Re: [Gnuplot-info] Plotting multiple columns from stdin

[<br...@ph...>]

Bennett, Silas (GE Infrastructure) wrote:
>> gnuplot> plot "-" using 1:2 with lines, "" using 1:3 with lines ^ 
>> line 7: no data point found in specified file

> Is this a feature or a bug?

A feature.  Of your command script as much as of gnuplot

The problem is that you're trying to read the same inline data set
twice. That's not how inline data work.  You would have to split you
your multi-column data into separate datasets, with one 'E'nd-of-data
per file mentioned in the plot:

	plot "-" u 1:2, "" u 1:2
	   1 2
	   4 5
            E
	   1 3
	   4 6
	   E

> Now moving away from the simple case, I need to plot 48 channels of 
> floating point data from a 125Hz (as much as 4KHz) streaming source.

That's really not the kind of work gnuplot was ever meant for.  It's not
a real-time plotting engine, but an interactive program with a scripting
language.   It's not explicitly made slow, neither is there *any* kind
of real-time guarantee.

> I could store the data in a buffer and re-echo it to gnuplot 48 times
>  but I take a huge performance hit when I do.

No need to re-echo all of it --- just echoing the actual columns used
would be sufficient, i.e. two columns per '' in the command.