1 import matplotlib.pyplot as plt 2 import numpy as np 3 4 x = np.linspace(-3, 3, 50) 5 y1 = 2 * x + 1 6 y2 = x ** 2 7 8 plt.figure() 9 l1, = plt.plot(x, y1, color = "red", linewidth = 5.0, linestyle = '--', label = 'down') #指定線的顏色, 寬度和類型 10 l2, = plt.plot(x, y2, label = "up") 11 12 #給figure添加legend（圖例、說明、解釋） 13 plt.legend(handles = [l1, l2], labels = ["y1 = 2 * x + 1", "y2 = x ** 2"], loc = "best") 14 15 plt.show()
1 import matplotlib.pyplot as plt 2 import numpy as np 3 4 x = np.linspace(-3, 3, 50) 5 y1 = 2 * x + 1 6 X0 =1 7 Y0 = 2 * X0 + 1 8 9 #figure 1 10 plt.figure() 11 plt.plot(x, y1) 12 plt.scatter(X0, Y0, s = 30, color = 'black') #在數據線上畫點 13 plt.plot([X0, X0], [Y0, 0], color = "black", linewidth = 3.0, linestyle = '--') #過一點做垂直於X軸的垂線 14 15 #坐標軸的移動 gca = “get current axis” 16 ax = plt.gca() 17 ax.spines["right"].set_color("none") 18 ax.spines["top"].set_color("none") 19 ax.xaxis.set_ticks_position("bottom") 20 ax.yaxis.set_ticks_position("left") 21 ax.spines["bottom"].set_position(("data", 0)) #Set the X and Y coordinates of the sprite simultaneously 22 ax.spines["left"].set_position(("data", 0)) 23 24 25 #在figure上做標注的兩種方法 26 #方法一 27 #關於annotate的相關參數介紹，參考博文 https://blog.csdn.net/leaf_zizi/article/details/82886755 28 ########################## 29 plt.annotate(r"$2*x_0 + 1 = %s$"%Y0, xy = (X0, Y0), xytext = (+30, -30), 30 textcoords = "offset points", fontsize = 16, 31 arrowprops = dict(arrowstyle = "->", connectionstyle = "arc3, rad=.2")) 32 #方法二 33 #補充：關於下角標的添加 “_+下角標字母” 34 #關於text的相關參數介紹，參考博文 https://blog.csdn.net/TeFuirnever/article/details/88947248 35 ########################## 36 plt.text(-3.7, 3, r"$This\ is\ y1 = 2 * x + 1\ \mu\ \sigma_i\ \alpha_t$", 37 fontdict={"size":16, "color":"red"}) 38 39 plt.show()