Creating a line graph with Python and Tkinter's canvas

Python Tkinter Canvas and Graphics: Exercise-4 with Solution

Write a Python program that uses the Canvas widget to draw a line graph based on the provided data points using Tkinter.

Sample Solution:

Python Code:

import tkinter as tk

# Sample data points (x, y)
data_points = [(10, 20), (20, 50), (30, 35), (40, 90), (50, 60), (60, 110)]

class LineGraphApp:
    def __init__(self, root, data):
        self.root = root
        self.root.title("Line Graph")

        self.canvas = tk.Canvas(root, width=400, height=300, bg="white")
        self.canvas.pack()

        self.data = data

        self.draw_line_graph()

    def draw_line_graph(self):
        x_scale = 4  # Scale for x-axis
        y_scale = 2  # Scale for y-axis
        x_offset = 30
        y_offset = 250

        # Draw x and y axes
        self.canvas.create_line(x_offset, y_offset, x_offset + 360, y_offset, width=2)
        self.canvas.create_line(x_offset, y_offset, x_offset, y_offset - 250, width=2)

        # Draw data points and lines
        for i in range(len(self.data) - 1):
            x1, y1 = self.data[i]
            x2, y2 = self.data[i + 1]
            x1_scaled, y1_scaled = x1 * x_scale + x_offset, y_offset - y1 * y_scale
            x2_scaled, y2_scaled = x2 * x_scale + x_offset, y_offset - y2 * y_scale
            self.canvas.create_oval(x1_scaled - 3, y1_scaled - 3, x1_scaled + 3, y1_scaled + 3, fill="green")
            self.canvas.create_line(x1_scaled, y1_scaled, x2_scaled, y2_scaled, fill="blue", width=2)

if __name__ == "__main__":
    root = tk.Tk()
    app = LineGraphApp(root, data_points)
    root.mainloop()

Explanation:

In the exercise above -

• Import the Tkinter library (tkinter).
• Define a "LineGraphApp" class to manage the line graph application.
• The "draw_line_graph()" method draws a line graph based on the provided data points.
• Scale the x and y values to fit the canvas and apply appropriate offsets.
• The x and y axes are drawn as well as data points and lines connecting them.
• Create a sample list of data points (data_points) to draw a line graph.
• The program sets up a Tkinter window with a canvas and calls the "draw_line_graph()" method to display the line graph.
• The main event loop, root.mainloop(), starts the Tkinter application.

Output:

Flowchart:

Python Code Editor:

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