Distributed ledger concept in Blockchain / Solidity - Mini Project: Build & Apply

Distributed Ledger Concept

📖 Scenario: Imagine you want to keep a shared list of transactions that multiple friends can see and agree on. This shared list is called a distributed ledger. Each friend adds their transactions, and everyone can check the list to make sure it is correct.

🎯 Goal: You will build a simple distributed ledger using a list of dictionaries. Each dictionary will represent a transaction with a sender, receiver, and amount. You will add transactions, set a minimum amount to record, and then print the filtered transactions.

📋 What You'll Learn

Create a list called ledger with 3 specific transactions

Create a variable called min_amount set to 50

Use a list comprehension to create filtered_ledger with transactions having amount greater than or equal to min_amount

Print the filtered_ledger list

💡 Why This Matters

🌍 Real World

Distributed ledgers are used in blockchain to keep a shared, secure record of transactions that many people can trust without a central authority.

💼 Career

Understanding how to manage and filter transaction data is important for blockchain developers, data analysts, and software engineers working with decentralized systems.

1

Create the initial ledger with transactions

Create a list called ledger with these exact transactions as dictionaries:
{'sender': 'Alice', 'receiver': 'Bob', 'amount': 100}, {'sender': 'Bob', 'receiver': 'Charlie', 'amount': 30}, and {'sender': 'Charlie', 'receiver': 'Alice', 'amount': 70}.

Blockchain / Solidity

# Create the ledger list with 3 transactions
# Your code here

Need a hint?

Use a list with three dictionaries. Each dictionary has keys 'sender', 'receiver', and 'amount'.

2

Set the minimum amount to record

Create a variable called min_amount and set it to 50.

Blockchain / Solidity

ledger = [
    {'sender': 'Alice', 'receiver': 'Bob', 'amount': 100},
    {'sender': 'Bob', 'receiver': 'Charlie', 'amount': 30},
    {'sender': 'Charlie', 'receiver': 'Alice', 'amount': 70}
]
# Set min_amount to 50
# Your code here

Need a hint?

Just create a variable named min_amount and assign the number 50.

3

Filter transactions by minimum amount

Use a list comprehension to create a new list called filtered_ledger that includes only transactions from ledger where the amount is greater than or equal to min_amount.

Blockchain / Solidity

ledger = [
    {'sender': 'Alice', 'receiver': 'Bob', 'amount': 100},
    {'sender': 'Bob', 'receiver': 'Charlie', 'amount': 30},
    {'sender': 'Charlie', 'receiver': 'Alice', 'amount': 70}
]
min_amount = 50
# Create filtered_ledger with transactions having amount >= min_amount
# Your code here

Need a hint?

Use a list comprehension with for tx in ledger and an if condition checking tx['amount'] >= min_amount.

4

Print the filtered ledger

Write a print statement to display the filtered_ledger list.

Blockchain / Solidity

ledger = [
    {'sender': 'Alice', 'receiver': 'Bob', 'amount': 100},
    {'sender': 'Bob', 'receiver': 'Charlie', 'amount': 30},
    {'sender': 'Charlie', 'receiver': 'Alice', 'amount': 70}
]
min_amount = 50
filtered_ledger = [tx for tx in ledger if tx['amount'] >= min_amount]
# Print the filtered_ledger list
# Your code here

Need a hint?

Use print(filtered_ledger) to show the filtered transactions.