Python绘图并标记出指定点(最大值点)方法实例

import numpy as np
import matplotlib.pyplot as plt
 
# 生成数据，这里生成一个正弦曲线
x = np.linspace(-5, 5, 100)  # 在[-5,5]之间生成100个点作为x坐标
y = np.sin(x)               # 计算每个x点上的正弦值
 
# 找到最大值点，这里使用np.argmax函数查找y数组中的最大值的索引
max_idx = np.argmax(y)
max_x, max_y = x[max_idx], y[max_idx]
 
# 绘制图形
plt.plot(x, y)              # 绘制正弦曲线
plt.scatter(max_x, max_y, color='red', s=50)  # 在最大值点上绘制一个红色的圆点
plt.annotate(f'max: ({max_x:.2f}, {max_y:.2f})', xy=(max_x, max_y), xytext=(max_x-1, max_y+0.5),
             arrowprops=dict(facecolor='red', shrink=0.05))  # 添加注释，使用红色箭头连接注释和最大值点
plt.show()                  # 显示图形

import matplotlib.pyplot as plt
import numpy as np

def demo_test():
    a=np.array([0.15,0.16,0.14,0.17,0.12,0.16,0.1,0.08,0.05,0.07,0.06]);
    max_indx=np.argmax(a)#max value index
    min_indx=np.argmin(a)#min value index
    plt.plot(a,'r-o')
    plt.plot(max_indx,a[max_indx],'ks')
    show_max='['+str(max_indx)+' '+str(a[max_indx])+']'
    plt.annotate(show_max,xytext=(max_indx,a[max_indx]),xy=(max_indx,a[max_indx]))
    plt.plot(min_indx,a[min_indx],'gs')
    plt.show()

if __name__=="__main__":
    demo_test();