防止熊猫df.plot（）对y轴排序

Question

Its very irritating that the pandas df.plot sorts the y-axis automatically in descending order.

df1[:10].plot(x="Term",y="P-value",kind='barh')

I do not want to sort anything in my data frame and plot as it is. Is there any way to prevent automatic sorting ?

I tried to look at documentation and the plot() does not have any option to prevent sorting. I tried in google but I could not find the solution.

Example file ( tab delimited ):

Term    p-value
De novo pyrimidine deoxyribonu  0.043726
Interleukin signaling pathway_  0.075241
Plasminogen activating cascade  0.099365
De novo purine biosynthesis_Ho  0.115435
Alzheimer disease-presenilin p  0.142836
Salvage pyrimidine ribonucleot  0.171718
Pyrimidine Metabolism_Homo sap  0.171718
Heterotrimeric G-protein signa  0.189208
p53 pathway_Homo sapiens_P0005  0.215917
Heterotrimeric G-protein signa  0.246512

Code snippet:

import matplotlib.pyplot as plt
import pandas as pd
df = pd.read_csv("test.txt",sep='\t')
df.plot(x="Term",y="p-value",kind='barh')
plt.show()

Answer 1

In [33]: df.plot.barh(x='Term',y="p-value")
Out[33]: <matplotlib.axes._subplots.AxesSubplot at 0xba4fb00>

In [34]: plt.gca().invert_yaxis()   # <--- this is the trick

In [35]: plt.tight_layout()

or manually reverting the 'Y-axis' data:

df.plot.barh(x=df.Term[::-1],y="p-value")
plt.tight_layout()

Result: