Python Programming Glossary Key Words Explained Simply

# The five types you will use every day
name = "Ankit"          # str
age = 28                # int
score = 91.5            # float
is_active = True        # bool
skills = ["python", "sql"]   # list

# The two collection types you will also use a lot
location = {"city": "Delhi", "pin": "110092"}   # dict
unique_ids = {101, 102, 103}                     # set

# None means "no value yet"
selected = None

# Check a type
type(age)          # <class 'int'>
type(score)        # <class 'float'>
isinstance(age, int)   # True

# Convert between types
int("42")          # 42
str(42)            # "42"
float(3)           # 3.0
list("abc")        # ['a', 'b', 'c']

# Strings vs numbers
"5" + "5"          # "55"   (concatenation)
5 + 5              # 10     (addition)
int("5") + 5       # 10

# if / elif / else
score = 82
if score >= 90:
    grade = "A"
elif score >= 75:
    grade = "B"
else:
    grade = "C"
print(grade)      # B

# for loop
for n in [1, 2, 3, 4, 5]:
    if n == 3:
        continue          # skip 3
    if n == 5:
        break             # stop at 5
    print(n)              # 1, 2, 4

# while loop
count = 0
while count < 3:
    print("tick", count)
    count += 1

# A plain function
def add(a, b):
    return a + b

print(add(2, 3))      # 5

# Default arguments
def greet(name, msg="Hello"):
    return f"{msg}, {name}!"

print(greet("Ankit"))            # Hello, Ankit!
print(greet("Ankit", "Hi"))      # Hi, Ankit!

# *args and **kwargs
def total(*nums, **options):
    print(nums)       # (1, 2, 3)
    print(options)    # {'currency': 'INR'}
    return sum(nums)

total(1, 2, 3, currency="INR")

# lambda — a tiny function
double = lambda x: x * 2
print(double(5))      # 10

class Dog:
    def __init__(self, name, age):
        self.name = name        # attribute
        self.age = age          # attribute

    def bark(self):             # method
        return f"{self.name} says woof"

d = Dog("Rex", 3)               # instance
print(d.bark())                 # Rex says woof
print(d.name)                   # Rex

# Inheritance
class Puppy(Dog):
    def bark(self):
        return f"{self.name} says yip"

p = Puppy("Milo", 1)
print(p.bark())                 # Milo says yip

# Handle a common error
try:
    value = int("abc")
except ValueError:
    value = 0

print(value)                    # 0

# Raise your own
def set_age(age):
    if age < 0:
        raise ValueError("age cannot be negative")
    return age

try:
    set_age(-1)
except ValueError as e:
    print("Caught:", e)

# finally always runs
try:
    print("working")
finally:
    print("cleanup")

# Variables and types
x = 10
name = "Ankit"
flag = True

# Lists, dicts, sets
nums = [1, 2, 3]
info = {"name": "Ankit", "age": 28}
unique = {1, 2, 2, 3}        # {1, 2, 3}

# Conditionals
if x > 5:
    print("big")
else:
    print("small")

# Loops
for n in nums:
    print(n)

# Functions
def add(a, b=0):
    return a + b

# Classes
class Point:
    def __init__(self, x, y):
        self.x = x
        self.y = y

# Errors
try:
    result = 1 / 0
except ZeroDivisionError:
    result = None

# Comprehensions
squares = [n*n for n in range(5)]   # [0,1,4,9,16]

# F-strings
print(f"{name} is {28} years old")

Glossary terms to master before your first project:

Basics
☐ variable        ☐ type           ☐ int / float
☐ str             ☐ bool           ☐ None
☐ list            ☐ tuple          ☐ dict
☐ set

Flow
☐ if / elif / else
☐ for             ☐ while
☐ break           ☐ continue
☐ range()

Functions
☐ def             ☐ return
☐ parameter       ☐ argument
☐ *args           ☐ **kwargs
☐ lambda

Classes
☐ class           ☐ object
☐ __init__        ☐ self
☐ attribute       ☐ method
☐ inheritance

Errors
☐ try / except
☐ raise
☐ Exception

Comprehensions
☐ list comprehension
☐ dict comprehension

Tick each one once you have written code using it.