python中如何画火山图

1、导入数据

importpandasaspd#Dataanalysis
importnumpyasnp#Scientificcomputing
importseabornassns#Statisticalvisualization

#读取数据
df=pd.read_csv('./dataset_volcano.txt',sep='\t')
result=pd.DataFrame()
result['x']=df['logFC']
result['y']=df['P.Value']
result['-log10(pvalue)']=-df['P.Value'].apply(np.log10)

2、设置阈值

#设置pvalue和logFC的阈值
cut_off_pvalue=0.0000001
cut_off_logFC=1

3、设置分组

#分组为up,normal,down
result.loc[(result.x>cut_off_logFC)&(result.y<cut_off_pvalue),'group']='up'
result.loc[(result.x<-cut_off_logFC)&(result.y<cut_off_pvalue),'group']='down'
result.loc[(result.x>=-cut_off_logFC)&(result.x<=cut_off_logFC)|(result.y>=cut_off_pvalue),'group']='normal'

4、绘制散点图

#绘制散点图
ax=sns.scatterplot(x="x",y="-log10(pvalue)",
hue='group',
hue_order=('down','normal','up'),
palette=("#377EB8","grey","#E41A1C"),
alpha=0.5,
s=15,

5、设置散点图

#确定坐标轴显示范围
xmin=-6
xmax=10
ymin=7
ymax=13
ax.spines['right'].set_visible(False)#去掉右边框
ax.spines['top'].set_visible(False)#去掉上边框
ax.vlines(-cut_off_logFC,ymin,ymax,color='dimgrey',linestyle='dashed',linewidth=1)#画竖直线
ax.vlines(cut_off_logFC,ymin,ymax,color='dimgrey',linestyle='dashed',linewidth=1)#画竖直线
ax.hlines(-np.log10(cut_off_pvalue),xmin,xmax,color='dimgrey',linestyle='dashed',linewidth=1)#画竖水平线
ax.set_xticks(range(xmin,xmax,4))#设置x轴刻度
ax.set_yticks(range(ymin,ymax,2))#设置y轴刻度
ax.set_ylabel('-log10(pvalue)',fontweight='bold')#设置y轴标签
ax.set_xlabel('log2(foldchange)',fontweight='bold')#设置x轴标签