How to remove outline of circle marker when using pyplot.plot in matplotlib

Question

I’m producing a scatter plot using pyplot.plot (instead of scatter – I’m having difficulties with the colormap)

I am plotting using the ‘o’ marker to get a circle, but the circle always has a black outline.

How do I remove the outline, or adjust its colour?

Asked By: Toam

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Answer 1

To remove the outline of a marker, and adjust its color, use markeredgewidth (aka mew), and markeredgecolor (aka mec) respectively.

Using this as a guide:

import numpy as np
import matplotlib.pyplot as plt

x = np.arange(0, 5, 0.1)
y = np.sin(x)

plt.plot(x,
         y,
         color='blue',
         marker='o',
         fillstyle='full',
         markeredgecolor='red',
         markeredgewidth=0.0)

This produces:

As you notice, even though the marker edge color is set, because the width of it is set to zero it doesn’t show up.

Answered By: jrd1

Answer 2

From the pyplot API docs:

markeredgecolor or mec any matplotlib color

Example:

In [1]: import matplotlib.pyplot as plt

In [2]: import numpy as np

In [3]: x = np.linspace(0,1,11)

In [4]: y = x * x

In [5]: plt.plot(x,y,'o',color="red", ms=15, mec="red")
Out[5]: [<matplotlib.lines.Line2D at 0x34e1cd0>]

In [6]: plt.show()

Yields:

Is that what you’re looking for?

Answered By: Andrey Sobolev

Answer 3

This is outlined in matplotlib.axes.Axes.scatter documentation found at https://matplotlib.org/api/_as_gen/matplotlib.axes.Axes.scatter.html

It specifies that line edge colors for scatter plot markers can be set with

 edgecolors : color or sequence of color, optional, default: ‘face’
 The edge color of the marker. Possible values:

 - ‘face’: The edge color will always be the same as the face color.
 - ‘none’: No patch boundary will be drawn.
 - A matplotib color.

 For non-filled markers, the edgecolors kwarg is ignored and forced to ‘face’ internally.

The width of the line edges can be specified with

`linewidths` : scalar or array_like, optional, default: None

The linewidth of the marker edges.

Note: The default edgecolors is ‘face’.

You may want to change this as well. If None, defaults to rcParams lines.linewidth.

Answered By: nicholasericksen

How to remove outline of circle marker when using pyplot.plot in matplotlib

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