gnuplot-beta

histograms?

[Daniel J S. <dan...@ie...>]

I assume that the following is still a correct statement with the latest version of gnuplot:

 `histeps` is only a plotting style; `gnuplot` does not have the ability to
 create bins and determine their population from some data set.

Dan

Re: histograms?

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

Daniel J Sebald wrote:
> I assume that the following is still a correct statement with the latest 
> version of gnuplot:
> 
> `histeps` is only a plotting style; `gnuplot` does not have the ability to
> create bins and determine their population from some data set.

Not strictly.  Since version 4.0 at least, there's a rudimentary 
histogram collection tool available: the 'smooth frequency' filter:

	binwidth = 5
	bin(x) = binwidth * floor(x / binwidth)
	plot 'data' using (bin($1)):1 w histeps

To my shame I haven't experimented with Ethan's histogram plotting 
machine enough to know how much better it might be at this same task.

Re: histograms?

[Daniel J S. <dan...@ie...>]

Hans-Bernhard Br=F6ker wrote:
> Daniel J Sebald wrote:
>=20
>> I assume that the following is still a correct statement with the=20
>> latest version of gnuplot:
>>
>> `histeps` is only a plotting style; `gnuplot` does not have the=20
>> ability to
>> create bins and determine their population from some data set.
>=20
>=20
> Not strictly.  Since version 4.0 at least, there's a rudimentary=20
> histogram collection tool available: the 'smooth frequency' filter:
>=20
>     binwidth =3D 5
>     bin(x) =3D binwidth * floor(x / binwidth)
>     plot 'data' using (bin($1)):1 w histeps
>=20
> To my shame I haven't experimented with Ethan's histogram plotting=20
> machine enough to know how much better it might be at this same task.

That is why I asked the question.  I've seen Ethan's histogram demos, loo=
ked at the script, but total understand if it does the binning and now th=
at 'histeps' comment is obsolete.

Anyway, if that prob3.dem I gave can be used, I'd think that doing a hist=
ogram of randomly generated data would be a worthwhile addition.

Dan

Re: histograms?

[Ethan M. <merritt@u.washington.edu>]

On Wednesday 10 May 2006 10:01 am, Daniel J Sebald wrote:
> Hans-Bernhard Br=F6ker wrote:
> > I haven't experimented with Ethan's histogram plotting=20
> > machine enough to know how much better it might be at this same task.

The "with histograms" style only assists in plot layout.
It does not do any statistical analysis on its own.
I use external scripting to prepare the data for plotting.
=20
> That is why I asked the question. =20
> I've seen Ethan's histogram demos, looked at the script, but=20
> total understand if it does the binning and now that 'histeps'=20
> comment is obsolete.  =20

I have not myself ever found a use for 'histeps'.
But different people plot different things, so I cannot
conclude that it is obsolete.

The 'histograms' plot mode basically automates what would
otherwise be a very cumbersome set of commands using either
'impulses' or 'boxes'.

You can use 'impulses' to created row-stacked histogram plots
by setting the linewidth appropriately and explicitly giving
appropriate summations in the plot command.

E.g.
    set style histogram rowstacked
    plot 'foo' u 1, '' u 2, '' u 3

is more or less equivalent to
    set style impulses
    plot 'foo' u ($1+$2+$3), '' u ($1+$2), '' u ($3)

Similarly you can use 'boxes' to generate clustered histogram
plots by explicitly giving x-axis offsets to the contributing
data sets.

E.g.
    set style histogram cluster
    plot 'foo' u 1, '' u 2, '' u 3

is more or less equivalent to
    set style boxes
    set boxwidth 0.1 abs
    plot 'foo' u ($0-.2):1, '' u ($0):2, '' u ($0+.2):3

In either case the histograms style also allows additional
features such as automatic construction of appropriate
key entries, placement of axis labels, and multiple=20
histograms on the same set of axes.


=2D-=20
Ethan A Merritt
Biomolecular Structure Center
University of Washington, Seattle WA