matplotlib.pyplot.plot 只给了两个节点不给线，这是为什么呢？

Question

I'm trying to draw a line between 2 nodes (x1=130, y1=130) and (x2=202, y2=202)

this code works well

coor = np.array([[130,202],[130,202]])
_ = plt.plot(coor[0],coor[1])

and I got

However, the following code coming from the matplotlib doc , does not work as stated there

plt.plot(130, 130,'g^', 202, 202, 'r^')

which just gives two nodes without giving the line, why is that?

Answer 1

This is because in the matplotlib docs, in plot(x1, y1, 'g^', x2, y2, 'g-') , x1 , y1 , x2 and y2 are assumed to be different data sets , ie arrays consisting of multiple points.

In this case, you'd get a plot of x1 vs y1 with green triangles and a green line connecting the points of x2 vs y2 .

But you won't have a line connecting x1:y1 to x2:y2 .

Also you probably meant to write plt.plot(130, 130,'g^', 202, 202, 'r-') (note the minus instead of the ^ ).

So eg this will work:

plt.plot([1, 2], [3, 4],'g^', [5, 6], [7, 8], '^-')