Plot a Vertical Line Using Matplotlib in Python

Introduction:

In this tutorial, we are learning about how to plot a vertical line using Matplotlib in Python. Python provides a powerful library called Matplotlib that can create graphical representations. One of the many features of this library is the ability to draw vertical lines, which is useful for adding instructions or showing specific details of the plot. Matplotlib's built-in methods "axvline()", "vlines()" and "plot()" are used to plot vertical lines with adjustable parameters such as position, color and line style. We will explain this process with the help of sample programs. Let us discuss Matplotlib's design process and its example that will show us how to draw a vertical line.

Method 1: Using the axvline() Method

This is the easiest way to draw vertical lines in Matplotlib. Its advantages are simplicity and convenience. However, its disadvantage is that it does not allow us to specify the y range of the line. The axvline() method takes an argument to specify the x coordinate of the vertical line. It may require additional arguments, which we will discuss later.

Syntax:

The syntax of the axvline() method is given in below -

Parameters:

The parameters of the axvline() method are given in below -

x: The position of the X axis to draw a line. It accepts the numbers.
color: It is used to color the line. For example, "n" or "c".
xmin and xmax: It is scalar, optional, and default: 0/1. Draws a line in a specific range.
linestyle: It specifies the type of line that accepts a string. For example, '-', '-', '-.', ':', 'none', ',', 'dashed line', 'dotted line', 'dashdot', 'solid'.

Program Code 1:

Here, we give a program code to plot a vertical line using the axvline() method to Matplotlib in Python. The code is given below -

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np
 
# The plot size is specified here
plt.figure(figsize = (11, 7))
 
# Here, we only specified one line with the level of full height
plt.axvline(x = 9, color = 'c', label = 'axvline - full height')
 
# The final graph is show here
plt.show()

Output:

After compiling and running the above code then we will find the following graph. The image is given in below -

Plot a Vertical Line Using Matplotlib in Python

Program Code 2:

Here, we give another program code to plot a vertical line using the axvline() method to Matplotlib in Python. However, this time, we will adjust the appearance of the line by passing additional parameters to axvline(), such as color, line style, and alpha. The code is given below -

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np

# Here, we only specified one line with the line style
plt.axvline(x = 5, color = 'blue', linestyle = ':', alpha = 0.8)

# The final graph is show here
plt.show()

Output:

After compiling and running the above code then we will find the following graph. The image is given in below -

Method 2: Using the plot() Method

Here is another way to plot vertical lines in Matplotlib. Unlike axvline(), it allows us to specify the y part of the line. To plot a vertical line using the plot() function, pass two points with the same x coordinate and different y coordinate as arguments. The plot() method in the pyplot module of the Matplotlib library is used to draw a hexagonal plot of x and y points.

Syntax:

The syntax of the plot() method is given in below -

Parameters:

The parameters of the plot() method are given in below -

x_points and y_points: The x and y points are used to plot in the graph.
scaley = False: Bool, these constraints determine whether the constraint will allow access to data limits.

Program Code 1:

Here, we give a program code to plot a vertical line using the plot() method to Matplotlib in Python. The code is given below -

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np
 
# The plot size is specified here
plt.figure(figsize = (11, 7))
 
# Here, we only specified the plot coordinates
plt.plot((1, 1), (1, 0), scaley = False)
 
# The final graph is show here
plt.show()

Output:

After compiling and running the above code then we will find the following graph. The image is given in below -

Program Code 2:

Here, we give another program code to plot a vertical line using the plot() method to Matplotlib in Python. Here we will adjust the appearance of the line by passing additional parameters to plot(), such as color, linestyle, and marker. The code is given below -

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np

# Here, we only specified the plot coordinates
plt.plot([3, 3], [1, 3], color = 'red', linestyle = '--', marker = 'o')

# The final graph is show here
plt.show()

Output:

After compiling and running the above code then we will find the following graph. The image is given in below -

Method 3: Using the vlines() Method

In the matplotlib.pyplot.vlines(), vlines are short for vertical lines. How this works is very clear from the description of the function, which says that it keeps the shape of the vertical line along the axes. Here are three ways to plot vertical lines in Matplotlib. It must have three parameters: x, ymin, and ymax, which are the x coordinate of the vertical line, the lower y coordinate, and the upper y coordinate, respectively.

Syntax:

The syntax of the vlines() method is given in below -

Parameters:

The parameters of the vlines() method are given below -

x: The position of the X axis to draw a line. It accepts the numbers.
color: It is used to color the line. For example, "n" or "c".
ymin and ymax: It is scalar, optional, and default: 0/1. Draws a line in a specific range.
linestyle: It specifies the type of line that accepts a string. For example, '-', '-', '-.', ':', 'none', ',', 'dashed line', 'dotted line', 'dashdot', 'solid'.

Program Code 1:

Here we give a program code to plot a vertical line using the vlines() method to Matplotlib in Python. The code is given below -

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np
 
# An array is defined here
x = [2, 90]
 
# The plot size is defined here
plt.figure(figsize = (15, 9))
 
# Here, we only specified the plot coordinates 
plt.vlines(x = 54, ymin = 0, ymax = max(x), colors = 'c', label = 'vline_multiple - full height')

# The final graph is show here
plt.show()

Output:

After compiling and running the above code then we will find the following graph. The image is given in below -

Program Code 2:

Here we give another program code to plot a vertical line using the vlines() method to Matplotlib in Python. In this example, we will change the appearance of the lines by passing additional parameters to vlines(), such as color and line width. The code is given below -

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np

# Here, we only specified the plot coordinates
plt.vlines(x = 1, ymin = 2, ymax = 5, color = 'red', linewidth = 5)

# The final graph is show here
plt.show()

Output:

By changing the code in the previous example, we drew the red line with a thick line width of 5. After compiling and running the above code then we will find the following graph. The image is given in below -

Program Code 3:

# Here, we import the required packages 
import matplotlib.pyplot as plt
import numpy as np
 
# An array is defined here
x = [2, 90]
 
# The plot size is defined here
plt.figure(figsize = (15, 9))
 
# Here, we only specified the plot coordinates for draw multiple lines
plt.vlines(x = [30, 31.15, 35.55], ymin = 0, ymax = max(x), colors = 'r', label = 'vline_multiple - full height')
 
# Here, we plot multiple lines with the varying ymin and ymax
plt.vlines(x = [37, 37.25, 38], ymin = [0, 25, 50], ymax = max(x), colors = 'b', label = 'vline_multiple - partial height')
 
# Here, we plot single line with the full ymin and ymax
plt.vlines(x = 38, ymin = 0, ymax = max(x), colors = 'c', label = 'vline_single - full height')
 
# Here, we plot single line with the specific ymin and ymax
plt.vlines(x = 40.5, ymin = 35, ymax = max(x), colors = 'g', label = 'vline_single - partial height')
 
# The final graph is show here
plt.show()

Output:

After compiling and running the above code then we will find the following graph. The image is given in below -

Conclusion:

In this tutorial, we are learning about how to plot a vertical line using Matplotlib in Python. Python provides a powerful library called Matplotlib that can create graphical representations. Matplotlib is a library in Python that creates 2D plots to visualize data. Visualization always helps analyze data better and improve users' decision-making process. In this matplotlib tutorial, we will plot some vertical lines, and we will change some things like font, label, linewidth, etc. We found three ways to plot vertical lines in Python using the "axvline()", "vlines()" and "plot()" methods. Each method has some advantages as well as some disadvantages depending on our needs and preferences. Here, we share some program codes of these methods along with their outputs.

Next TopicPretty printing xml in python

← prev next →