gnuplot-info

[Gnuplot-info] Short horizontal line become exaggerated in saved plots

[Rob S. <rob...@ut...>]

Hoping third times the charm, with this posting.  My first was rejected 
as not-a-member, the second seems to have simply wafted away...

I'm running gnuplot 4.2 patchlevel 6 on RHEL 6.6.

I draw a number of (usually quite short) lines 4pt thick throughout the 
plot. In the interactive window these are so short they are often barely 
visible (and that's a good thing). But they become exaggerated in the 
(viewing of) the saved plot, using jpeg, png or gif.

My line style for these is: set style line 4 linewidth 4 lc rgb "#8550FF"

each of them is plotted from a generated file of this form:

    1    23057190    2.709457    0.000000    23057190
    1    24552835    2.709457    0.000000    24552835

with this directive:

    plot ... redo/1801/wpw/runAvgRatio.0163257164" using 2:3 title ""
    axes x1y2 ls 4 with line [,another/file]*

and there are hundreds of them. the X values are base position on a 
chromosome scaled to full genome (0..3,000,000,000)

I view the saved images in either emacs (I know) or gimp or "eye of 
GNOME" and see the same bloat.

Does anyone have an explanation, or better yet a solution?

Happy to ship my plotable file, but keep in mind it references lots of 
the line files.

Re: [Gnuplot-info] Short horizontal line become exaggerated in saved plots

[Hans-Bernhard B. <HBB...@t-...>]

Am 14.04.2015 um 01:40 schrieb Rob Sargent:
> Hoping third times the charm, with this posting.  My first was rejected
> as not-a-member, the second seems to have simply wafted away...
>
> I'm running gnuplot 4.2 patchlevel 6 on RHEL 6.6.

Well, that version is old: 5.5 years.  So the first and foremost 
suggestion must be: update to something at least remotely current, like 
4.6 pl 6, or even 5.0

> I draw a number of (usually quite short) lines 4pt thick throughout the
> plot. In the interactive window these are so short they are often barely
> visible (and that's a good thing). But they become exaggerated in the
> (viewing of) the saved plot, using jpeg, png or gif.

Well, what do you expect a discrete, pixel-based terminal to do? You 
didn't even reveal how big you make those images...

> each of them is plotted from a generated file of this form:
>
>      1    23057190    2.709457    0.000000    23057190
>      1    24552835    2.709457    0.000000    24552835

That's a line covering just 1/2000th of your x axis range.  That leaves 
a normal-sized pixel image only one of two choices: display nothing at 
all, or display at least one pixel.  Neither of which you appear to 
want.  So what did you expect to happen?

Re: [Gnuplot-info] Short horizontal line become exaggerated in saved plots

[Rob S. <rob...@ut...>]

On 04/14/2015 02:44 PM, Hans-Bernhard Bröker wrote:
> Am 14.04.2015 um 01:40 schrieb Rob Sargent:
>> Hoping third times the charm, with this posting.  My first was rejected
>> as not-a-member, the second seems to have simply wafted away...
>>
>> I'm running gnuplot 4.2 patchlevel 6 on RHEL 6.6.
>
> Well, that version is old: 5.5 years.  So the first and foremost 
> suggestion must be: update to something at least remotely current, 
> like 4.6 pl 6, or even 5.0
>
 From where I sit, that's the release on RHEL. I do have rpm's for 4.6 
but I'm hesitant to rock the install boat for this utility. Call me 
chicken but several attempt to modernize RHEL 6 have been troublesome.
>> I draw a number of (usually quite short) lines 4pt thick throughout the
>> plot. In the interactive window these are so short they are often barely
>> visible (and that's a good thing). But they become exaggerated in the
>> (viewing of) the saved plot, using jpeg, png or gif.
>
> Well, what do you expect a discrete, pixel-based terminal to do? You 
> didn't even reveal how big you make those images...
I typically define the window as 1600x400 for the saved images. 
Interactively I do not specify a window geometry; simply stretch the 
window and play with regions using the right-click-drag.
>
>> each of them is plotted from a generated file of this form:
>>
>>      1    23057190    2.709457    0.000000    23057190
>>      1    24552835    2.709457    0.000000    24552835
>
> That's a line covering just 1/2000th of your x axis range.  That 
> leaves a normal-sized pixel image only one of two choices: display 
> nothing at all, or display at least one pixel.  Neither of which you 
> appear to want.  So what did you expect to happen?
Perhaps I expect too much.  The interactive viewer (x11) does a 
perfectly acceptable single pixel rendering.  I'm confused why in the 
saved images, in multiple formats, viewed by a variety of tools, these 
barely noticeable lines are puffed up. Oh and whether or not I can do 
anything about it - if it's a problem in the save-to-file action of 
gnuplot I will upgrade to 4.6 (maybe 5) if this is a known, and fixed, 
issue.

Thanks,
rjs