In this tutorial, we’ll try to understand how to change the thickness of a line in a matplotlib plot with the help of some examples.

## Using the `linewidth`

parameter

We can easily adjust the thickness of the line in matplotlib plots using the `linewidth`

argument to the `matplotlib.pyplot.plot()`

function.

**Basic syntax:**

matplotlib.pyplot.plot(x, y, linewidth=1.5)

When we generate a plot in matplotlib, it has a default linewidth of 1.

So, If we want to increase the line thickness we need to adjust the `linewidth`

parameter value to be greater than 1, and to decrease the line thickness we need to adjust the `linewidth`

parameter value to be less than 1.

## Examples

Now let us see some examples to demonstrate the above argument function.

### Example 1 – Changing the linewidth of a straight line

Let’s plot a line plot and see its width by default.

import matplotlib.pyplot as plt import numpy as np x = np.linspace(0, 10, 100) y1 = 1*x + 4 plt.plot(x, y1) plt.show()

Output:

We first import the required modules in the above code (numpy and matplotlib). Then, we create a set of x values using the `numpy.linspace`

method(more about the method here). And finally, we create the y values of the line `y = (1*x) + 4`

which forms a straight line.

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Let’s now replot the above chart but make the line thicker in the plot by using the `linewidth`

parameter.

# make the line thicker plt.plot(x, y1, linewidth=5) plt.show()

Output:

The line is now much thicker.

### Example 2 – Changing the linewidth of a curve

We can similarly change the thickness of a curve in matplotlib using the `linewidth`

parameter.

import matplotlib.pyplot as plt import numpy as np x = np.linspace(0, 10, 100) y = np.sin(x)*np.exp(-x/3) plt.plot(x, y, linewidth=10) plt.show()

Output:

We first import the required modules in the above code (numpy and matplotlib). Then we create a set of x values using `numpy.linspace`

method(more about the method here). Then, we create the y values of the curve `y = sinx*e^(-x/3)`

which forms a curve. Note that we are specifying a custom linewidth for the curve here.

You can see that the resulting curve is thick.

### Example 3 – Changing the linewidth of multiple curves

You can modify the linewidth of more than one line or curve. For this, specify the `linewidth`

when plotting the respective line/curve.

import matplotlib.pyplot as plt import numpy as np x = np.linspace(0, 10, 100) y1 = np.sin(x)*np.exp(-x/3) y2 = np.sin(x)*np.exp(-x/7) plt.plot(x, y1, linewidth=10) plt.plot(x, y2, linewidth=0.5) plt.show()

Output:

We first import the required modules in the above code (numpy and matplotlib). Then we create a set of x values using `numpy.linspace`

method. Then, we create the y1 values of the curve y = sinx*e^(-x/3) which forms a curve, and y2 values of the curve `y = sinx*e^(-x/7)`

which also forms a curve. Note that we specify different line widths for both curves.

You can see that the curves have the specified line widths.

You might also be interested in –

- How to remove the legend border (frame) in Matplotlib?
- How to change the legend position in Matplotlib?
- Matplotlib – Change Line to Dots
- Matplotlib – Add an Average Line to the Plot

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