Build a Calculator in Python Using Lambda & Tkinter

Creating a calculator is a great way to learn about Python functions, GUI programming, and event handling. In this tutorial, we’ll build a simple calculator using lambda functions for operations and Tkinter for the user interface.

What You will Learn

How to use lambda functions for basic operations
How to build a Tkinter GUI
How to wire up buttons with actions dynamically

Prerequisites

Python 3.x installed
Basic knowledge of Python functions and Tkinter

You can install Tkinter (if not already installed) using:

pip install tk

Note: Tkinter comes pre-installed with most Python distributions.

🔣 Step-by-Step: Create a Lambda-Based Calculator

✅ Step 1: Import Tkinter

import tkinter as tk
from functools import partial

✅ Step 2: Define Operations Using Lambda

operations = {
    '+': lambda x, y: float(x) + float(y),
    '-': lambda x, y: float(x) - float(y),
    '*': lambda x, y: float(x) * float(y),
    '/': lambda x, y: float(x) / float(y) if float(y) != 0 else "Error"
}

✅ Step 3: Create the GUI Window

root = tk.Tk()
root.title("Lambda Calculator")
root.geometry("300x300")

✅ Step 4: Create Input Fields and Result Display

entry1 = tk.Entry(root, width=10)
entry1.grid(row=0, column=0, padx=10, pady=10)

entry2 = tk.Entry(root, width=10)
entry2.grid(row=0, column=1, padx=10, pady=10)

result_label = tk.Label(root, text="Result: ")
result_label.grid(row=1, column=0, columnspan=2)

✅ Step 5: Define a Generic Operation Handler

def calculate(op):
    try:
        val1 = entry1.get()
        val2 = entry2.get()
        result = operations[op](val1, val2)
        result_label.config(text=f"Result: {result}")
    except Exception as e:
        result_label.config(text="Error")

✅ Step 6: Create Buttons for Operations

row = 2
col = 0

for symbol in operations:
    action = partial(calculate, symbol)
    tk.Button(root, text=symbol, width=5, command=action).grid(row=row, column=col, padx=5, pady=5)
    col += 1

✅ Step 7: Run the Application

root.mainloop()

Full Working Code

Here’s the full code for your reference:

import tkinter as tk
from functools import partial

# Define lambda operations
operations = {
    '+': lambda x, y: float(x) + float(y),
    '-': lambda x, y: float(x) - float(y),
    '*': lambda x, y: float(x) * float(y),
    '/': lambda x, y: float(x) / float(y) if float(y) != 0 else "Error"
}

# Create the window
root = tk.Tk()
root.title("Lambda Calculator")
root.geometry("300x300")

# Entry widgets
entry1 = tk.Entry(root, width=10)
entry1.grid(row=0, column=0, padx=10, pady=10)

entry2 = tk.Entry(root, width=10)
entry2.grid(row=0, column=1, padx=10, pady=10)

# Result label
result_label = tk.Label(root, text="Result: ")
result_label.grid(row=1, column=0, columnspan=2)

# Calculation function
def calculate(op):
    try:
        val1 = entry1.get()
        val2 = entry2.get()
        result = operations[op](val1, val2)
        result_label.config(text=f"Result: {result}")
    except Exception:
        result_label.config(text="Error")

# Buttons for operations
row = 2
col = 0
for symbol in operations:
    action = partial(calculate, symbol)
    tk.Button(root, text=symbol, width=5, command=action).grid(row=row, column=col, padx=5, pady=5)
    col += 1

# Run the app
root.mainloop()

Summary

Lambda functions let us define concise, anonymous operations.
Tkinter helps us build user interfaces with minimal code.
This calculator is fully functional and can be expanded to support more features like clearing fields or advanced operations.

Would you like to watch video explanation to create a calculator using python Lambda ? watch video below: