gnuplot：在一列中用基于颜色的值绘制点 [英] gnuplot: plotting points with color based values in one column

问题描述

我想绘制分类结果并标记真正的类。所以，基本上我需要的是为字符串列中的值为每个点分配一个颜色。

数据集看起来像这样：

lockquote
5.1 3.5 1.4 0.2 Iris-setosa

结束了脚本解决方案（感谢这里的答案：。

使用数据文件 Data.csv ：

  5.4452 4.6816蓝色
 1.2079 9.4082红色
 7.4732 6.5507红色
 2.3329 8.2996红色
 3.4535 2.1937绿色
 1.7909 2.5173绿色
 2.5383 7.9700蓝色
   
 
 $ b 
以及此脚本：
 
 
  set pointsize 3 
 plot。
 
I would like to plot results of classification and mark true classes. So, basically what I need is to assign a color for each point base on value in a string column. 

dataset looks like this:

  
5.1   3.5 1.4 0.2 Iris-setosa
I ended up with script following solution (thanks to the answer in here: How to make points one color when a third column equals zero, and another color otherwise, in Gnuplot?)
set palette model RGB defined (0 "red",1 "blue", 2 "green")
plot 'iris.data' using 1:2:5 notitle with points pt 2 palette
in the original dataset I replaced string labels with numbers, because I don't know how to work with strings in gnuplot. Is there a way how to map string to colors?

Currently the output looks like this:


However I don't like the gradient palette because it doesn't make sense in this case. I would prefer normal legend with a single color and name of the class. Any idea how to do that?
解决方案
A way how you could do that is by using awk.

Using a data file Data.csv:
5.4452 4.6816 blue
1.2079 9.4082 red
7.4732 6.5507 red
2.3329 8.2996 red
3.4535 2.1937 green
1.7909 2.5173 green
2.5383 7.9700 blue
and this script:
set pointsize 3
plot "< awk '{if($3 == \"red\") print}' Data.csv" u 1:2 t "red" w p pt 2, \
     "< awk '{if($3 == \"green\") print}' Data.csv" u 1:2 t "green" w p pt 2, \
     "< awk '{if($3 == \"blue\") print}' Data.csv" u 1:2 t "blue" w p pt 2
you get this plot:



What awk does is simply check the third parameter of the data file and only print the line if it has some value: like red or blue.

You would also get rid of the palette with the gradient.

The script could be further improved by using gnuplot iterations.

                        
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