import matplotlib.pyplot as plt
import numpy as np



fig = plt.figure(figsize=(9, 6))
# 定義等高線高度函式
def f(x, y):
    return (pow(x,3)+pow(y,3)-15*x-20*y)+9

# 資料數目
n = 256
# 定義x, y
x = np.linspace(-5, 5, n)
y = np.linspace(-3, 2, n)

# 生成網格資料
X, Y = np.meshgrid(x, y)


# 填充等高線的顏色, 8是等高線分為幾部分
plt.contourf(X, Y, f(X, Y), 8, alpha = 0.75, cmap = plt.cm.prism)
# 繪製等高線
C = plt.contour(X, Y, f(X, Y), 8, colors = 'black', linewidth = 0.5)

#使得上面右邊都有刻度線，direction指明刻度線方向，可選out
plt.tick_params(right=True, top=True,labelsize=10, direction='in', pad=3, length=4)
x_ticks = np.linspace(5, -5, 8)#發現如果是np.arrange（5，-5,8）就不能畫上去
x_labels = ['1990', '1991', '1992', '1993', '1994', '1995','1996','1997']
y_ticks = np.linspace(-3, 2, 5)
y_labels = ['', '5', '10', '15', '20', '25']

#畫刻度線和xy軸的標籤
plt.xticks(x_ticks, x_labels, fontsize=9)
plt.yticks(y_ticks, y_labels, fontsize=9)

plt.show()
 

程式碼與圖片元素對應關係在註釋裡寫的很清楚哦