# Draw vertical line matplotlib

In this Python tutorial, we will discuss Draw vertical line matplotlib in python. Here we will cover different examples related to vertical lines using matplotlib. And we will also cover the following topics:

• Draw vertical line matplotlib
• Draw vertical dotted line matplotlib
• Matplotlib draw vertical line with label
• Matplotlib draw multiple vertical line
• Plot vertical line matplotlib datetime
• Matplotlib draw vertical line between two points
• Plot vertical line segment matplotlib
• Plot vertical line on histogram matplotlib

## Draw vertical line matplotlib

In this section, we learn about how to plot or draw a vertical line in matplotlib in Python. Before starting the topic, firstly we have to understand what is a vertical line or how it looks.

In general, a vertical line is a straight line that goes from top to bottom and vice versa. Or If we talk in coordinates plane, a line parallel to Y-axis is known as a vertical line.

In Python, matplotlib is a popular library used for plotting. It provides different methods to draw a vertical line which we discussed below.

• Using plot()
• Using vlines()
• Using axvline()

### By using plot() method

In matplotlib, the plot() method is used to draw a 2D plot.

The syntax of the plot() method is as given below:

``matplotlib.pyplot.plot(x_points, y_points)``

The parameters used above are outlined as below:

• x_points: specify x coordinates points to plot.
• y_points: specify y coordinates points to plot.

Let’s have a look at an example to clearly understand the concept:

``````# Import Library

import matplotlib.pyplot as plt

# Define Data

X = [0, 0]
Y = [5, 10]

# Plot vertical line

plt.plot(X,Y)

# Show

plt.show()``````
• In the above example, we import matplotlib.pyplot library.
• After this, we define data points for plotting. Here we specify the x-axis to 0 because we want to draw a vertical line.
• Next, we use plt.plot() method for plotting a line and plt.show() method to visualize plot on the user’s screen.

### By using vlines()

In matplotlib, the vlines() method is used to draw vertical lines across the axes. Here vlines stand for vertical lines.

The syntax of the vlines() method is as given below:

``matplotlib.pyplot.vlines(x, ymin, ymax, colors, linestyles)``

The parameters used above are described as below:

• x: specifies the position on the x-axis to plot the line.
• ymin and ymax: specify the beginning and end of each line. These attributes are compusolary.
• colors: specify the color of the line.
• linestyle: specify the style or type of the line.

Let’s see an example of the vertical line created by using the vlines() method:

``````# Import Library

import matplotlib.pyplot as plt

# Plot vertical line

plt.vlines(9, 2, 3, color='red')

# Show

plt.show()``````
• In the above example, we import matplotlib.pyplot library.
• By using plt.vlines() method we plot vertical line. Here we pass x, ymin, ymax, color as an argument and set its value to 9, 2, 3, red respectively.

### By using axvline()

In matplotlib, the axvline() method is used to add vertical lines to the plot.

The syntax of the axvline() method is as given below:

``matplotlib.pyplot.axvline(x, ymin, ymax, color, linestyle)``

The above-used parameters are described as below:

• x: specify position on the x-axis to plot the line.
• ymin and ymax: specify the starting and ending range of the line.
• color: specify the color of the line.
• linestyle: specify the style or type of the line.

Example of axvline() method:

``````# Import Library

import matplotlib.pyplot as plt

# Plot vertical line

plt.axvline(x=3, ymin=0.25, ymax=0.75)

# Show

plt.show()``````

Here we use the axvline() method to draw a vertical line and pass the x, ymin, ymax as a parameter and set its value to 3, 0.25, 0.75 respectively.

## Draw vertical dotted line matplotlib

Here we are going to learn how we can draw vertical dotted lines in matplotlib in python. We have to change the line style of lines to make them dotted in style.

Matplotlib.pyplot library provides the parameter linestyle to set types of lines.

Let’s see an example of a vertical dotted line:

``````# Import Library

import matplotlib.pyplot as plt

# Plot vertical dotted line

plt.axvline(x=5, ymin=0.25, color='red', linestyle='dotted', linewidth=5)

# Show

plt.show()``````
• Here we use the axvline() method to draw a dotted vertical line. We pass parameters x, ymin, color, linestyle, and linewidth.
• Our main aim is to draw a vertical line that is dotted in nature, so we set linestyle to dotted and increase width of the line by using linewidth parameter.

Also, read: Matplotlib plot a line

## Matplotlib draw vertical line with label

In this section, we are going to learn how to draw vertical lines with labels. Here we use the axvline() method to draw a vertical line and pass label as a parameter.

