Plotting Graph by Keyboard Input using Python

Introduction to 2D Smooth Graph

Connecting line between two points (x₁, y₁) and (x₂, y₂) is known as a graph. A non-uniform cartesian co-ordinates points will generate a rigid line, which looks ugly. In Python, a rigid graph can be regenerated into a smooth graph by interpolating more points using SciPy module. SciPy (Scientific Python library) generates more sub-points based on the input array values to form a smooth curve. In this program, I have used input() function to get n number of points (x, y) from the user through keyboard (screenshot is given in the bottom) and store it to arrays. The co-ordinates points used in the program are (1, 2), (2, 5), (3, 3), (4, 6), (5, 7), (6, 2), (7, 10), (8, 5), (9, 6), and (10, 3).

Program Implementation

In this tutorial, I have used Python 3.5.2 (64-bit) software, and 7 modules: MatPlotLib 2.0.2, PyParsing 2.2.0, Python-DateUtil 2.6.1, PyTZ 2017.2, SetupTools 36.2.0, Cycler 0.10.0, SciPy 0.19.1, and NumPy-MKL 1.13.1 implemented in Windows 10 Enterprise (64-bit) operating system. The 8 modules are chosen based on the compatibility of Python version and OS bit.

Source Code

import scipy.interpolate as inter
import numpy as np
import matplotlib.pyplot as plt

p, h = list(), list()

print("Pulse vs Height Graph:-\n")
n = input("How many records? ")

print("\nEnter the pulse rate values: ")
for i in range(int(n)):
 pn = input()
 p.append(int(pn))
 x = np.array(p)

print("\nEnter the height values: ")
for i in range(int(n)):
 hn = input()
 h.append(int(hn))
 y = np.array(h)

print("\nPulse vs Height graph is generated!")

z = np.arange(x.min(), x.max(), 0.01)
s = inter.InterpolatedUnivariateSpline(x, y)

plt.plot (x, y, 'b.')
plt.plot (z, s(z), 'g-')
plt.xlabel('Pulse')
plt.ylabel('Height')
plt.title('Pulse vs Height Graph')
plt.show()

Command Prompt