matplotlib.pyplot.axhline

matplotlib.pyplot.axhline(y=0, xmin=0, xmax=1, hold=None, **kwargs) [source]

Add a horizontal line across the axis.

Parameters:

y : scalar, optional, default: 0: y position in data coordinates of the horizontal line.
xmin : scalar, optional, default: 0: Should be between 0 and 1, 0 being the far left of the plot, 1 the far right of the plot.
xmax : scalar, optional, default: 1: Should be between 0 and 1, 0 being the far left of the plot, 1 the far right of the plot.

Returns:

line : Line2D

Other Parameters:

**kwargs :

Valid kwargs are Line2D properties, with the exception of 'transform':

Property	Description
`agg_filter`	a filter function, which takes a (m, n, 3) float array and a dpi value, and returns a (m, n, 3) array
`alpha`	float (0.0 transparent through 1.0 opaque)
`animated`	bool
`antialiased` or aa	bool
`clip_box`	a `Bbox` instance
`clip_on`	bool
`clip_path`	[(`Path`, `Transform`) \| `Patch` \| None]
`color` or c	any matplotlib color
`contains`	a callable function
`dash_capstyle`	['butt' \| 'round' \| 'projecting']
`dash_joinstyle`	['miter' \| 'round' \| 'bevel']
`dashes`	sequence of on/off ink in points
`drawstyle`	['default' \| 'steps' \| 'steps-pre' \| 'steps-mid' \| 'steps-post']
`figure`	a `Figure` instance
`fillstyle`	['full' \| 'left' \| 'right' \| 'bottom' \| 'top' \| 'none']
`gid`	an id string
`label`	object
`linestyle` or ls	['solid' \| 'dashed', 'dashdot', 'dotted' \| (offset, on-off-dash-seq) \| `'-'` \| `'--'` \| `'-.'` \| `':'` \| `'None'` \| `' '` \| `''`]
`linewidth` or lw	float value in points
`marker`	`A valid marker style`
`markeredgecolor` or mec	any matplotlib color
`markeredgewidth` or mew	float value in points
`markerfacecolor` or mfc	any matplotlib color
`markerfacecoloralt` or mfcalt	any matplotlib color
`markersize` or ms	float
`markevery`	[None \| int \| length-2 tuple of int \| slice \| list/array of int \| float \| length-2 tuple of float]
`path_effects`	`AbstractPathEffect`
`picker`	float distance in points or callable pick function `fn(artist, event)`
`pickradius`	float distance in points
`rasterized`	bool or None
`sketch_params`	(scale: float, length: float, randomness: float)
`snap`	bool or None
`solid_capstyle`	['butt' \| 'round' \| 'projecting']
`solid_joinstyle`	['miter' \| 'round' \| 'bevel']
`transform`	a `matplotlib.transforms.Transform` instance
`url`	a url string
`visible`	bool
`xdata`	1D array
`ydata`	1D array
`zorder`	float

Examples

draw a thick red hline at 'y' = 0 that spans the xrange:
```
>>> axhline(linewidth=4, color='r')
```
draw a default hline at 'y' = 1 that spans the xrange:
```
>>> axhline(y=1)
```
draw a default hline at 'y' = .5 that spans the middle half of the xrange:
```
>>> axhline(y=.5, xmin=0.25, xmax=0.75)
```