Matplotlib 基于手动缩放的 x 轴缩放 y 轴 [英] Matplotlib scale y axis based on manually zoomed x axis

问题描述

我有很多在 x 轴上相关的数据，但都以非常不同的 Y 值为中心.x 上的数据也很长，因此很难看到细节.我希望能够为数据集手动设置 x 轴，然后让绘图根据位于手动设置的 x 轴内的数据点的值重新调整 y 轴本身.

I have a lot of data that is correlated on the x axis but are all center around very different Y values. The data is also very long on the x so its hard to see details. I want to be able to set the x axis manually for the data set and then have the plot rescale the y axis itself based on the values of the data points that lie inside that manually set x axis.

这可以用 matplotlib 实现吗?

Is this possible with matplotlib?

推荐答案

根据 mdurant 的评论，我写了一些最小的例子作为你的起点:

Based on the comment from mdurant I wrote some minimal example as a starting point for you:

import pylab as pl

pl.figure()
x = pl.rand(30)
x.sort()
y =  pl.sin(2 * pl.pi * x) + 0.1 * pl.randn(30)
pl.plot(x, y)

def ondraw(event):
    xlim = pl.gca().get_xlim()
    y_sel = y[pl.logical_and(x > xlim[0], x < xlim[1])]
    pl.gca().set_ylim((y_sel.min(), y_sel.max()))

pl.gcf().canvas.mpl_connect('draw_event', ondraw)

您可能想要添加更多事件来处理鼠标移动等.

You might want to add more events to handle mouse movements etc.

一些评论:

• 我正在使用 pylab，因为它提供了用于生成示例数据的有用函数.但是您也可以导入 matplotlib 库.
• ondraw 事件处理程序获取当前轴的当前 x 范围 gca()，选择具有相应 x 的 y 值 x 范围内的坐标，并设置由所选坐标的最小和最大 y 值确定的新 y 限制.
• 使用 mpl_connect，我们将事件处理程序附加到当前轴.每次绘制轴时 - 例如由于新的绘图命令或手动用户交互 - 它调用 ondraw 来更新 y 限制.

• I'm using pylab, since it provides useful functions for generating examle data. But you can import the matplotlib library as well.
• The ondraw event handler gets the current x limits of the current axes gca(), selects y values with corresponding x coordinates within the x limits and sets new y limits determined by the minimum and maximum y value of selected coordinates.
• With mpl_connect we attach the event handler to the current axes. Every time the axes is drawn - e.g. due to new plotting commands or manual user interaction - it calls ondraw to update the y limits.

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