在图形中注释兴趣点（Matplotlib）

Question

I want to annotate and draw a line at a point of interest in my graph. I have written a code for it, which does the work.

import numpy as np
import pandas as pd
import matplotlib.pyplot as plt
fsource=('/Users/Maxwell/Desktop/OES data.xlsx')
df=pd.read_excel(fsource,header = 1, parse_cols = "C:D",names=['Wavelength','Intensity'])
fig1 = plt.figure()
f, ax = plt.subplots(1, figsize = (8,4))
ax.set_xlabel('Wavelength',fontsize=15)
ax.set_ylabel('Intensity',fontsize=15)
ax.plot(df['Wavelength'],df['Intensity'],color='red')
ax.set_xlim(xmin=400,xmax=800)
ax.set_ylim(ymin=0,ymax=5000) #Specify the max and min of y axis
ax.tick_params(axis= 'both', labelsize=12) #fontsize of x & y ticks as 12
ax.axvline(x= 604,color='black',ymin=0.05, ymax=0.5) #x=604 is my point of interest.
ax.annotate('POF-1', xy=(604, 2400),fontsize=12)
plt.show()

I have some questions regarding this method/procedure:

1. Is there a more efficient/better way of doing the same work?(any refinements to code etc.)

2. My code works for only one point of interest 'POF-1'. If I have several points of interest, I will have to number them one by one and also specify the length of line again and again. What should I do to automate the task, such that annotation and lines appear at all points of interest at the same time?(for eg annotate points x=500, 730, 790 etc with some predefined text.)

The link for the raw file is OES data in the link

Answer 1

You may loop over the points to annotate:

xs = [500, 730, 790]
texts = ["POF-1", "Some peak", "another peak"]
for x, t in zip(xs, texts):
    ax.axvline(x=x, color='black',ymin=0.05, ymax=0.5)
    ax.annotate(t, xy=(x, 2400),fontsize=12)