Day 7 of My Data Analytics Journey

This content originally appeared on DEV Community and was authored by Ramya .C

Mastering Python Lists & Dictionaries

Today marks the 7th day of my Data Analytics learning journey. I focused on Python’s core data structures like Lists and Dictionaries. Below is a quick breakdown of what I learned with definitions and example programs for each concept:

Python Lists

What is a List?

A list is a collection of items that are ordered, mutable, and can contain duplicates.

Homogeneous & Heterogeneous Lists:

• Homogeneous list – All elements are of the same type

numbers = [1, 2, 3, 4]

• Heterogeneous list – Elements of different types

mixed = [1, "Hello", 3.14, True]

Common List Operations:

1. Add Elements:

fruits = ["apple", "banana"]
fruits.append("cherry")     # ['apple', 'banana', 'cherry']
fruits.insert(1, "mango")   # ['apple', 'mango', 'banana', 'cherry']

2. Update Elements:

fruits[0] = "grape"         # ['grape', 'mango', 'banana', 'cherry']

3. Remove Elements:

fruits.remove("banana")     # ['grape', 'mango', 'cherry']
fruits.pop()                # removes last element

4. Looping:

for fruit in fruits:
    print(fruit)

5. Nested List:

nested = [[1, 2], [3, 4]]
print(nested[1][0])  # Output: 3

6. Slicing:

numbers = [10, 20, 30, 40, 50]
print(numbers[1:4])  # [20, 30, 40]

7. Reverse:

numbers.reverse()
print(numbers)  # [50, 40, 30, 20, 10]

Dictionary

What is a Dictionary?

A dictionary is a key-value pair data structure.

Example:

student = {"name": "Ramya", "age": 21, "course": "Data Analytics"}
print(student["name"])  # Output: Ramya

Today’s Tasks

1. Find Type of Variable:

x = 5
print(type(x))  # <class 'int'>

2. Find Range:

for i in range(1, 6):
    print(i)  # 1 to 5

3. Step in Range:

for i in range(0, 10, 2):
    print(i)  # 0, 2, 4, 6, 8

4. Push (Add element to list):

stack = []
stack.append(10)
stack.append(20)
print(stack)  # [10, 20]

5. Reverse List:

nums = [1, 2, 3, 4]
print(list(reversed(nums)))  # [4, 3, 2, 1]

6. Find Elements Less Than 5:

numbers = [1, 6, 3, 7, 4]
less_than_5 = [n for n in numbers if n < 5]
print(less_than_5)  # [1, 3, 4]

7. List Comprehension:

squares = [x**2 for x in range(1, 6)]
print(squares)  # [1, 4, 9, 16, 25]

Hashing in Python

What is Hashing?

Hashing is converting a value into a fixed-size integer using a hash function.

Example:

print(hash("Ramya"))  # Outputs an integer (hash value)

Today I got hands-on experience with:

• Lists (add, update, delete, loop, slice, reverse)
• Dictionaries
• Concepts like type(), range(), step, push, list comprehension, and hashing

I’m one step closer to becoming a Data Analyst!

This content originally appeared on DEV Community and was authored by Ramya .C