Python PyPlot

Python Tutorial @ Home
Introduction
Matplotlib and numpy
Installing NumPy and Matplotlib
Types of visualization
Baisc Visualization rules
Line plot / chart

Data visualization using pyplot 5

Matplotlib Line Chart

Line charts work out of the box with matplotlib. You can have multiple lines in a line chart, change color, change type of line, and much more.

Matplotlib is a Python module for plotting. Line charts are one of the many chart types it can create.

Line chart examples

Example:1

Simple line chart

First import matplotlib and NumPy, these are useful for charting.
You can use the plot(x,y) method to create a line chart.

The NumPy linspace function (sometimes called np.linspace ) is a tool in Python for creating numeric sequences. It’s somewhat similar to the NumPy arrange function, in that it creates sequences of evenly spaced numbers structured as a NumPy array.

Syntax:

numpy.linspace(start, stop, num = 50, endpoint = True, retstep = False, dtype = None)

Returns number spaces evenly w.r.t interval. Similar to arange but instead of step it uses sample number.
Parameters :

start : [optional] start of interval range. By default start = 0
stop: end of interval range
restep: If True, return (samples, step). By default restep = False
num : [int, optional] No. of samples to generate
dtype : type of output array

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-1, 1, 50)
print(x)
y = 2*x + 1

plt.plot(x, y)
plt.show()

Python PyPlot | rajeshshuklacatalyst.com

Example:2

Curved line

The plot() method also works for other types of line charts. It doesn’t need to be a straight line, y can have any type of values.

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-1, 1, 50)
y = 2**x + 1

plt.plot(x, y)  
plt.show()

Python PyPlot | rajeshshuklacatalyst.com

Example:3

Line with Labels

To know what you are looking at, you need metadata. Labels are a type of metadata. They show what the chart is about. The chart has an x label, y label, and title.

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-1, 1, 50)
y1 = 2*x + 1
y2 = 2**x + 1

plt.figure()
plt.plot(x, y1)  

plt.xlabel("I am x")
plt.ylabel("I am y")
plt.title("With Labels")

plt.show()

Python PyPlot | rajeshshuklacatalyst.com

Example:4

Multiple lines

More than one line can be in the plot. To add another line, just call the plot(x,y) function again. In the example below, we have two different values for y (y1,y2) that are plotted onto the chart.

import matplotlib.pyplot as plt
import numpy as np

x = np.linspace(-1, 1, 50)
y1 = 2*x + 1
y2 = 2**x + 1

plt.figure(num = 3, figsize=(8, 5))
plt.plot(x, y2)
plt.plot(x, y1, 
         color='red',   
         linewidth=1.0,  
         linestyle='--' 
        )

plt.show()

Python PyPlot | rajeshshuklacatalyst.com

Python Basic Programming Tutorial

Python Introduction     Getting started in Python Programming      Python propgramming fundamentals     Python Operators    Python If Condition     Python for loop    Python range construct      Python While loop    break and continue statements     Different looping techniques     Python List     Python String     Python Functions    Python Inbuilt Functions     Python Recursion     Using Python Library     Python Tuples     Python Dictionary     Python Sets     Python Strings     Python Exception Handling     Python Data File Handling

Visitor Counter

0183272