Seaborn Distplot 下的不同阴影

Question

I'm trying to create plot with shadings which are based on this MIC(1) line. Different shading above than beneath.

from scipy import stats
import numpy as np
import matplotlib.pyplot as plt
import seaborn as sns

def createSkewDist(mean, sd, skew, size):

    # calculate the degrees of freedom 1 required to obtain the specific skewness statistic, derived from simulations
    loglog_slope=-2.211897875506251 
    loglog_intercept=1.002555437670879 
    df2=500
    df1 = 10**(loglog_slope*np.log10(abs(skew)) + loglog_intercept)

    # sample from F distribution
    fsample = np.sort(stats.f(df1, df2).rvs(size=size))

    # adjust the variance by scaling the distance from each point to the distribution mean by a constant, derived from simulations
    k1_slope = 0.5670830069364579
    k1_intercept = -0.09239985798819927
    k2_slope = 0.5823114978219056
    k2_intercept = -0.11748300123471256

    scaling_slope = abs(skew)*k1_slope + k1_intercept
    scaling_intercept = abs(skew)*k2_slope + k2_intercept

    scale_factor = (sd - scaling_intercept)/scaling_slope    
    new_dist = (fsample - np.mean(fsample))*scale_factor + fsample

    # flip the distribution if specified skew is negative
    if skew < 0:
        new_dist = np.mean(new_dist) - new_dist

    # adjust the distribution mean to the specified value
    final_dist = new_dist + (mean - np.mean(new_dist))

    return final_dist



desired_mean = 30
desired_skew = 1.5
desired_sd = 20

final_dist = createSkewDist(mean=desired_mean, sd=desired_sd, skew=desired_skew, size=1000000)

# inspect the plots & moments, try random sample
fig, ax = plt.subplots(figsize=(12,7))
sns.distplot(final_dist, 
             hist=False, 
             ax=ax, 
             color='darkred', 
             kde_kws=dict(linewidth=4))

l1 = ax.lines[0]


# Get the xy data from the lines so that we can shade
x1 = l1.get_xydata()[:,0]
x1[0] = 0

y1 = l1.get_xydata()[:,1]
y1[0] = 0

ax.fill_between(x1,y1, color="lemonchiffon", alpha=0.3)


ax.set_ylim(0.0001,0.03)
ax.axhline(0.002, ls="--")
ax.set_xlim(1.5, 200)
ax.set_yticklabels([])
ax.set_xticklabels([])


trans = transforms.blended_transform_factory(
    ax.get_yticklabels()[0].get_transform(), ax.transData)

ax.text(0,0.0025, "{}".format("MIC(1) = 1"), color="blue", transform=trans, 
        ha="right", va="top", fontsize = 12)



trans_2 = transforms.blended_transform_factory(
    ax.get_xticklabels()[0].get_transform(), ax.transData)

ax.text(84,0, "{}".format("\n84"), color="darkred", transform=trans_2, 
        ha="center", va="top", fontsize = 12)

ax.text(1.5,0, "{}".format("\n0"), color="darkred", transform=trans_2, 
        ha="center", va="top", fontsize = 12)


ax.axvline(x = 84, ymin = 0, ymax = 0.03, ls = '--', color = 'darkred' )


ax.set_yticks([])
ax.set_xticks([])

ax.spines['top'].set_color(None)
ax.spines['right'].set_color(None)
ax.spines['left'].set_linewidth(2)
ax.spines['bottom'].set_linewidth(2)
ax.set_ylabel("Concentration [mg/L]", labelpad = 80, fontsize = 15)
ax.set_xlabel("Time [h]", labelpad = 80, fontsize = 15)
ax.set_title("AUC/MIC", fontsize = 20, pad = 30)


plt.annotate("AUC/MIC", 
             xy=(18, 0.02), 
             xytext=(18, 0.03), 
             arrowprops=dict(arrowstyle="->"), fontsize = 12);

;

That's what I have:

And that's what I'd like to have (it's done in paint, so forgive me :) ):

I was experimenting with fill_between and fill_betweenx. However, without any satisfying results. Definitely, run out of ideas. I'd really appreciate any help on this. Best wishes!

Answer 1

Your fill_between works as expected. The problem is that color="lemonchiffon" with alpha=0.3 is barely visible. Try to use a brighter color and/or a higher value for alpha .

So, this colors the part of the graph between zero and the kde curve.

Now, to create a different coloring above and below the horizontal line, where= and np.minimum can be used in fill_between :

pos_hline = 0.002
ax.fill_between(x1, pos_hline, y1, color="yellow", alpha=0.3, where=y1 > pos_hline)
ax.fill_between(x1, 0, np.minimum(y1, pos_hline), color="blue", alpha=0.3)

Without where=y1 > pos_hline , fill_between would also color the region above the curve where the curve falls below that horizontal line.

PS: Note that sns.histplot has been deprecated since Seaborn version 0.11 . To only plot the kde curve, you can use sns.kdeplot :

sns.kdeplot(final_dist, ax=ax, color='darkred', linewidth=4)