Re: [Gnuplot-info] Plotting partial file based on 3rd column

[Mikhail K. <mko...@gm...>]

Hi Thor

why not using 1/0 specification instead of '?':

echo "set table; plot 'data' u 1:((strcol(3) eq 'B')? \$2 : 1/0)" | gnuplot

# Curve 0 of 1, 5 points
# Curve title: "'data' u 1:((strcol(3) eq 'B')? $2 : 1/0)"
# x y type
  0  0  u
  0  0  u
  1  1  i
  2  4  i
  0  0  u

Mikhail

On 16/01/2013 10:53, Thor Andreassen wrote:
> Hi,
>
> I was under the impression that it is possible to plot only parts of a data
> file with the ternary operator (?:), strcol() and missing ('?'), but I get
> strange results.
>
> My data file contains:
>
> 8<------8<------8<------8<------
> cat<<  EOF>  data
> 1 2 A
> 2 3 A
> 1 1 B
> 2 4 B
> 3 2 A
> 4 3 A
> EOF
> 8<------8<------8<------8<------
>
> Now if try to plot the lines with 'B' in the third column:
>
> echo "set table; plot 'data' u 1:((strcol(3) eq 'B')? \$2 : '?')" | gnuplot
>
> The result is:
>
> 8<------8<------8<------8<------
> # Curve 0 of 1, 6 points
> # Curve title: "'data' u 1:((strcol(3) eq 'B')? $2 : '?')"
> # x y type
>   1  1.89869e-267  i
>   2  1.89869e-267  i
>   1  1  i
>   2  4  i
>   3  4  i
>   4  4  i
> 8<------8<------8<------8<------
>
> Which is not what I expected. Am I doing it wrong or is this a bug?
>
> The above was tested with a recent cvs version of Gnuplot.
>
> gnuplot>  show version long
>
>    G N U P L O T
>    Version 4.7 patchlevel 0    last modified 2013-01-08
>    Build System: Linux i686
>
>    Copyright (C) 1986-1993, 1998, 2004, 2007-2012
>    Thomas Williams, Colin Kelley and many others
>
>    gnuplot home:     http://www.gnuplot.info
>    mailing list:     gnu...@li...
>    faq, bugs, etc:   type "help FAQ"
>    immediate help:   type "help"  (plot window: hit 'h')
> Compile options:
> -READLINE  +LIBREADLINE  +HISTORY
> -BACKWARDS_COMPATIBILITY  +BINARY_DATA
> +GD_PNG  +GD_JPEG  +GD_TTF  +GD_GIF  +ANIMATION
> -USE_CWDRC  +X11  +X11_POLYGON  +MULTIBYTE  +X11_EXTERNAL +USE_MOUSE  +HIDDEN3D_QUADTREE
> +DATASTRINGS  +HISTOGRAMS  +OBJECTS  +STRINGVARS  +MACROS  +IMAGE  +USER_LINETYPES +STATS
>
> GNUPLOT_DRIVER_DIR = "/opt/stow/gnuplot/libexec/gnuplot/4.7"
> GNUPLOT_PS_DIR     = "/opt/stow/gnuplot/share/gnuplot/4.7/PostScript"
> HELPFILE           = "/opt/stow/gnuplot/share/gnuplot/4.7/gnuplot.gih"
>

-- 
Mikhail Kononets
Ph.D. Student
Marine Chemistry
Department of Chemistry and Molecular Biology
University of Gothenburg
Kemivagen 10
SE-412 96
Gothenburg, Sweden
office num.: +46-31-786-9063
mobile num.: +46-70-216-0936
e-mail: m.k...@ch...
         mko...@gm...