修改一行中的y数据 [英] Modify y data in a line

问题描述

我有以下脚本

import matplotlib.pyplot as plt                                                  

x = [1, 2, 3, 4, 5] 
fig, ax = plt.subplots() 
# draw a horizontal line y=0
line, = ax.plot(x, [0 for _ in x]) 
def mod_ydata(ev): 
    X = ev.xdata 
    if X is not None: 
        n = round(X) 
        line.set_ydata([n for _ in x]) 
        fig.canvas.draw_idle() 
fig.canvas.mpl_connect('button_press_event', mod_ydata)                          
plt.show()

• 预期行为原始水平线 y = 0 被清除以响应鼠标点击和新的水平线 y = i>圆形(x)绘制，其中x是鼠标点击的横坐标.

  • Expected Behavior the original horizontal line y = 0 is cleared in response to a mouse click and a new horizontal line, y = round(x) is drawn, where x is the abscissa of the mouse click.

    意外行为已清除原始水平线，并且未绘制新的水平线.

    Unexpected Behavior the original horizontal line is cleared and no new horizontal line is drawn.

    我使用 line.get_ydata() 检查了交互式 IPython 终端，回调确实更新了纵坐标.

    I checked in an interactive IPython terminal, using line.get_ydata(), that the callback does update the ordinates.

    我不得不说我玩过 plt.ion()，在回调中重复 plt.show()，使用 a1.draw() 等总是无济于事.

    I have to say that I've played with plt.ion(), repeating plt.show() in the callback, using a1.draw(), etc always to no avail.

    我知道我可能遗漏了显而易见的东西，但我在这里......

    I understand that I'm probably missing the obvious, but here I am...

    推荐答案

    您的代码运行良好，只是在可见 y 限制之外绘制了线条.

    Your code is working fine, it's just drawing the line outside of the visible y-limits.

    • 或者您事先强制执行适当的 y 限制(例如，在 plt.show() 之前使用 ax.set_ylim(-1,5))
    • 或在调用 fig.canvas.draw_idle()之前的 mod_ydata()中添加以下几行:
    • either you enforce proper y-limits beforehand (e.g. using ax.set_ylim(-1,5) before plt.show())
    • or you add the following lines inside mod_ydata(), right before the call to fig.canvas.draw_idle():

    ax.relim()
    ax.autoscale_view()
    

    尽管后者使线条的运动"有点难以看到.

    although the latter makes the "movement" of the line kind of hard to see.

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