直接从文本文件绘图功能 [英] Plotting a function directly from a text file

问题描述

有没有一种方法来绘制基于价值观从一个文本文件中的函数？

Is there a way to plot a function based on values from a text file?

我知道如何定义gnuplot的一个函数，然后绘制它，但是这不是我所需要的。
我有与该定期更新功能常数表。当这种情况发生更新我希望能够运行，吸引了这种新的曲线的图形脚本。由于有相当一些数字得出我要自动运行的程序。

I know how to define a function in gnuplot and then plot it but that is not what I need. I have a table with constants for functions that are updated regularly. When this update happens I want to be able to run a script that draws a figure with this new curve. Since there are quite few figures to draw I want to automate the procedure.

下面是常量的示例表：

location a  b  c
1        1  3  4
2

有两种方式我看到解决这个问题，但我不知道是否以及如何实施。

There are two ways I see to solve the problem but I do not know if and how they can be implemented.

1. 然后我可以使用awk来生成字符串： F（X）= 1（X）** 2 + 3（X）+4 ，将其写入文件，并以某种方式使gnuplot的阅读一定 X 系列。
这个新文件和剧情

2. 或使用的gnuplot里面的东西AWK像 F（X）= AWK / 1 / {打印F（X）=$ 2 等，或AWK直接使用plot命令。

1. I can then use awk to produce the string: f(x)=1(x)**2+3(x)+4, write it to a file and somehow make gnuplot read this new file and plot on a certain x range.
2. or use awk inside gnuplot something like f(x) = awk /1/ {print "f(x)="$2 etc., or use awk directly in the plot command.

我任何情况下，我坚持，并没有找到一个解决这个问题的在线，你有什么建议吗？

I any case, I'm stuck and have not found a solution to this problem online, do you have any suggestions?

推荐答案

另外possibilty有这几分通用版本，你可以做到以下几点：

Another possibilty to have a somewhat generic version for this, you can do the following:

假设，所述参数被存储在一个文件中 parameters.dat 与含有变量名的第一行和所有其他的参数集，如

Assume, the parameters are stored in a file parameters.dat with the first line containing the variable names and all others the parameter sets, like

location a b c
1        1 3 4

该脚本文件是这样的：

The script file looks like this:

file = 'parameters.dat'
par_names = system('head -1 '.file)
par_cnt = words(par_names)

# which parameter set to choose
par_line_num = 2
# select the respective string
par_line = system(sprintf('head -%d ', par_line_num).file.' | tail -1')
par_string = ''
do for [i=1:par_cnt] {
  eval(word(par_names, i).' = '.word(par_line, i))
}
f(x) = a*x**2 + b*x + c

plot f(x) title sprintf('location = %d', location)

这篇关于直接从文本文件绘图功能的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！