Plotting, GUI and Databases

 Plotting

Matplotlib is a Python library for data visualization. It helps you create charts, graphs, and plots to better understand and present data. 

You can use it to draw:

• Line charts
• Bar charts
• Pie charts
• Scatter plots
• Histograms

First, we have to import matplotlib.

import matplotlib.pyplot as plt

Here,

• matplotlib → main library
• pyplot → module that contains functions for creating plots

pyplot provides a state-based interface — it keeps track of the current figure and axes, so you can create and modify plots easily with simple function calls.

Commonly Used pyplot Functions:

Function	Description
plt.plot()	Draws line plots
plt.scatter()	Creates scatter plots
plt.bar()	Creates bar charts
plt.hist()	Plots histograms
plt.pie()	Creates pie charts
plt.title()	Adds a title to the plot
plt.xlabel() / plt.ylabel()	Labels axes
plt.legend()	Adds a legend
plt.grid()	Adds a grid
plt.show()	Displays the plot

1️⃣ Line Chart

A Line Chart is used to display data points connected by straight lines.
It shows trends or changes over a period of time or a continuous variable.

Syntax:

plt.plot(x, y, color='blue', linestyle='-', marker='o', label='Line')

Argument	Description
x	X-axis values
y	Y-axis values
color	Color of the line
linestyle	Style of the line ('-', '--', ':', '-.')
marker	Shape of points ('o', 's', '*', 'x')
label	Label for legend
linewidth	Thickness of line
alpha	Transparency level

2️⃣ Bar Chart

A Bar Chart represents data with rectangular bars where the height (or length) of each bar shows the value of the variable.
It is used for comparing different categories.

Syntax:

plt.bar(x, height, color='orange', width=0.5, label='Data')

Argument	Description
x	Categories or labels
height	Height of each bar
color	Color of bars
width	Thickness of bars
label	Label for legend
align	Align bars ('center' or 'edge')
alpha	Transparency of bars

3️⃣ Pie Chart

A Pie Chart is a circular chart divided into slices, where each slice represents a portion or percentage of the total.
It’s used to show proportional data.

Syntax:

plt.pie(sizes, labels=names, colors=colors, autopct='%1.1f%%', startangle=90, shadow=True)

Argument	Description
sizes	Values for each slice
labels	Names of slices
colors	List of colors for slices
autopct	Format for percentage labels
startangle	Rotation angle (in degrees)
shadow	Adds a shadow under the pie
explode	“Pull out” a slice for emphasis

4️⃣ Scatter Plot

A Scatter Plot uses dots to represent the values of two variables.
It helps to identify relationships or correlations between them.

Syntax:

plt.scatter(x, y, color='green', marker='x', s=80, alpha=0.7, label='Points')

Argument	Description
x	X-axis values
y	Y-axis values
color	Color of points
marker	Shape of points ('o', 's', 'x', '*', etc.)
s	Size of points
alpha	Transparency
label	Label for legend

5️⃣ Histogram

A Histogram displays the distribution of continuous data by grouping it into bins (ranges).
Each bar represents how many values fall into that range.

Syntax:

plt.hist(data, bins=5, color='purple', edgecolor='black', alpha=0.7)

Argument	Description
data	Input numeric data
bins	Number of intervals/groups
color	Bar color
edgecolor	Border color of bars
alpha	Transparency
orientation	'vertical' or 'horizontal'
rwidth	Width of bars (0–1)

Refer the below link for all plots:

plots

• A grid is a set of horizontal and vertical lines drawn across the plot background to make reading values easier. 

plt.grid(True)

• A legend is a box that explains what each line, color, or shape in your plot represents. 

plt.legend()

Why Do We Use Matplotlib?

Feature	Description
Visualizes Data	Converts raw data into easy-to-understand graphs
Customizable	You can change colors, styles, labels, and layouts
Works with NumPy & Pandas	Often used in data analysis
Multiple Plot Types	Line, bar, scatter, histogram, pie, etc.

GUI Programming

A Graphical User Interface (GUI) is a visual way for users to interact with software using buttons, text boxes, labels, menus, etc. instead of typing commands in the console.

In Python, the tkinter module is the standard GUI toolkit. It allows you to create windows, add widgets (like labels, buttons, text boxes), and handle user interactions.

Working Flow of Tkinter:

Step	Description
1. Import Module	Import everything from tkinter (or use import tkinter as tk).
2. Create Main Window	Create a main GUI window using Tk().
3. Add Widgets	Add GUI components like Labels, Buttons, Entries, etc.
4. Place Widgets	Use geometry managers (pack(), grid(), place()) to position them.
5. Define Events/Functions	Define functions for user actions (like button clicks).
6. Run Main Loop	Run the mainloop() — keeps the window open and listens for user events.

