如何在matplotlib中将图例添加到imshow() [英] How to add legend to imshow() in matplotlib

问题描述

我正在使用matplotlib

在plot()或bar()中，如果我们向其添加标签，则可以轻松放置图例.但是如果是contourf()或imshow()

怎么办

我知道有一个colorbar()可以显示颜色范围，但是不满意.我想要一个带有名称(标签)的图例.

我能想到的是，在矩阵中的每个元素上添加标签，然后尝试legend()来查看其是否有效，但是如何在标签上像值一样添加标签? >

在我的情况下，原始数据如下:

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" ...依此类推. imshow()非常适合我的情况，但没有图例.

我的问题是:

1. 是否有一个可以自动添加图例的函数，例如，就我而言，我只需要这样做:someFunction('grass'，'sand'，...)

2. 如果没有，如何将标签添加到矩阵中的每个值.例如，将矩阵1中的所有1标记为草"，将矩阵2中的所有2标记为沙" ...等等.

谢谢！

修改:

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

解决方案

我想您必须伪造您的图例，因为创建图例需要一行代码.

您可以执行以下操作:

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.但是也许您可以在此基础上构建一些东西.

I am using matplotlib

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

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).

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??

in my case, the raw data is like:

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

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

my question is:

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',...)

2. 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.

Thank you!

Edit:

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

解决方案

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

You can do something like this:

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()

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

[edit: added missing parenthesis]

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