Python is a high-level programming language, in layman's language, it is closer to human understanding(English like) than it is to machines. Python is an interpreted language and a general purpose programming language.
A brief history of python
Python is programming language that came into life in the 1980s and was developed by Guido van Rossum at Centrum Wiskunde & Informatica (CWI) in the Netherlands, with the ideology of it being a successor to the ABC programming language.
Since then python has evolved through several versions to the latest version python 3.10 (as of the time of writing this article) with a first release date of 4 October, 2021
Python 2.0, released 16 October 2000, with new features including a cycle-detecting garbage collector for memory management and support for Unicode.
Python 3.0, released on 3 December 2008.With this version there was massive revision that it was not backward compatible with previous python versions.
Before we get our hands dirty, let's set some rules of engagement, shall we!
Syntax in Python
Python has a very simple and user friendly syntax, that you'll find simple and easy to grasp.
Some include:
Indentation in python is crucial, it can break your code!
Python is case sensitive, State and state are different
All variables should start with a lowercase letter
classes begin with capital letters
The standard is to actually use English names in programming
Identifiers (names you define for variables, types, functions, and labels) should not be keywords in python and start with a symbol or number.
For more on style and best practices in python check out on PEP-8
Installing python
Python Basics
Base types
- int (integer)
value = 76
- float
value = 56.21
- bool (boolean)
is_blue = True
- str (string)
message = "Hello world!"
Backslash is used for escaping characters.
e.g
- \' - Single quote
- \b - backspace
- \n - new line
- \r - carriage return
- \t - tab
message = " \t Sammy\'s cat ran away\nand into the bush it went.\n"
# print - an inbuilt function to print an output
print(message)
# output
# Sammy's cat ran away
# and into the bush it went.
Multiline strings
message = """ Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut
aliquip ex ea commodo consequat."""
Sequence types
- list
Lists are modifiable and can hold values of different types.
list_country = ["Russia", "South Africa", "Japan", "Peru"]
random_list = ["x", 3.14, 4, False, "No way"]
- tuple
Tuples cannot be modified once created. They are immutable.
coordinates = (33.56, 4.56, 21.89)
- range
Is a function returning a sequence of numbers, starts from 0 and increments by 1 by default.
Format: range(start, stop, step)
for x in range(0,10,2):
print(x)
Mapping types
Dictionary
Is a collection of data that is stored in key-value pair, key is unique
e.g "Laptop" is the key and "Mac book" the value.
backpack = {"Laptop":"Mac book", "Headphones": "Sony", "Hard drive": "SSD"}
Set types
- set
A set is an unordered collection that is mutable, iterable and has unique elements.
fruits = {"apple", "mango", "orange"}
2.frozen-set
Freezes the elements, making them unchangeable.
fruits = ({"apple, "mango", "orange"})
Conversions
Change a value of one data type to another.
""" 1.str to int"""
int("10") #output: 10
""" 2. float to int"""
int(10.34) #output: 10
""" 3. any data type to str"""
str(10.10) #output: "10.1"
str(3==3) #output: "True"
""" 4. character to ASCII code """
ord('*') #output: 42
""" 5. string to list"""
message = "Hello world!"
message_list = list(message)
# print- print output
print(message_list)
# output
# ['H', 'e', 'l', 'l', 'o', ' ', 'w', 'o', 'r', 'l', 'd', '!']
""" 6. dictionary to list """
day = {"day":14, "month": "Feb", "year": 2022}
# create a list with list compression
generated_list = [(x, y) for x, y in day.items()]
# print - print output
print(generated_list)
# output
# [('day', 14), ('month', 'Feb'), ('year', 2022)]
""" 7. list to string """
word_list = ["The", "new", "version", "of", "slack", "is", "amazing"]
word_str = " ".join(word_list)
print(word_str)
# output
# The new version of slack is amazing
""" 8. list to set """
number_list = [34, 45, 67 ,87]
number_set = set(number_list)
print(number_set)
# output
# {34, 67, 45, 87}
""" 9. list to dictionary """
day_list = [('day', 14), ('month', 'Feb'), ('year', 2022)]
day_dict = dict(day_list)
print(day_dict)
# output
# {"day":14, "month": "Feb", "year": 2022}
Working with Strings
There are several ways in which strings can be manipulated.
print("Hello")
# output
# Hello
print("Hello", "world", "!")
# output
# Hello world !
print("Hello", "world", sep="-")
# output
# Hello-world
print("Hello") # for every print, output is set to a new line
print("world")
# output
# Hello
# World
print("Hello", "world", sep="-", end="!")
# output
# Hello-world!
print("Hello", end=" ") # without new line
print("World")
# output
# Hello world
String Concatenation
String concatenation is the operation of joining character strings end-to-end.(wikipedia)
first_name = "John"
middle_name = "Magarita"
last_name = "Omondi"
print(first_name + " " + middle_name + " " + last_name)
# output
# John Magarita Omondi
String formatting
first_name = "John"
middle_name = "Magarita"
last_name = "Omondi"
salary = 50000
print("{0} {1} earns a salary of ${2}".format(first_name, middle_name, salary))
# output
# John Magarita earns a salary of $50000
With knowing the basics of python, you can write simple command line programs
for example:
Simple mad-libs generator program
""" A simple word game that takes user input based on the word type and
inserting in to a paragraph """
noun1 = input("Enter a noun(Plural): ")
place = input("Enter a place: ")
noun2 = input("Enter a noun: ")
noun3 = input("Enter a noun(Plural): ")
adjective1 = input("Enter an Adjective: ")
verb1 = input("Enter a verb: ")
verb2 = input("Enter a verb: ")
number = input("Enter a number: ")
adjective2 = input("Enter an Adjective: ")
body_part = input("Enter a body part: ")
verb3 = input("Enter a verb: ")
mad_lib = """Two {0}, both alike in dignity,
In fair {1} where we lay our scene,
From ancient {2} break to new mutiny,
Where civil blood makes civil hands unclean.
From forth the fatal loins of these two foes
A pair of star-cross`d {3} take their life;
Whole misadventured piteous overthrows
Do with their {4} bury their parents` strife.
The fearful passage of their {5} love,
And the continuance of their parents` rage,
Which, but their children`s end, nought could {6},
Is now the {7} hours` traffic of our stage;
The which if you with {8} {9} attend,
What here shall {10}, our toil shall strive to mend. """.format(noun1, place, noun2, noun3, adjective1, verb1, verb2,number, adjective2,body_part, verb3)
print("\n====Mad Lib (Romeo and Juliet: Prologue Ad-lib) ====\n")
print(mad_lib)
Conclusion
Python is an amazing multi-purpose programming language that can be used in almost all fields in technology, from AI to scripting and data science. The best part is, it is fun to learn and user-friendly.
Happy coding!
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