如何在 matplotlib 中向 im​​show() 添加图例 [英] How to add legend to imshow() in matplotlib

问题描述

我正在使用 matplotlib

在 plot() 或 bar() 中，如果我们给它们添加标签，我们可以很容易地放置图例.但如果它是 contourf() 或 imshow()

In plot() or bar(), we can easily put legend, if we add labels to them. but what if it is a contourf() or imshow()

我知道有一个colorbar()可以呈现颜色范围，但是不满意.我想要这样一个有名字(标签)的传说.

I know there is a colorbar() which can present the color range, but it is not satisfied. I want such a legend which have names(labels).

我能想到的是，给矩阵中的每个元素添加标签，然后，尝试legend()，看看它是否有效，但是如何给元素添加标签，比如一个值??

For what I can think of is that, add labels to each element in the matrix, then ,try legend(), to see if it works, but how to add label to the element, like a value??

就我而言，原始数据如下:

in my case, the raw data is like:

1,2,3,3,4
2,3,4,4,5
1,1,1,2,2

例如，1 代表草"，2 代表沙"，3 代表山"……以此类推.imshow() 非常适合我的情况，但没有图例.

for example, 1 represents 'grass', 2 represents 'sand', 3 represents 'hill'... and so on. imshow() works perfectly with my case, but without the legend.

我的问题是:

1. 有没有可以自动添加图例的函数，比如我的情况，我只需要这样:someFunction('grass','sand',...)

1. Is there a function that can automatically add legend, for example, in my case, I just have to do like this: someFunction('grass','sand',...)

如果没有，如何为矩阵中的每个值添加标签.例如，将矩阵草"中的所有 1 标记，将矩阵沙"中的所有 2 标记......等等.

If there isn't, how do I add labels to each value in the matrix. For example, label all the 1 in the matrix 'grass', labell all the 2 in the matrix 'sand'...and so on.

谢谢！

编辑:

感谢@dnalow，它真的很聪明.但是，我仍然想知道是否有任何正式的解决方案.

Thanks to @dnalow, it's smart really. However, I still wonder if there is any formal solution.

推荐答案

我猜你必须伪造你的图例，因为它需要一行来创建图例.

I guess you have to fake your legend, since it requires a line for creating the legend.

你可以这样做:

import pylab as pl
mycmap = pl.cm.jet # for example
for entry in pl.unique(raw_data):
    mycolor = mycmap(entry*255/(max(raw_data) - min(raw_data)))
    pl.plot(0, 0, "-", c=mycolor, label=mynames[entry])

pl.imshow(raw_data)
pl.legend()

当然，这还不是很令人满意.但也许你可以在此基础上构建一些东西.

Of cause this is not very satisfying yet. But maybe you can build something on that.

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