added + Cheatsheet

Author: shushrutsharma

10. Generators/fibonacci_list.py

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+
+def fib(num):
+    a = 0
+    b= 1
+    li=[]
+    for i in range(num):
+        li.append(a)
+        temp = a
+        a = b
+        b = temp + b
+    print(li)
+
+num = int(input("Enter a number: "))
+fib(num)

10. Generators/fibonacci_range.py

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+
+def fib(num):
+    a = 0
+    b= 1
+    for i in range(num):
+        yield a
+        temp = a
+        a = b
+        b = temp + b
+
+num = int(input("Enter a number: "))
+
+for i in fib(num):
+    print(i)

10. Generators/generator.py

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+
+# here we are generating our own generator function, just like a range().
+
+def generator_fn(num):
+    print("check")
+    #yield 
+    for i in range(num):
+        print("****")
+        yield i*2
+        print("####")
+
+g = generator_fn(3)
+print(g)
+print(next(g))
+print(next(g))
+print(next(g))
+#print(next(g))  # StopIteration error
+print(g)
+
+for item in generator_fn(5): 
+    print(item)
+    
+# here it goes to the generator_fn(), gets the 'i' value, pauses the function, until called for the 2nd time, 
+# and so on, it doesn't store all the no.s in the memory (just the most recent one).
+
+'''
+'yield' pauses the function and comes back to it when we do something to it, which is called 'next'.
+
+if there is the keyword 'yield' written inside the function, then python recognises that its a 
+generator function, and won't run the function until the function is being iterated.
+'''

10. Generators/our_own_forloop.py

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+
+def my_own_forloop(iterable):
+    iterator = iter(iterable)
+    while True:
+        try:
+            print(iterator)
+            print(next(iterator))
+        except StopIteration:
+            break
+
+my_own_forloop([1,2,3,4,5])

10. Generators/our_own_range.py

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+
+class OurOwnRange():
+    current = 0
+    def __init__(self,first,last):
+        self.first = first
+        self.last = last
+        
+    def __iter__(self):
+        return self
+    
+    def __next__(self):
+        print("hehehheh")
+        # if self.current < self.last:
+        #     num = OurOwnRange.current
+        #     OurOwnRange.current += 1
+        #     return num
+        # raise StopIteration
+    
+gen = OurOwnRange(0,10)
+print(gen)
+
+for i in gen:
+    print(i)
+
+'''
+loops by default deal with StopIteration error. they have build in functionality to handle them.
+'''

11. Regular Expressions/email_password_regex.py

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+
+import re
+
+email_pattern = re.compile(r"([a-zA-Z0-9_.+-]+@[a-zA-Z0-9-]+\.[a-zA-Z0-9-.]+$)")
+check_email = email_pattern.fullmatch('saurabh_1089@gmail.com')
+
+password_patter = re.compile(r"([a-zA-Z0-9@#$%]{8,}$)")
+check_password = password_patter.fullmatch('12345678')
+
+if check_email and check_password:
+    print("Both email and password are correct.")
+else:
+    print("Try again.")
+
+'''
+password is also checking for minimum 8 chars
+'''

11. Regular Expressions/regular_exp.py

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+import re
+
+string = "this is a really cool string really!"
+
+a = re.search('really',string)
+print(a)
+
+# the below 4 commands will give error if the searching string does not exist.
+print(a.span())
+print(a.start())
+print(a.end())
+print(a.group())
+
+pattern = re.compile('really')
+
+b = pattern.search(string)
+c = pattern.findall(string)
+
+pattern = re.compile('this is a really cool string really!')
+d = pattern.fullmatch('this is a really cool string really!')
+e = pattern.fullmatch('hello this is a really cool string really!')    # this should be exact match, otherwise returns none
+
+pattern = re.compile('really')
+f = pattern.match('really cool feature')    # it starts matching from the first character otherwise returns none
+g = pattern.match('yo really')
+
+print(f"b: {b}")
+print(f"c: {c}")
+print(f"d: {d}")
+print(f"e: {e}")
+print(f"f: {f}")
+print(f"g: {g}")

12. Unit Testing/__pycache__/guess_game.cpython-37.pyc

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+
+import random
+
+def run_guess(guess, answer):
+    if  0 < guess < 11:
+        if guess == answer:
+            print('you are a genius!')
+            return True
+    else:
+        print('hey bozo, I said 1~10')
+        return False
+
+if __name__ == '__main__':      # so that the game don't start while testing.
+    answer = random.randint(1, 10)
+    while True:
+        try:
+            guess = int(input('guess a number 1~10:  '))
+            if (run_guess(guess, answer)):
+                break
+        except ValueError:
+            print('please enter a number')
+            continue
+
+'''
+we test a function at a time.
+that is why it is called unit testing.
+hence we try to make pure functions and test them.
+'''

12. Unit Testing/__pycache__/guess_game.cpython-39.pyc

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+
+def add(num):
+    try: 
+        return int(num) + 5
+    except ValueError as err:
+        return err

