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}")