Matplotlib Scatter Plot – scatter() Function

The Scatter plot is a type of plot that is used to show the data as a collection of points.

  • This plot is mainly used to observe the relationship between the two variables.
  • Scatter plots make use of dots to represent the relationship between two variables.
  • These plots are mainly used to plot data points on the horizontal and vertical axis in order to show how much one variable is affected by another.
  • In 2-Dimensions it is used to compare two variables while in 3-Dimensions it is used to make comparisons in three variables.

Matplotlib scatter() Function

The method scatter() in the pyplot module in matplotlib library of Python is mainly used to draw a scatter plot.

The syntax to use this method is given below:

matplotlib.pyplot.scatter(x_axis_data, y_axis_data, s, c, marker, cmap, vmin, vmax,alpha,linewidths, edgecolors)

Function Parameters:

Let us discuss the parameters of scatter() method:

  • x_axis_dataThis parameter indicates an array containing x-axis data.
  • y_axis_dataThis parameter indicates an array containing y-axis data.
  • s<This parameter indicates the marker size (it can be scalar or array of size equal to the size of x or y). It is an optional parameter and the default value is None.
  • cThis parameter indicates the color of sequence and it is an optional parameter with default value equals to None.
  • markerThis parameter is used to indicate the marker style. The default value of this parameter is None and it is also an optional parameter.
  • cmapThis optional parameter indicates cmap name with default value equals to None.
  • linewidthsThis parameter indicates the width of the marker border and having None as default value.
  • edgecolorsThis parameter is used to indicate the marker border-color and also it’s default value is None.
  • alphaThis option indicates the blending value, between 0 (transparent) and 1 (opaque).

Let us dive into some examples and create some scatter plots.

Simple Scatter Plot Example:

Below we have a code snippet to create a simple scatter plot. Let us go through the code snippet:

import matplotlib.pyplot as plt 

x =[5, 7, 8, 7, 2, 17, 2, 9, 4, 11, 12, 9, 6] 
y =[99, 86, 87, 88, 100, 86, 103, 87, 94, 78, 77, 85, 86] 
plt.scatter(x, y, c ="red") 

When you run the above code on your machine you will see the output as shown below:

scatter plot example matplotlib

Scatter Plot with large Dataset:

Let us create another scatter plot with different random numbers and the code snippet is given below:

import numpy as np
import matplotlib.pyplot as plt

# Creating the data
N = 1000
x = np.random.rand(N)
y = np.random.rand(N)
colors = (0,0,0)
area = np.pi*3

plt.scatter(x, y, s=area, c=colors, alpha=0.5)
plt.title('Scatter plot')

The output for the same is as follows:

scatter plot example matplotlib

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