Tkinter Widgets:

Widget	Purpose
Label	Display text or images.
Entry	Accept single-line text input.
Button	Perform an action when clicked.
Text	Accept multi-line text input.
Checkbutton / Radiobutton	Choose options.
Frame	Container for grouping widgets.

Example:

from tkinter import *
from tkinter import messagebox

# Create main window
root = Tk()
root.title("Simple Widgets Example")
root.geometry("300x300")

# Label
label1 = Label(root, text="Enter your name:", font =("Times New Roman", 20))
label1.pack()

# Entry (for user input)
entry1 = Entry(root) # define Entry properly here
entry1.pack()

# Checkbutton
check_var = IntVar()
check1 = Checkbutton(root, text="I like Python", variable=check_var)
check1.pack()

# Radiobuttons
radio_var = StringVar(value="None")
radio1 = Radiobutton(root, text="Male", variable=radio_var, value="Male")
radio2 = Radiobutton(root, text="Female", variable=radio_var, value="Female")
radio1.pack()
radio2.pack()

# Function for button click
def show_data():
    name = entry1.get() #  gets text from Entry
    gender = radio_var.get()
    likes = "Yes" if check_var.get() == 1 else "No"
    messagebox.showinfo("Details", f"Name: {name}\nGender: {gender}\nLike Python: {likes}")

# Button
button1 = Button(root, text="Show Details", command=show_data)
button1.pack(pady=10)

root.mainloop()

Code after adding dialog box:

from tkinter import *

from tkinter import messagebox

# Create main window

root = Tk()

root.title("Simple Widgets Example")

root.geometry("300x300")

# Label

label1 = Label(root, text="Enter your name:", font =("Times New Roman", 20))

label1.pack()

# Entry (for user input)

entry1 = Entry(root) # define Entry properly here

entry1.pack()

# Checkbutton

check_var = IntVar()

check1 = Checkbutton(root, text="I like Python", variable=check_var)

check1.pack()

# Radiobuttons

radio_var = StringVar(value="None")

radio1 = Radiobutton(root, text="Male", variable=radio_var, value="Male")

radio2 = Radiobutton(root, text="Female", variable=radio_var, value="Female")

radio1.pack()

radio2.pack()

# Function for button click

def show_data():

    name = entry1.get() #  gets text from Entry

    gender = radio_var.get()

    likes = "Yes" if check_var.get() == 1 else "No"

    messagebox.showinfo("Details", f"Name: {name}\nGender: {gender}\nLike Python: {likes}")

    

    # ---------- Added Dialog Box Section ----------

    dialog = Toplevel(root)

    dialog.title("User Details")

    dialog.geometry("250x150")

    

    Label(dialog, text="User Details", font=("Times New Roman", 16, "bold")).pack(pady=5)

    Label(dialog, text=f"Name: {name}").pack(pady=2)

    Label(dialog, text=f"Gender: {gender}").pack(pady=2)

    Label(dialog, text=f"Likes Python: {likes}").pack(pady=2)

    

    Button(dialog, text="Close", command=dialog.destroy).pack(pady=10)

    # ----------------------------------------------

# Button

button1 = Button(root, text="Show Details", command=show_data)

button1.pack(pady=10)

root.mainloop()

Databases

1. Install the MySQL Connector

First, install MySQL on your device. After installation,You need to install a connector so that Python can talk to MySQL.

In your terminal or command prompt, type:

pip install mysql-connector-python

2. Import the Connector

In your Python file, import it:

import mysql.connector

3. Establish a Connection

Connect to your MySQL server using your database credentials:

mydb = mysql.connector.connect(

    host="localhost",        # Your host, usually localhost

    user="root",             # Your MySQL username

    password="your_password",# Your MySQL password

    database="testdb"        # Your database name

)

4. Create a Cursor

A cursor helps you execute SQL queries:

mycursor = mydb.cursor()

5. Create a Table

mycursor.execute("CREATE TABLE students (id INT AUTO_INCREMENT PRIMARY KEY, name VARCHAR(255), age INT)")

6. Insert Data

sql = "INSERT INTO students (name, age) VALUES (%s, %s)"

val = ("Swati", 22)

mycursor.execute(sql, val)

mydb.commit()   # Save the changes

print(mycursor.rowcount, "record inserted.")

7. Fetch Data

mycursor.execute("SELECT * FROM students")

result = mycursor.fetchall()

for row in result:

    print(row)

8. Close the Connection

Always close the connection when done:

mydb.close()

 

Example

import mysql.connector

# Connect to database

mydb = mysql.connector.connect(

    host="localhost",

    user="root",

    password="your_password",

    database="testdb"

)

# Create cursor

mycursor = mydb.cursor()

# Insert data

sql = "INSERT INTO students (name, age) VALUES (%s, %s)"

val = ("Swati", 22)

mycursor.execute(sql, val)

mydb.commit()

# Retrieve data

mycursor.execute("SELECT * FROM students")

for x in mycursor.fetchall():

    print(x)

# Close

mydb.close()