12. Unit Testing/__pycache__/main.cpython-37.pyc

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+
+import unittest
+import script
+
+class TestMain(unittest.TestCase):  # inheriting TestCase class
+
+    def setUp(self):    # this method will run before starting all the other test methods
+        print("Starting a method/test: ")
+    
+    def test_add(self):
+        '''This is the info for this particular test'''
+        test_param = 10
+        result = script.add(test_param)
+        self.assertEqual(result,15)
+        
+    def test_add2(self):
+        test_param = 'random string'
+        result = script.add(test_param)
+        self.assertTrue(isinstance(result,ValueError))
+  
+    def tearDown(self):   # this method will run after every test method. Generally used to reset/cleaning up data variables.
+        print("Cleaning up....")
+        
+        
+class A:
+    print("\nClass A")
+
+if __name__ == '__main__':
+    unittest.main()     # this will run the entire classes present in the file
+
+
+class B:
+    print("Class B")

12. Unit Testing/__pycache__/script.cpython-37.pyc

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+
+import unittest
+import script
+
+class TestMain(unittest.TestCase):  # inheriting TestCase class
+    def test_add(self):
+        test_param = 10
+        result = script.add(test_param)
+        self.assertEqual(result,15)
+        
+    def test_add2(self):
+        test_param = 'random string'
+        result = script.add(test_param)
+        self.assertTrue(isinstance(result,ValueError))
+
+if __name__ == '__main__':
+	unittest.main()

12. Unit Testing/__pycache__/script.cpython-39.pyc

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+
+import unittest
+import guess_game
+
+class testGame(unittest.TestCase):
+    def test_game(self):
+        result = guess_game.run_guess(5,5)
+        self.assertTrue(result)
+        
+    def test_game2(self):
+        result = guess_game.run_guess(0,5)
+        self.assertFalse(result)        
+        
+    def test_game3(self):
+        result = guess_game.run_guess(15,4)
+        self.assertFalse(result)
+                
+if __name__ == '__main__':
+    unittest.main()   
+    

12. Unit Testing/__pycache__/test.cpython-39.pyc

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+
+while True:
+    try:
+        age = int(input("Enter your age: "))
+        age_in_dogs_year = 10/age
+        
+    except ZeroDivisionError:
+        print("enter age greater than 0")
+        continue
+        
+    except ValueError:
+        print("Please enter a no.")
+        break
+    
+    except ValueError:
+        print("!!!!")
+        
+    else:
+        print(f"thank you, and your age is {age}")
+        break
+        
+    finally:
+        print("I will always get printed no matter what :)")
+    
+    print("can you hear me??????")
+    

12. Unit Testing/__pycache__/test2.cpython-39.pyc

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+
+def division_fn(num1, num2):
+    try: 
+        return num1/num2
+    except (ZeroDivisionError, TypeError) as err:
+        print(f'error: {err}')
+
+print(division_fn(1,'0'))
+print(division_fn(1,0))
+print(division_fn(1,4))

12. Unit Testing/__pycache__/test_guess_game.cpython-39.pyc

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+
+# we can stop the program by raising our own errors.
+
+print("Hello!!!!")
+# raise TypeError("yo")
+raise Exception("Any message ")
+print("bye")

12. Unit Testing/guess_game.py

@@ -0,0 +1,10 @@
+# -*- coding: utf-8 -*-
+
+try:
+    age = int(input("age: "))
+    age = 10/age
+    raise ValueError("Ending the program")
+    # raise Exception("quit")
+
+except ValueError:
+    print("Please enter a no.")

12. Unit Testing/script.py

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+
+my_dict = {num:num**2 for num in range(1,11)}
+print(my_dict)
+
+random_dict = {
+    'a': 1,
+    'b': 2,
+    'c': 3,
+    'd': 4
+    }
+
+my_new_dict = {k:v**2 for k,v in random_dict.items()}
+print(my_new_dict)
+
+my_new_dict2 = {k:v**2 for k,v in random_dict.items() if v % 2 == 0}
+print(my_new_dict2)

12. Unit Testing/test.py

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+
+def only_even(item):
+    return item % 2 == 0
+
+my_list = [5,8,9,2,5,6,98,56,62]
+
+print(filter(only_even, my_list))  
+print(list(filter(only_even, my_list))) 
+print(list(map(only_even, my_list))) 
+print(my_list)

12. Unit Testing/test2.py

@@ -0,0 +1,20 @@
+
+
+import functools
+
+my_list = [1,2,3,4,5]
+
+print(list(map(lambda item: item*2, my_list)))
+
+print(list(filter(lambda item: item % 2 != 0, my_list)))
+
+print(functools.reduce(lambda acc,item: item+acc, my_list))
+
+'''
+syntax:
+lambda param: action(param)
+it automatically returns the action taken,
+it do not have any name, doesn't get stored in the memory.
+and so used only once.
+and behaves exactly like a function.
+'''

12. Unit Testing/test_guess_game.py

@@ -0,0 +1,6 @@
+
+
+a = [(0,2),(4,4),(10,-1),(5,3)]
+
+a.sort(key=lambda x:x[1], reverse=False)
+print(a)

6. Projects/Job Scheduler/bst_demo.py renamed to 13. Mini-Projects/Job Scheduler/bst_demo.py

@@ -0,0 +1,18 @@
+
+my_list = []
+
+for item in 'hello':
+    my_list.append(item)
+
+print(my_list)
+
+my_list1 = [item for item in 'Saurabh']
+print(my_list1)
+
+my_list2 = [num**2 for num in range(1,11)]
+print(my_list2)
+
+# only even squares
+my_set = {num**2 for num in range(1,11) if num**2 % 2 == 0}
+print(my_set)
+# remember that set don't contain duplicate values