Python PyLab Module
In order to complete certain tasks, we are required to make use of graphs such as line charts, bar graphs, and so on. There are many reasons for this, including the fact that graphs are simple and self-explanatory, that they can make a task more interactive, that they can pass on information in a very interesting way, and so on. Because of this, the process of drawing a graph or chart is an integral and extremely crucial component of many functions. In the world of programming, graphs and charts play a very significant part, and it is strongly recommended that programmers incorporate graphs into their work whenever possible. As a result, it is essential for us to be familiar with the process of plotting graphs based on the output of a computer programme. It is generally agreed that MATLAB is the best programme for plotting graphs and charts; however, not everyone has access to MATLAB and therefore cannot use it for this purpose. We have many interactive modules available to us in Python, which gives us the ability to plot graphs and charts in the output; however, in this section, we will discuss the module, which gives us a namespace that is comparable to that of MATLAB by importing functions. In this guide, we will go through the Python PyLab Module, and then we will learn how to plot graphs and charts in the output by utilising the methods that come with this module in a plotting programme.
programme.
PyLab Module in Python
PyLab is a package for the Python programming language that gives us access to a namespace in Python that is quite comparable to the interface of MATLAB. This is accomplished by importing the relevant functions from the Python Numpy and Matplotlib Modules. Matplotlib Module provides functions that help us create visualisations of data, whereas Numpy Module provides efficient numerical vector calculation functions that are based on underlying C and Fortran binary libraries. If we talk about the role that these modules play in the PyLab package, we can say that the Numpy Module and the Matplotlib Module complement one another. In this part, we will learn about the PyLab Module, and then we will plot some fundamental graphs and charts by making use of the components and functions that are made available to us by this module.
us.
PyLab Module: Introduction
PyLab Module is an associated module with the Matplotlib Module of Python. As such, it is installed concurrently with Matplotlib Module if any of these two modules are added to a system. It is also possible to describe PyLab as the object-oriented charting library of Python’s Matplotlib Module, which has a procedural interface known as PyLab. PyLab is a persuasive module for us because of its cumbersome import of the functions provided by the NumPy Module and the matplotlib.pyplot package in a single namespace to give us with a MATLAB-like environment.
namespace.
PyLab Module: Installation
The installation of the Matplotlib package includes the installation of the PyLab Module as well. This is something that we have previously gone through. Nevertheless, if we wish to use this module in a Python application, we need to ensure that the Matplotlib Module is installed on our computer. This is a prerequisite for using the module. In the event that Matplotlib is not already installed on the machine, we may use the following pip installer command in the command prompt terminal shell to install the Matplotlib Module in order to acquire the PyLab Module with
it:
-
pip install matplotlib
In addition to this, we have also covered the fact that the Numpy Module’s mathematical and vector operation functions are used by the PyLab Module. Because of this, we need to check if the Numpy Module is also present in our computer system. If the Numpy Module is not already installed, then we may use the following command to install it from the command line.
terminal:
-
pip install numpy
After the successful installation of the necessary libraries for the PyLab Module, we are now able to utilise the PyLab Module inside the Python applications in order to produce graphs and charts based on their data.
functions.
PyLab Module: Implementation
In this section, we will make use of the methods provided by the PyLab Module to plot basic graphs and curves by including them inside of a Python programme in order to better comprehend how their functionality is implemented. First, we will go over the fundamentals of plotting curves, and then we will go on to more complex functions in order to make the graphs and curves that we have produced seem better.
interactive.
Basic plotting with PyLab Module:
Using the PyLab Module in a Python programme needs the use of a plot command, and this command accepts a pair of arrays or sequences that have the same length as its argument. Plotting curves in Python requires the use of a plot command. Let’s look at an example programme to have a better understanding of its implementation. Example:
Have a look at the following Python programme, which will serve as the basis for the plotting of a simple curve in the
output:
-
# Importing from Numpy
-
from numpy
import
*
-
# Importing from PyLab
-
from pylab
import
*
-
# X-axis of the curve
-
a = linspace(-
4
,
2
,
6
)
-
# Y-axis of the curve
-
b = a**
2
-
# Plotting the curve with x and y-axis
-
plot(a, b)
-
# Showing curve in the output
-
show()
Output:
The explanation for this is 
.
In order to utilise the functions from the Numpy and PyLab Modules in the programme for plotting a curve in the output, we have first imported all of the functions from both modules. Following that, the axes that correspond to the curve in the a and b variables, respectively, have been specified as the X and Y axes. After that, we made use of the plot() method by passing it the variables a and b as its parameters. At the end, we plotted a curve, and in order to display it in the output, we made use of the show() method.
