如何在 python matplotlib 中为 pcolor 设置固定颜色条？

发布于 2024-09-05 03:26:25 字数 779 浏览 0 评论 0原文

我使用 pcolor 和自定义颜色图来绘制值矩阵。我设置了颜色图，使低值是白色，高值是红色，如下所示。我所有矩阵的值都在 0 到 20（含）之间，我希望 20 始终为纯红色，0 始终为纯白色，即使矩阵的值不跨越整个范围。例如，如果我的矩阵只有 2 到 7 之间的值，我不希望它将 2 绘制为白色，将 7 绘制为红色，而是将其着色，就好像范围仍然是 0 到 20 一样。我该怎么做？我尝试使用 colorbar 的“ticks=”选项，但它不起作用。

这是我当前的代码（假设“my_matrix”包含要绘制的值）：

cdict = {'red': ((0.0, 1.0, 1.0),
         (0.5, 1.0, 1.0),
         (1.0, 1.0, 1.0)),
     'green': ((0.0, 1.0, 1.0),
           (0.5, 1.0, 1.0),
           (1.0, 0.0, 0.0)),
     'blue': ((0.0, 1.0, 1.0),
          (0.5, 1.0, 1.0),
          (1.0, 0.0, 0.0))}
my_cmap = matplotlib.colors.LinearSegmentedColormap('my_colormap', cdict, 256)
colored_matrix = plt.pcolor(my_matrix, cmap=my_cmap)
plt.colorbar(colored_matrix, ticks=[0, 5, 10, 15, 20])

知道如何修复此问题以获得正确的结果吗？非常感谢。

原文

I am using pcolor with a custom color map to plot a matrix of values. I set my color map so that low values are white and high values are red, as shown below. All of my matrices have values between 0 and 20 (inclusive) and I'd like 20 to always be pure red and 0 to always be pure white, even if the matrix has values that don't span the entire range. For example, if my matrix only has values between 2 and 7, I don't want it to plot 2 as white and 7 as red, but rather color it as if the range is still 0 to 20. How can I do this? I tried using the "ticks=" option of colorbar but it did not work.

Here is my current code (assume "my_matrix" contains the values to be plotted):

cdict = {'red': ((0.0, 1.0, 1.0),
         (0.5, 1.0, 1.0),
         (1.0, 1.0, 1.0)),
     'green': ((0.0, 1.0, 1.0),
           (0.5, 1.0, 1.0),
           (1.0, 0.0, 0.0)),
     'blue': ((0.0, 1.0, 1.0),
          (0.5, 1.0, 1.0),
          (1.0, 0.0, 0.0))}
my_cmap = matplotlib.colors.LinearSegmentedColormap('my_colormap', cdict, 256)
colored_matrix = plt.pcolor(my_matrix, cmap=my_cmap)
plt.colorbar(colored_matrix, ticks=[0, 5, 10, 15, 20])

any idea how I can fix this to get the right result? thanks very much.

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