gnuplot-info

[Gnuplot-info] point type depending on data column

[seb_kramm <seb...@ya...>]

Hello,

When plotting points from a datafile, gnuplot offers me the ability to change the 
color of the point depending of some column:
plot "datafile" using 1:2:3 with points palette

I can also have the size of the point depend on a column of data:
plot "datafile" using 1:2:3 with points ps variable

Now, I want to have the type of the point depend on a column of data. Assuming of 
course that this column has values lying in the range
[0-nb of point types that the terminal has]

How can I do this ? This:
plot "datafile" using 1:2:3 with points pt variable
does not work, neither does this:
plot "datafile" using 1:2 with points pt $3

Any idea ?

Re: [Gnuplot-info] point type depending on data column

[Ethan A M. <eam...@gm...>]

On Friday, 31 May 2013, seb_kramm wrote:
> Hello,
> 
> When plotting points from a datafile, gnuplot offers me the ability to change the 
> color of the point depending of some column:
> plot "datafile" using 1:2:3 with points palette
> 
> I can also have the size of the point depend on a column of data:
> plot "datafile" using 1:2:3 with points ps variable
> 
> Now, I want to have the type of the point depend on a column of data.

The closest is to use selected single character glyphs instead of
the predefined point types.  Then you can use a command such as

    set encoding utf8
    symbol = "+⁕∙∎⊙⊡★☆♠♣♥♦"
    plot FOO using 1:2:(symbol[int($3):int($3)]) with labels

A more complicated variant using sprintf allows you to also vary
the color and size of the font used.   See for example
    http://gnuplot.sourceforge.net/demo_cvs/cities.html

Re: [Gnuplot-info] point type depending on data column

[seb_kramm <seb...@ya...>]

On 05/31/2013 05:13 PM, Ethan A Merritt wrote:
> On Friday, 31 May 2013, seb_kramm wrote:
>> Now, I want to have the type of the point depend on a column of data.
>
> The closest is to use selected single character glyphs instead of
> the predefined point types.  Then you can use a command such as
>
>      set encoding utf8
>      symbol = "+⁕∙∎⊙⊡★☆♠♣♥♦"
>      plot FOO using 1:2:(symbol[int($3):int($3)]) with labels
>
> A more complicated variant using sprintf allows you to also vary
> the color and size of the font used.   See for example
>      http://gnuplot.sourceforge.net/demo_cvs/cities.html

Thanks Ethan, very interesting as usual. However, even if it does work, I don't 
understand how: where does this data specifier come from:
symbol[int($3):int($3)]
I've been searching the pdf doc (4.6) for the string "symbol", found nothing 
relevant, so I'm puzzled...
An undocumented feature ?

Thanks
Sebastien Kramm

Re: [Gnuplot-info] point type depending on data column

[Thomas S. <t.s...@fz...>]

seb_kramm <seb_kramm <at> yahoo.fr> writes:

> On 05/31/2013 05:13 PM, Ethan A Merritt wrote:
> > ...
> >      set encoding utf8
> >      symbol = "+⁕∙∎⊙⊡★☆♠♣♥♦"
> >      plot FOO using 1:2:(symbol[int($3):int($3)]) with labels
> > ...
> 
> Thanks Ethan, very interesting as usual. However, even if it
> does work, I don't understand how:
> where does this data specifier come from:
> symbol[int($3):int($3)]

it's a substring of the string contained
in the variable 'symbol'.

see 'help string'