The syntax to draw a vertical line with label:

``matplotlib.pyplot.axvline(x, ymin, ymax, color, label)``

Example:

``````# Import Library

import matplotlib.pyplot as plt

# Plot vertical line

plt.axvline(x=10, linewidth=5, label= 'vertical-line')

plt.legend(loc = 'upper left')

# Show

plt.show()``````
• By using the plt.axvline() method we draw a vertical line and pass the parameter label.
• Then by using the plt.legend() method we set the location of the label to the upper left.

## Matplotlib draw multiple vertical line

Here we are going to create multiple vertical lines in matplotlib in python. The methods used to create multiple vertical lines are:

• Using axvline()
• Using vlines()

### By using axvline()

In matplotlib, by using the axvline() method we can create multiple vertical lines in the plot.

Let’s see an example related to this:

``````# Import library

import matplotlib.pyplot as plt

# Vertical line 1

plt.axvline(x = 5, color = 'b')

# Vertical line 2
# We also set range of the line

plt.axvline(x = 3, ymin = 0.2, ymax = 2, color='red')

# Display

plt.show()``````

### By using vlines()

In matplotlib, by using the vlines() method we can create multiple vertical lines in the plot.

Example:

``````# Import library

import matplotlib.pyplot as plt

# Vertical line 1

plt.vlines(x = 5, ymin = 1, ymax = 2, color = 'black')

# Vertical line 2

plt.vlines (x = 3, ymin = 1.98, ymax = 1.5, color='red')

# Vertical line 3

plt.vlines (x = [1, 2, 3] , ymin = 0.2, ymax = 0.6, color = 'orange')

# Vertical line 4

plt.vlines (x = 10, ymin = 0.2, ymax = 2, color='yellow')

# Display

plt.show()``````

## Plot vertical line matplotlib datetime

Here we draw a vertical line on datetime plot in matplotlib in python.

For this firstly, you have to import the datetime library and after this, by using the axvline() or vlines() method you can draw a vertical line.

Let’s see an example:

``````# Import Library

import matplotlib.pyplot as plt
import datetime

# Vertical line

plt.axvline(datetime.datetime.now())

# Print date and time

print(datetime.datetime.now())

# Format date

plt.gcf().autofmt_xdate()

# Show

plt.show()``````

In the above example we use:

• datetime.datetime.now() : specify today dates and time
• autofmt_xdate() : auto formate the dates at x-axis.

## Matplotlib draw vertical line between two points

Here we are going to learn how we draw a vertical line between two points or data markers.

Let’s see an example where we connect two points using the vertical line:

``````# Import Library

import matplotlib.pyplot as plt

# Define data

x = [2, 3, 4, 5]
y = [(2, 5), (1, 3), (6, 4), (2, 7)]

# Plot

plt.plot(x, [i for (i,j) in y], 'co', markersize = 7)
plt.plot(x, [j for (i,j) in y], 'mo', markersize = 7)

# Vertical line

plt.plot((x,x),([i for (i,j) in y], [j for (i,j) in y]),c='red')

# Display

plt.show()``````
• Firstly, we import matplotlib.pyplot library. After this, we define data on the x-axis and y-axis.
• Then we use plt.plot() method to plot markers or points here we pass x data point and use for loop for defining y data point.
• Now for connecting two points we pass x, y, color as a parameter. Here we set (x,x) for the x-axis point and use for loop for connecting the y-axis point.

## Plot vertical line segment matplotlib

Here we are going to see an example where we draw a vertical line segment in the plot in matplotlib.

Example:

``````# Import Library

import matplotlib.pyplot as plt
import numpy as np

# Define Data

x = np.arange(0, 15, 0.2)
y = np.sin(x)

# Plot figure

plt.plot(x, y)

# Vertical line

plt.axvline(x=7.9,color='red')

# Title

plt.title("Sine Function", fontsize= 15, fontweight='bold')

# Generate Plot

plt.show()``````
• In the above example, we firstly import matplotlib.pyplot, and numpy library.
• After this, we define data using arange() and sin() method.
• By using the plt.plot() method we plot a graph.
• Then use the axvline() method to draw a vertical line.Here we pass x and color as a parameter.
• plt.title() is used to add a title to the plot and plt.show() method is used to display the plot on the user’s screen.

## Plot vertical line on histogram matplotlib

Sometimes programmers want to find the mean of the histogram bars or the function. In that case, we need a vertical line in the histogram to represent mean of the each bar or a function.

Firstly, you have to know how to create a histogram. Let’s see the syntax to create a histogram.

``matplotlib.pyplot.hist(x, bins, color, edgecolor, ....)``

Let’s see an example where we draw a vertical line on the histogram:

``````# Import Library

import numpy as np
import matplotlib.pyplot as plt

# Define data

np.random.random()
x = np.random.gamma(15, 1.5, 50)

# Plot histogram

plt.hist(x, bins=10, color='m', edgecolor='k')

# Vertical line

plt.axvline(x.mean(), color='k', linestyle='dotted', linewidth=5)

# Display

plt.show()``````
• In the above example, we import matplotlib.pyplot, and numpy packages.
• Next, we define data using random.gamma() method here we pass the shape, scale, and size as a parameter.
• Then we use plt.hist() method to draw a histogram for the sample data created.
• By using plt.axvline() method we draw a vertical line at the mean of the defined sample data.