Since the output shows the curve being plotted with points on the X and Y axes, we can deduce that the ‘a’ and ‘b’ variables that we declared on the inside are responsible for this behaviour.
respectively.
Advance Plotting with PyLab Module:
1. When plotting more interactive curves using the PyLab Module, in addition to the x and y variable inputs that we are supplying within it, we can also utilise some of the other variables that are available in the plot() method. If we want the plot() method to output symbol lines rather than the straight line in the curves, we need to give extra text parameters within the function. This may be comprehended by the implementation of the extra parameter in the following sample programme: Example 2:
Have a look at the following Python programme, which will plot a curve including symbols in the output using the PyLab.
Module:
-
# Importing from Numpy
-
from numpy
import
*
-
# Importing from PyLab
-
from pylab
import
*
-
# X-axis of the curve
-
a = linspace(-
4
,
8
,
32
)
-
# Y-axis of the curve
-
b = a **
3
-
# Plotting the curve with a and b variable
-
plot(a, b,
‘^’
)
-
# Showing curve in the output
-
show()
Output:
Explanation: 
Related:
We have created the ‘a’ and ‘b’ variables for the X-axis and Y-axis of the curve, respectively, in the programme after first importing functions from both Numpy and PyLab Module. These functions were used to create the curve. After that, we used the plot() function, and inside the plot function, we provided an additional argument of the ” symbol with the a & b variable so that the curve would be represented by a symbol rather than a simple straight line. This allowed us to display the curve as a symbol rather than as a straight line.
In the output, we can see that the curve is shown with the points on the X and Y axes. This is because we have declared the ‘a’ and ‘b’ variables, respectively, within the function, and the curve is represented by the symbol ” rather than a straight line.
If we want to print a symbol line in the plot() method rather than a straight line, we may use the following set of symbols as the parameter. If we want to print a symbol line in the plot() function, we can use the following set of symbols.
curve:
| Symbols | _, |, p, H, h, 4, 3, 2, 1, d, D, x, +, s, <, >, v, ^, o, ., ,, -, -., –. |
2. In addition to this, we have the option to print the lines using colours different than the one that is selected as the default and that is plotted in the output curve. But, in order to do this operation, we will need to adhere to the same set of instructions as before. In order for the line of curve that is displayed in the output to be printed in the colour of our choosing, we will need to utilise the colour parameter as an extra argument when we are working within the plot() method. This may be comprehended by the implementation of the extra parameter in the following sample programme: Example 3:
Have a look at the following Python programme, which will use the PyLab to draw a curve in the output while utilising a variety of different colours.
Module:
W01A1@@@4 Output:
Explanation: 
Related:
The reasoning that we utilised in the programme that was shown in the example before this one has been included into this one as well. In order to display the curve with a line of many colours in the output, we made advantage of the colour parameter that was provided in the plot() method of this programme. At the end, we displayed the curve using the show() method, making sure to include our specialised variable in the result.
The result shows that the curve is presented with the X and Y-axis points, which we have specified within the ‘a’ and ‘b’ variables, respectively. In addition, the curve has a yellow colour line since we provided an extra colour parameter when using the plot() method.
If we want to display a straight line with the colour of our choosing in it, we may use the following set of colour codes as the extra parameter within the plot() method.
curve:
| Colour codes | w, k, y, m, c, r, g, b |
4. If you are curious as to whether or not we are able to carry out both of these operations (producing a symbol line rather than a straight line and printing it with the colour of choosing) concurrently, the answer is “yes.” We are able to carry out both of the responsibilities at the same time; all that is required of us is to give both of the parameters inside the plot() method as a single extra argument in the form of ‘_y.’ Then, it will carry out both of the actions at the same time, and the outcome will consist of a curve that has a symbol line written in the colour of our choosing. This may be comprehended by the implementation of the extra parameter in the following sample programme: Example 4:
Have a look at the following Python programme, in which a curve will be plotted in the output using the PyLab.
Module:
W01A1@@@5 Output:
The result shows that we have printed a curve with a symbol line that is filled with various colours, as is seen in the output.
4. As a conclusion, we should mention that it is possible for us to print numerous curves inside a single plot and superimpose them on top of one another; in order to do this, we just need to combine many instances of the plot() function within a single programme. By using the many plot() function in the following example programme, we are able to have a better understanding of this strategy through: Example 5:
Have a look at the following Python programme, in which we have used the plot() method more than once to overlay the data.
curve:
W01A1@@@6 Output:
By making many calls to the plot() method throughout the programme, as is seen in the output, we were able to display multiple curves and superimpose them on top of one another.