"如何获得 matplotlib.pyplot.scatter 的默认蓝色？"

Question

How do I get the shade of blue that is used as default in matplotlib.pyplot.scatter ? When giving the keyword argument c='b' , it gives a darker shade of blue. In this documentation of matplotlib.pyplot.scatter , it says the default is supposed to be 'b' , yet it looks different.

See example below:

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.scatter(-1, 0)
ax.text(-1, 0, 'Default blue')
ax.scatter(1, 0, c='b')
ax.text(1, 0, 'Darker blue')
ax.set_xlim(-2, 2)

I'm using Python 3.5 with Matplotlib 2.0.0. The reason why I'm asking this, is because I would like to use the same blue colour when plotting some of the points one by one with plt.plot() .

Answer 1

The default colour cycle was changed in matplotlib version 2 as shown in the docs .

Therefore, to plot the "new" default blue you can do 2 things:

fig, ax = plt.subplots()

ax.scatter(-1, 1)
ax.text(-0.9, 1, 'Default blue')

ax.scatter(1, 1, c='#1f77b4')
ax.text(1.1, 1, 'Using hex value')

ax.scatter(0, 0.5, c='C0')
ax.text(0.1, 0.5, 'Using "C0" notation')

ax.set_xlim(-2, 3)
ax.set_ylim(-1,2)
plt.show()

Which gives:

Alternatively you can change the colour cycle back to what it was:

import matplotlib as mpl
from cycler import cycler

mpl.rcParams['axes.prop_cycle'] = cycler(color='bgrcmyk')

Answer 2

As noted in the docs<\/a> , the default color cycle is the "Tableau Colors". These can be accessed using 'tab:blue'<\/code> , 'tab:orange'<\/code> , 'tab:green'<\/code> , etc.

import matplotlib.pyplot as plt
fig, ax = plt.subplots()
ax.scatter(-1, 0)
ax.text(-1, 0, 'Default blue')
ax.scatter(1, 0, c='tab:blue')
ax.text(1, 0, 'Also default blue')
ax.set_xlim(-2, 2)