问题描述
我有一个图，我想在图上标记 x 的一些值，如下图所示，(p.s. 我手工放置了点)看剧情
I have a plot that I want to mark some values of x on the graph like in the following image, (p.s. I put the dots by hand)see the plot
我尝试了以下代码，但没有按预期工作.
I tried the following code, yet it did not work as I have expected.
roots = [-1,1,2]
plt.plot(vals,poly,markevery=roots,label='some graph')
我想我在上面发布的图片有问题；作为总结，我想在函数行上放一个点，表示该点是根.
I guess something wrong with the image I tried to post above; as a wrap up, I want to put a dot, on the function line which indicates that point is the root.
推荐答案
假设 vals 是 [-60,60] 范围内的整数，人们会需要在该列表中找到 [-1,1,2] 的位置，并将这些位置用作 markevery 的参数.
Assuming that the vals are integers in the range of [-60,60], one would need to find the positions of [-1,1,2] in that list and use those positions as the argument to markevery.
import matplotlib.pyplot as plt
vals,poly = range(-60,60), range(-60,60)
plt.plot(vals, poly, label='some graph')
roots = [-1,1,2]
mark = [vals.index(i) for i in roots]
print(mark)
plt.plot(vals,poly,markevery=mark, ls="", marker="o", label="points")
plt.show()
或者，您也可以只绘制这些值，
Alternatively, you could also just plot only those values,
import matplotlib.pyplot as plt
vals,poly = range(-60,60), range(-60,60)
plt.plot(vals, poly, label='some graph')
roots = [-1,1,2]
mark = [vals.index(i) for i in roots]
plt.plot(roots,[poly[i] for i in mark], ls="", marker="o", label="points")
plt.show()
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