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Output

This block of code is running for number. 1

This block of code is running for number. 2

This block of code is running for number. 3

This block of code is running for number. 4

This block of code is running for number. 6

This block of code is running for number. 7

This block of code is running for number. 8

This block of code is running for number. 9

This block of code is running for number. 10

This block of code is running for number. 11

10. For Loop

A for loop is controlled by a sequence, such as an iterator, a list, or another collection type. The body of the loop is run for each item in the series, and the loop finishes when the sequence is exhausted.

for var in range(1, 10): print("Loop running. ") print('Loop exited')

Output

11. Range Function

Programmers use Python's range() to run an iteration for a specified number of times. It takes the following arguments:

Start: the number that the sequence of integers should begin with.

Stop: the integer before which the integer sequence should be returned. Stop – 1 is the end of the integer range. Stop – 1 is the end of the integer range.

Step: the integer value that determines the increase between each integer in the sequence.

for var in range(1, 20, 2): print("Loop running with step size of 2. ") print('Loop exited')

Output

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

Loop running with step size of 2.

For-If- Else Statements Combined

For-if-else statements allow you to provide conditional statements inside the loops including the if, else and elif.

for var in range(1, 11): if(var%2==0): print("This is even integer") else: print("This is odd integer") print('Loop exited')

Output

This is odd integer

This is even integer

This is odd integer

This is even integer

This is odd integer

This is even integer

This is odd integer

This is even integer

This is odd integer

This is even integer

Modules in Python

We can import other python module codes by importing file/function from other python modules using the import statement of Python. The import statement is the most frequent method of triggering the import mechanism, but it isn’t the only means for import.

import random for i in range(5): print("Random integer is", random.randint(1, 30))

Output

Random integer is 8

Random integer is 10

Random integer is 11

Random integer is 3

Random integer is 8

We can also use the from statement to import a specified method of the module

from collections import Counter List = [1, 2, 3, 4, 5, 5, 1] Cnt = Counter(List) print(Cnt)

Output

Function

A function is a reusable, ordered block of code that performs a single, connected activity. Functions provide your program more modularity and allow you to reuse a lot of code. Python also includes several built-in functions such as print(), but you may also construct your own.

def checkParity(num): if(num % 2 == 0): print("Number is even") else: print("Number is odd") num = 5 checkParity(num)

Output

Here’s a function that returns something:

def checkParity(num): if(num % 2 == 0): return "Number is even" else: return "Number is odd" num = 4 parity = checkParity(num) print(parity)

Output

Exception Handling

In programming languages, exceptions are circumstances in which an error occurs that prevents the code from continuing. If you divide anything by zero, for example, a runtime exception will occur, and the program will crash. However, you may write what to do in the program if such a case arises, which is known as exception handling. In Python, the main code is written inside the try block. The exceptions are handled inside the except block. The finally block is always executed regardless of an exception occurring.

def divideBy(num): try: print(10 / num) except: print("Cannot divide by 0") finally: print("Division finished") num = 0 divideBy(num)

Output

Cannot divide by 0

Lists in Python

A list is a sequence of heterogeneous elements in Python. It's similar to an array, except it may hold data from several sources. The values of a changeable list can be changed. We can use indexing to parse each value of the list or to access a list element.

>>> list = ['truck', 'car', 'submarine', 'jet'] >>> list ['truck', 'car', 'submarine', 'jet'] >>> list = ['truck', 'car', 'submarine', 'jet'] >>> list[0] 'truck' >>> list[1] 'car' >>> list[2] 'submarine' >>> list[3] 'jet'

We can also use negative indexes with lists:

>>> list = ['truck', 'car', 'submarine', 'jet'] >>> list[-2] 'submarine' >>> list[-3] 'car' >>> 'The <> is larger than a <>.'.format(list[-2], list[-3]) 'The submarine is larger than a car.'

Modifying a Value of an Element in a List

>>> list = ['truck', 'car', 'submarine', 'jet'] >>> list[1] = 'bike' >>> list ['cat', 'bike', 'rat', 'elephant'] >>> list[2] = list[1] >>> list ['cat', 'bike', 'bike', 'elephant'] >>> list[-1] = 54321 >>> list ['cat', 'bike', 'bike', 54321]

List Concatenation and List Replication

>>> [4, 5, 6] + ['P', 'Q', 'R'] [4, 5, 6, 'P', 'Q', 'R'] >>> ['A', 'B', 'C'] * 4 ['A', 'B', 'C', 'A', 'B', 'C', 'A', 'B', 'C', 'A', 'B', 'C'] >>> list = [1, 2, 3] >>> list = list + ['X', 'Y', 'Z'] >>> list [1, 2, 3, 'X', 'Y', 'Z']

Removing Values from Lists

>>> list = ['truck', 'car', 'submarine', 'jet'] >>> del list[2] >>> list ['truck', 'car', 'jet'] >>> del list[2] >>> list ['truck', 'car']

Using for Loops with Lists for Traversal

>>> products = ['bag', 'rubber', 'knife', 'cooker'] >>> for i, product in enumerate(products): >>> print('Index <> in products is: <>'.format(str(i), product)) Index 0 in products is: bag Index 1 in products is: rubber Index 2 in products is: knife Index 3 in products is: cooker

Iterating through Multiple Lists with Zip()

>>> name = ['David', 'Mike', 'Tommy'] >>> age = [10, 31, 54] >>> for n, a in zip(name, age): >>> print('<> is <> years old'.format(n, a)) David is 10 years old Mike is 31 years old Tommy is 54 years old

