Different colors for points and line in Seaborn re

问题:

All examples listed in Seaborn's regplot documentation show the same color for dots and the regression line. Changing the color argument changes both. How can one set a different color for the points as the line?

回答1:

You are right in that the color argument changes all the plot elements. However, if you read the last bit of the relevant sentence in the documentation:

color : matplotlib color

Color to apply to all plot elements; will be superseded by colors passed in scatter_kws or line_kws.

Therefore, using scatter_kws or line_kws we can change the color of them individually. Taking the first example given in the documentation:

import seaborn as sns

tips = sns.load_dataset("tips")
ax = sns.regplot(x="total_bill", y="tip", data=tips,
                 scatter_kws={"color": "black"}, line_kws={"color": "red"})

plt.show()

Gives:

回答2:

You already have a good answer. DavidG's suggestion to use line_kws and scatter_kws has the side-effect that the regression line and the confidence interval colors are the same (though the ci is alpha-ed). Here is a way to have distinct colors. If there's a better way, I'd like to know!

Create a seaborn FacetGrid, then add layers with the map() function:

import pandas 
x = [5, 3, 6, 3, 4, 4, 6, 8]
y = [13, 15, 7, 12, 13, 11, 9, 5]
d = pandas.DataFrame({'x':x, 'y': y})
import seaborn
import matplotlib.pyplot as plt 
seaborn.set(style = 'whitegrid')
p = seaborn.FacetGrid(d, size = 4, aspect = 1.5) 
p.map(plt.scatter, 'x', 'y', color = 'red')
p.map(seaborn.regplot, 'x', 'y', scatter = False, ci = 95, 
    fit_reg = True, color = 'blue') 
p.map(seaborn.regplot, 'x', 'y', scatter = False, ci = 0, 
    fit_reg = True, color = 'darkgreen')
p.set(xlim = (2, 9)) 
p.set(ylim = (2, 17)) 
p.savefig('xy-regression-ci.pdf', bbox_inches='tight')

I was inspired by this question

Remark in passing (off topic): set the size of the figure early on, because usual methods don't seem to apply here.

# set figure size here by combining size and aspect:
seaborn.FacetGrid(d, size=4, aspect=1.5) 

# usual tricks below do not work with FacetGrid?
p.set_size_inches(8,4)
seaborn.set(rc={'figure.figsize':(8,4)})
rcParams['figure.figsize'] = 8,4