**Matplotlib**

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**Graphs Cookbook**

# Drawing a horizontal line in Matplotlib

*schedule*May 20, 2023

*toc*Table of Contents

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To draw a horizontal line in Matplotlib, use the `axhline(~)`

function like so:

```
plt.axhline(y=0.5)
```

The output is as follows:

# Changing the color

To change color of the line, add the `color`

parameter:

```
color="red" color="#FF0000"
```

# Changing the line style

To change the styling of the line, add the `linestyle`

parameter:

```
linestyle="dotted"linestyle="dashed"
```

# Specifying the starting and endpoint points

By default, the line drawn by `axhline(~)`

spans the entire width of the graph.

## xmin and xmax

You could change this behavior by specifying parameters `xmin`

and `xmax`

, both of which must be a number between 0 and 1.Here, 0 represents the left-side of your graph, while 1 represents the right-side of your graph.

To draw a horizontal line from left 25% to right 75%:

```
plt.xlim(0, 10)plt.axhline(y=2, xmin=0.25, xmax=0.75)
```

The output is as follows:

## x-coordinates

Unfortunately, the `axhline(~)`

method does not accept starting and ending x-coordinates. We can instead resort to the `plt.plot(~)`

function, which does allow for x-coordinates.

To draw a horizontal line from `x=2`

to `x=8`

at `y=5`

:

```
plt.xlim(0, 10)plt.plot([2,8], [5,5])
```

The output is as follows: