Plot 和从数据帧绘制的两条曲线之间的交点的返回点

Question

I am kind of new to coding and am currently trying to figure out how to find out the point of intersection of two curves plotted from dataframes.

The curves are:

This is the code I have right now.

GZ_positive = data.loc[data["GZ"] >= 0] 

x_new = GZ_positive['heel']
y_new = GZ_positive['GZ']


wind_heeling = pd.read_csv('wind_heeling.csv')  

GZ_positive['GZ'] = GZ_positive['GZ']/13400
wind_heeling['GZ_wind'] = wind_heeling['GZ_wind']/13400

x_wind = wind_heeling['Heel']
y_wind = wind_heeling['GZ_wind']

plt.figure()
plt.plot(x_new,y_new)
plt.plot(x_wind,y_wind)
plt.grid(True)
plt.show()

I would then like to drop all the points of the orange line before and after the points of intersection. The aim of this analysis is to calculate the area under the orange graph but between the points where it intersects the blue graph:

.

Have found a few similar problems online but nothing seems to work (or I have done it wrong). Would appreciate it if anyone could point me in the right direction. Thanks!

Answer 1

You can define two new curves. One will be given by the pointwise minimum of your two curves, the other will be a horizontal line at zero. Now, you can use the fill_between method from matplotlib . Here is an example:

xs = np.linspace(0, 10, 100)
ys = -xs**2 - 4 + 10*xs

df = pd.DataFrame({
    "one": 5,
    "two": ys,
})

ax = df.plot()
ax.set_ylim(0, 30)

upper = df.min(1)
lower = np.zeros(df.shape[0])

ax.fill_between(df.index, lower, upper)