Matplotlib标准化颜色条(Python) [英] Matplotlib normalize colorbar (Python)

问题描述

我正在尝试使用matplotlib(当然还有numpy)绘制轮廓线图.它可以正常工作，可以绘制应绘制的图，但是很遗憾，我无法设置颜色栏范围.问题是我有很多图，需要所有图都具有相同的颜色条(相同的最小和最大值，相同的颜色).我复制并粘贴了我在互联网上找到的几乎所有代码段，但均未成功.到目前为止，我的代码:

I'm trying to plot a contourf-plot using matplotlib (and numpy of course). And it works, it plots what it should plot, but unfortunatelly I cannot set the colorbar range. The problem is that I have a plenty of plots and need all of them to have the same colorbar (same min and max, same colors). I copy&past-ed almost every code snippet I found on the internet, but without success. My code so far:

    import numpy as np;
    import matplotlib as mpl;
    import matplotlib.pyplot as plt;
    [...]
    plotFreq, plotCoord = np.meshgrid(plotFreqVect, plotCoordVect);

    figHandler = plt.figure();
    cont_PSD = plt.contourf(plotFreq, plotCoord, plotPxx, 200, linestyle=None);


    normi = mpl.colors.Normalize(vmin=-80, vmax=20);

    colbar_PSD = plt.colorbar(cont_PSD);
    colbar_PSD.set_norm(normi);
    #colbar_PSD.norm = normi;
    #mpl.colors.Normalize(vmin=-80, vmax=20);

    plt.axis([1, 1000, -400, 400]);

如您所见，colorbar规范有三行不同，它们都不起作用.范围仍然是自动设置的...我的意思是其他所有东西都在起作用，为什么不显示颜色栏?我什至没有收到错误或警告.

As you can see there are three different lines for the colorbar norm, none of them is working. The range is still set automatically... I mean everything else is working, why not the colorbar? I don't even get errors or warnings.

谢谢，itpdg

图片，带有plt.clim(-80,20):

EDIT 1: Pictures, with plt.clim(-80,20):

推荐答案

我前一段时间遇到了这个问题，并认为这是一个错误(请参阅

I ran into this issue a while back and thought it was a bug (see MPL issue #5055). It's not, but it does require using the extend kwarg, which was non-intuitive to me. Here's what you want to do:

normi = mpl.colors.Normalize(vmin=-80, vmax=20)

cont_PSD = plt.contourf(plotFreq, plotCoord, plotPxx,
                        np.linspace(-80, 20, 200),
                        linestyle=None,
                        norm=normi, extend='both')

plt.colorbar(colbar_PSD)

您可以取消 plt.clim ， colbar_PSD.set_norm 和其他类似调用.

You can do-away with the plt.clim, colbar_PSD.set_norm and other similar calls.

在此处，可以找到有关 extend = 的更多示例用法.

More examples uses of extend= are available here.

请注意，这将创建一个在顶部和底部带有三角形"的颜色条，表明数据超出了颜色条，但是我认为一旦习惯了它们，它们就会具有描述性.

Note that this will create a colorbar with 'triangles' at the top and bottom indicating that the data extends beyond the colorbar, but I think you'll like them once you get used to them, they are descriptive.

祝你好运！

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