🧮 Building a Modern Statistics Calculator in Python with Tkinter

Source: Dev.to

Overview

Python is often praised for its data‑science ecosystem, but you don’t always need Pandas or NumPy to build something useful.

In this post we’ll build StatMate – a clean, modern desktop statistics calculator using:

• 🪟 Tkinter – Python’s standard GUI library
• 🎨 sv‑ttk – modern theming for Tkinter
• 📊 statistics – Python’s built‑in statistics module

By the end you’ll have a polished GUI app that calculates:

• Mean
• Median
• Mode
• Variance
• Standard Deviation
• Min / Max

…with real‑time input validation and configurable decimal precision.

✨ Features

• Modern light theme using sv‑ttk
• Real‑time input validation
• Placeholder‑text UX
• Adjustable decimal precision
• Clean status‑bar feedback
• Graceful error handling

📦 Requirements

Only one external dependency is needed:

pip install sv-ttk

Everything else comes from Python’s standard library.

🧠 Design Overview

The app is structured into logical sections:

1. Helpers – status updates, formatting, calculation driver
2. Validation – regex‑based numeric input filtering
3. Statistics Logic – uses the statistics module
4. UI Layout – cards, labels, buttons, and result panel
5. UX Enhancements – placeholder text, status bar, precision control

🧮 How the Calculation Works

The user enters numbers as a comma‑separated list, e.g.:

1, 2, 3, 4, 5

The app then:

1. Parses and sanitises the input
2. Converts values to float
3. Computes statistics safely
4. Formats output based on the selected precision

Edge cases (e.g., no unique mode or a single value) are handled gracefully.

🧑‍💻 Full Source Code

import tkinter as tk
from tkinter import ttk, messagebox
import sv_ttk
import statistics
import re

# =========================
# Helpers
# =========================
def set_status(msg):
    status_var.set(msg)
    root.update_idletasks()

def fmt(value):
    try:
        p = precision_var.get()
        return f"{value:.{p}f}"
    except Exception:
        return str(value)

def calculate_stats():
    raw_input = numbers_entry.get()
    if raw_input.strip() == 'e.g., 1, 2, 3, 4':
        messagebox.showerror("Invalid Input", "Please enter a valid list of numbers.")
        return
    try:
        numbers = [float(x.strip()) for x in raw_input.split(",") if x.strip() != ""]
        if not numbers:
            raise ValueError

        mean_val = statistics.mean(numbers)
        median_val = statistics.median(numbers)
        try:
            mode_val = statistics.mode(numbers)
        except statistics.StatisticsError:
            mode_val = "No unique mode"
        variance_val = statistics.variance(numbers) if len(numbers) > 1 else 0
        stdev_val = statistics.stdev(numbers) if len(numbers) > 1 else 0

        result_var.set(
            f"📊 Mean: {fmt(mean_val)}\n"
            f"📌 Median: {fmt(median_val)}\n"
            f"🎯 Mode: {mode_val}\n"
            f"📈 Variance: {fmt(variance_val)}\n"
            f"📉 Std. Dev.: {fmt(stdev_val)}\n"
            f"🔽 Min: {fmt(min(numbers))}\n"
            f"🔼 Max: {fmt(max(numbers))}"
        )
        set_status("✅ Statistics calculated successfully")
    except ValueError:
        messagebox.showerror("Invalid Input", "Please enter a valid list of numbers.")

def validate_input(new_value):
    if new_value == '' or new_value == 'e.g., 1, 2, 3, 4':
        return True
    return re.match(r'^[0-9.,\s-]*$', new_value) is not None

# =========================
# App Setup
# =========================
root = tk.Tk()
root.title("StatMate - Full Statistics Tool")
root.geometry("950x650")
root.minsize(950, 650)
sv_ttk.set_theme("light")

precision_var = tk.IntVar(value=4)
status_var = tk.StringVar(value="Ready")

ttk.Label(root, textvariable=status_var, anchor="w",
          font=("Segoe UI", 10), padding=(10, 5)
).pack(side="bottom", fill="x")

main_frame = ttk.Frame(root, padding=20)
main_frame.pack(expand=True, fill="both")

ttk.Label(main_frame, text="StatMate",
          font=("Segoe UI", 28, "bold")
).pack(anchor="w")

ttk.Label(main_frame, text="Full Statistics Calculator",
          font=("Segoe UI", 14), foreground="#555"
).pack(anchor="w", pady=(0, 20))

input_card = ttk.LabelFrame(main_frame, text="Input Numbers & Precision", padding=20)
input_card.pack(fill="x", pady=(0, 20))

input_row = ttk.Frame(input_card)
input_row.pack(fill="x")

def on_entry_click(event):
    if numbers_entry.get() == 'e.g., 1, 2, 3, 4':
        numbers_entry.delete(0, "end")
        numbers_entry.config(fg='black')

def on_focusout(event):
    if numbers_entry.get() == '':
        numbers_entry.insert(0, 'e.g., 1, 2, 3, 4')
        numbers_entry.config(fg='grey')

ttk.Label(input_row, text="Numbers:").grid(row=0, column=0)
numbers_entry = tk.Entry(input_row, font=("Segoe UI", 14), width=40, fg='grey')
numbers_entry.insert(0, 'e.g., 1, 2, 3, 4')
numbers_entry.bind('', on_entry_click)
numbers_entry.bind('', on_focusout)
numbers_entry.grid(row=0, column=1, padx=(5, 20))

vcmd = (root.register(validate_input), '%P')
numbers_entry.config(validate='key', validatecommand=vcmd)

ttk.Label(input_row, text="Decimal Precision:").grid(row=0, column=2)
ttk.Spinbox(input_row, from_=0, to=10,
            textvariable=precision_var, width=5
).grid(row=0, column=3, padx=(5, 0))

ttk.Button(main_frame, text="📊 Calculate Statistics",
           command=calculate_stats,
           style="Accent.TButton"
).pack(pady=20, ipadx=10, ipady=10)

result_card = ttk.LabelFrame(main_frame, text="Results", padding=20)
result_card.pack(fill="both", expand=True)

result_var = tk.StringVar(value="—")
tk.Label(result_card, textvariable=result_var,
         font=("Segoe UI", 16, "bold"),
         justify="left", anchor="nw",
         bd=2, relief="groove", padx=10, pady=10
).pack(fill="both", expand=True)

root.mainloop()

🚀 Possible Improvements

• Export results to CSV
• Add histogram visualization
• Dark‑mode toggle
• Keyboard shortcuts
• Save / load datasets

🎯 Final Thoughts

Tkinter doesn’t have to look outdated. With a bit of structure, validation, and modern theming, you can deliver a sleek, functional statistics tool that runs anywhere Python does. Happy coding!

If you enjoyed this project, consider extending it—or turning it into a reusable statistics toolkit.

Happy building! 🧠📊