How to create a polar plot using matplotlib python

Polar projections transfer data from a Cartesian to a polar coordinate system. A polar plot is a graph drawn using a polar coordinate system. Polar axes represent the polar coordinate system, and we show the polar curves. 

We can use the polar plot to display circular or radial symmetry data. It displays symmetry-like data from a sensor. It monitors signals in all directions around a central point. It is a natural way to measure angles and distances from a central point. We can use the polar coordinate system to record such data. 

Python Packages required to create a polar plot: 

• Matplotlib allows you to create polar graphs with the pyplot module. A function such as a plot() can plot polar curves utilizing the theta range and distance from the origin. It creates a polar plot. 
• The numpy library can generate numpy arrays of data for use in the plot function. 

A polar plot's first plot is often a circle with a radius of one, representing the unit circle. The plot() function can add other plots to the polar plot. We can use the sinusoid to make a rose-shaped sinusoid and an identical circle. It helps make a fixed-radius circle. The angle and distance from the origin represent data in a polar plot. A given angle represents the data's direction from the origin. A specified distance represents its magnitude. 

How to create a polar plot using matplotlib in Python  

We can use the polar() function in Matplotlib to create a polar plot. This program generates a new polar coordinate system. It converts the plotting area to polar coordinates. Finally, we can plot the data on this polar coordinate system. It will use normal Matplotlib plotting functions like plot() and scatter(). 

The code uses the plt.polar() function to create two polar curves, one in red and one in blue. The 'red_thetas' and 'red_rs' arrays for the red curve. The 'blue_thetas' and 'blue_rs' arrays for the blue curve use the code. The 'c' parameter sets the color of each curve. The 'label' parameter sets the label for the corresponding legend entry. 

Preview of the output obtained when polar() function is used

Code

The code uses the plt.polar() function to create two polar curves, one in red and one in blue, using the 'red_thetas' and 'red_rs' arrays for the red curve, and the 'blue_thetas' and 'blue_rs' arrays for the blue curve. The 'c' parameter sets the color of each curve and the 'label' parameter sets the label for the corresponding legend entry.

Follow the steps carefully to get the output easily.

• Install Visual Studio Code in your computer.
• Install the required library by using the following command -

pip install matplotlib

pip install numpy

• If your system is not reflecting the installation, try running the above command by opening windows powershell as administrator.
• Open the folder in the code editor, copy and paste the above kandi code snippet in the python file.
• Run the code using the run command.

I hope you found this useful. I have added the link to dependent libraries, version information in the following sections.

I found this code snippet by searching for "how to create a polar plot using matplotlib python" in kandi. You can try any such use case!

Dependent libraries

FAQ

What is the polar coordinate system? How does it differ from the Cartesian coordinate system?  

The distinction between both coordinate systems is how we represent the points. An angle and a distance represent points in the polar coordinate system. The perpendicular axes represent points in the Cartesian coordinate system. The polar coordinate system represents circular or angular data. But the Cartesian coordinate system represents linear data. 

How can I use Python Matplotlib to create a polar plot?  

The plt.polar() method lets you construct a polar plot without first creating an axis object. You can use the subplot() with the projection='polar' option and plot data with the plot() function. The plt.polar() function is a quick and easy way to make a simple polar plot. It provides customization choices than building an axis object using the plot() function. 

How do I set the theta range in a polar plot using Python Matplotlib?  

To set the range of theta in a polar plot, you can use the set_thetamin() and set_thetamax() methods of the axis object. 

How can I use the numpy library to assist with plotting a sinusoid for my polar plot in Python code?  

We can use the numpy library's linspace() function to generate an array of angles theta. In this case, the linspace() function generates a linearly spaced array of values. Between the start and finish positions, 0 and 2π radians. The sine of 5 times the angles theta will help generate an array of radial distances r. It uses the sin() function of the numpy library. This produces a sinusoidal curve that oscillates five times around the circle. 

How do I adjust a given angle to fit into my Python code for creating a polar plot?  

To make a given angle fit into your Python code for making a polar plot, you must convert it to radians. Use the numpy library's deg2rad() method to convert degrees to radians. 

If you do not have matplotlib and numpy that is required to run this code, you can install it by clicking on the above link and copying the pip Install command from the pages in kandi.

You can search for any dependent library on kandi like matplotlib.

Environment tested

1. This code had been tested using python version 3.8.0
2. matplotlib version 3.7.1 has been used.
3. numpy version 1.24.2 has been used.

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