如何在循环中的某些xy值处自动注释点或线

Question

嗨，我成功地从excel数据中使用for in-loop创建了多个压力和温度等图形，并生成了多个png文件。我把脚本附在下面

在230℃的温度与温度线图（蓝色虚线）相交的地方，是否可以自动创建一条线或注释（红色划痕）

import pandas as pd
import matplotlib.pyplot as plt
import numpy as np

path ='F:\Backup\JN\TOR\TOR HLS py.xlsx'
data= pd.ExcelFile(path)

sheets = data.sheet_names
well = ''

for i in sheets:
    well=pd.read_excel(data, sheet_name=i)
    fig=plt.figure(figsize=(8,12), constrained_layout='True')
    plt.plot(well['x csg'], well['mdpl csg'], marker='s', linestyle='solid', color='black')
    plt.plot(well['x liner'], well['mdpl liner'], marker='s', linestyle='dotted', color='black')
    plt.plot(well['T'], well['mdpl pt'], marker='o', color='blue', label='Temperature')
    plt.plot(well['P'], well['mdpl pt'], marker='o', color='crimson', label='Pressure')
    for x, txt in enumerate(well['csg']):
        plt.annotate(txt, ((well['x csg']+5)[x], well['mdpl csg'][x]), size=8)
    for y, txt in enumerate(well['liner']):
        plt.annotate(txt, ((well['x liner']+5)[y], well['mdpl liner'][y]), size=8)
    plt.savefig(str(i), dpi=300, transparent='True')
    plt.close(i)

请帮忙，谢谢

Answer 1

我只是从x中找到插值的y值，然后用直线注释插值的y值

y230=float(np.interp(xval, well['T'], well['mdpl pt']))
if math.isnan(y230) == False:
    plt.annotate('ToR 230 $^o$C', xy=(200, y230), xytext=(250, (y230-9)), 
    arrowprops=dict(color='green', arrowstyle="-", lw=2))

Answer 2

请检查代码片段。我建议您使用shapely库来计算两条线之间的交点。如果路径不使用相同的X轴值，此方法也有效。您将获得可以使用循环注释的交点。

from matplotlib import pyplot as plt
import numpy as np
import shapely
from shapely.geometry import LineString, Point

x = np.linspace(0, 5, 20)
y1 = x**2
y2 = 3*x

za1=[(i,j) for i,j in zip(x,y1)]    #points for (x,y) line1
za2=[(i,j) for i,j in zip(x,y2)]    #points for (x,y) line2

line1 = LineString(za1)
line2 = LineString(za2)

intersection = line1.intersection(line2)
intersect_points = [list(p.coords)[0] for p in intersection]
print(intersect_points)
#[(0.0, 0.0), (2.994555353901996, 8.983666061705987)]     point of intersection

fig, ax = plt.subplots()
plt.plot(x, y1, color='lightcoral')
plt.plot(x, y2, color='#4b0082')

for i in intersect_points:
  ax.annotate('x',xy=(i),fontsize=20,color='red')
plt.show()

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