Suppose, I have the following two lists that correspond to x- and y-coordinates.
x = [1,2,3,4,5,6]
y = [3,4,5,6,7,8]
I want the first pair (1,3) to be in a different color or shape.
How can this be done using python?
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Do you want to change the color and shape of the first pair in a scatterplot?KenHBS– KenHBS2017-01-05 16:18:12 +00:00Commented Jan 5, 2017 at 16:18
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2 Answers
One of the simplest possible answers.
import matplotlib.pyplot as plt
x = [1,2,3,4,5,6]
y = [3,4,5,6,7,8]
plt.plot(x[1:], y[1:], 'ro')
plt.plot(x[0], y[0], 'g*')
plt.show()
1 Comment
Bill Bell
It means green asterisk -- like this * but green.
More flexibility is offered with scatter() call where you can change marker style, size and color more intuitively (e.g. D for diamond).
x = [1,2,3,4,5,6]
y = [3,4,5,6,7,8]
plt.scatter(x[1:], y[1:], c='blue')
plt.scatter(x[0], y[0], c='red', marker='D', s=100);
# you can even write text as a marker
plt.scatter(x[0], y[0], c='red', marker=r'$\tau$', s=100);
If the point to highlight is not the first point, then a filtering mask might be useful. For example, the following code highlights the third point.
plt.scatter(*zip(*(xy for i, xy in enumerate(zip(x, y)) if i!=2)), marker=6)
plt.scatter(x[2], y[2], c='red', marker=7, s=200);
Perhaps, the filtering is simpler with numpy.
data = np.array([x, y]) # construct a single 2d array
plt.scatter(*data[:, np.arange(len(x))!=2], marker=6) # plot all except the third point
plt.scatter(*data[:, 2], c='red', marker=7, s=200); # plot the third point
As a side note, you can find the full dictionary of marker styles here or by matplotlib.markers.MarkerStyle.markers.
# a dictionary of marker styles
from matplotlib.markers import MarkerStyle
MarkerStyle.markers