The In and Not in Operators

>>> 'pen' in ['cap', 'owl', 'pen', 'rubber'] True >>> list = ['cap', 'owl', 'pen', 'rubber'] >>> 'truck' in list False >>> 'pen' not in list False >>> 'train' not in list True

Finding a Value in a List with the Index() Method

>>> list = ['notebook', 'pen', 'eraser', 'sharpener'] >>> list.index('pen') 1

Adding Values to Lists with the Append() and Insert() Methods

append()

>>> list = ['car', 'truck', 'bike'] >>> list.append('bicycle') >>> list ['car', 'truck', 'bike', 'bicycle']

insert()

>>> list = ['car', 'truck', 'bike'] >>> list.insert(1, 'bicycle') >>> list ['car', 'bicycle', 'truck', 'bike']

Removing Values from Lists with Remove()

>>> list = ['car', 'bike', 'submarine', 'jet'] >>> list.remove('bike') >>> list ['car', 'submarine', 'jet']

If a value appears multiple times in the list, only the first instance of the value will be removed.

Sorting the Values in a List with the Sort() Method

>>> list = [2, 3, 1] >>> list.sort() >>> list [1, 2, 3]

Dictionaries and Structuring Data

A Python dictionary is a collection of elements that are not in any particular order. A dictionary has a key: value pair, whereas other compound data types simply have value as an element.

The Keys(), Values(), and Items() Methods

• Traversing the values:

>>> book = >>> for v in book.values(): >>> print(v) red 160

• Traversing the keys:

>>> for k in book.keys(): >>> print(k) color price

• Traversing keys and values:

>>> for i in book.items(): >>> print(i) ('color', 'red') ('price', 160)

A for loop can iterate through the keys, values, or key-value pairs in a dictionary using the keys(), values(), and items() methods, respectively.

The Get() Method

Get() accepts two parameters: a key and a default value if the key isn't found.

>>> items = >>> 'There are <> tables.'.format(str(items.get('tables', 0))) 'There are 2 tables.' >>> 'There are <> computers.'.format(str(items.get('computers', 0))) 'There are 0 computers.'

Check Key’s Presence in Dictionary

>>> 'color' in book True

Sets

A set is an unordered collection of unique elements. Python sets are similar to mathematics sets, and allow all set related operations including union, intersection, and difference.

Creating a Set

You can generate sets by using curly braces <> and the built-in function set ():

>>> s = >>> s = set([2, 4, 6])

If you use curly braces <> to create an empty set, you'll get the data structure as a dictionary instead.

>>> s = <> >>> type(s)

All duplicate values are automatically removed by a set:

>>> s = >>> s

Adding to the Set

>>> a = >>> a.add(6) >>> a >>> set = >>> set.update([2, 3, 4, 5, 6]) >>> set

Removing from a Set

The remove() and discard() methods remove an element from the set; however remove() will throw a key error if the value isn't present.

>>> set = >>> set.remove(4) >>> set >>> set.remove(3) Traceback (most recent call last): File "", line 1, in KeyError: 3

You can also use discard():

>>> s = >>> s.discard(4) >>> s >>> s.discard(4)

Union of Multiple Sets

>>> s1 = >>> s2 = >>> s1.union(s2)

Intersection of Multiple Sets

>>> s1 = >>> s2 = >>> s3 = >>> s1.intersection(s2, s3)

Difference of Two Sets

>>> s1 = >>> s2 = >>> s1.difference(s2) >>> s2.difference(s1)

Symmetric Difference of Two Sets

>>> s1 = >>> s2 = >>> s1.symmetric_difference(s2)

itertools Module

When dealing with iterators, the itertools module offers a set of quick and memory-efficient tools (like lists or dictionaries).

Accumulate()

Using accumulate() returns the results of a function as an iterator:

import itertools import operator data = [1, 2, 3, 4, 5] result = itertools.accumulate(data, operator.mul) for each in result: print(each)

Output

1 2 6 24 120

The operator.mul() takes two numbers and multiplies them:

operator.mul(3, 5) 15 operator.mul(4, 3) 12 operator.mul(6, 3) 18 operator.mul(2, 5) 10

We can also use the method without any iterator:

import itertools data = [1, 2, 3, 4, 5, 6, 7] result = itertools.accumulate(data) for each in result: print(each)

Output

1 3 6 10 15 21 28

Combinations()

import itertools shapes = [1, 2, 3, 4, 5] combinations = itertools.combinations(shapes, 2) for combination in combinations: print(combination)

Output

(1, 2) (1, 3) (1, 4) (1, 5) (2, 3) (2, 4) (2, 5) (3, 4) (3, 5) (4, 5)

Combinations_with_Replacement()

import itertools shapes = [1, 2, 3, 4, 5] combinations = itertools.combinations_with_replacement(shapes, 2) for combination in combinations: print(combination)

Output

(1, 1) (1, 2) (1, 3) (1, 4) (1, 5) (2, 2) (2, 3) (2, 4) (2, 5) (3, 3) (3, 4) (3, 5) (4, 4) (4, 5) (5, 5)

Count()

A count takes the initial point and step size:

import itertools for i in itertools.count(1, 3): print(i) if i >= 15: break

Output

1 4 7 10 13 16

Cycle()

Here is an itertools.cycle(iterable):

import itertools arr = [1, 2, 3, 4, 5] c = 0 for itr in itertools.cycle(arr): if(c > 20): break print(itr) c += 1

Output

1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1 2 3 4 5 1