gnuplot on ruby

[soxinbox]

I installed gnuplot gem, and I am getting some syntax errors when I try to
run the samples on the projects web page.

>ruby test.rb
c:/programs/ruby/lib/ruby/gems/1.8/gems/gnuplot-2.1/lib/gnuplot.rb:20:in
`popen': No such file or directory - which gnuplot (Errno::ENOENT)
from
c:/programs/ruby/lib/ruby/gems/1.8/gems/gnuplot-2.1/lib/gnuplot.rb:20:in
`open'
from test.rb:2
>Exit code: 1

my test code is copied directly from the gnuplot ruby project web page
except the added require 'gnuplot' which is not mentioned in the example. I
think I am missing something simple here.

require 'gnuplot'
Gnuplot.open do |gp|
Gnuplot::Plot.new( gp ) do |plot|

plot.title "Array Plot Example"
plot.ylabel "x"
plot.xlabel "x^2"

x = (0..50).collect { |v| v.to_f }
y = x.collect { |v| v ** 2 }

plot.data << Gnuplot::DataSet.new( [x, y] ) do |ds|
ds.with = "linespoints"
ds.notitle
end
end
end

any help is appreciated.

[Ara.T.Howard]

On Fri, 21 Oct 2005, soxinbox wrote:

> I installed gnuplot gem, and I am getting some syntax errors when I try to
> run the samples on the projects web page.
>
>> ruby test.rb
> c:/programs/ruby/lib/ruby/gems/1.8/gems/gnuplot-2.1/lib/gnuplot.rb:20:in
> `popen': No such file or directory - which gnuplot (Errno::ENOENT)
> from

it looks like the code must do

IO::popen `which gnuplot`

so either

- gnuplot is not on your system

- gnuplot is not in your path

can you verify both of these? from the shell do

~:> which -a gnuplot

-a
--
===============================================================================
| email :: ara [dot] t [dot] howard [at] noaa [dot] gov
| phone :: 303.497.6469
| anything that contradicts experience and logic should be abandoned.
| -- h.h. the 14th dalai lama
===============================================================================

[gordon....@gmail.com]

Ara.T.Howard wrote:
> On Fri, 21 Oct 2005, soxinbox wrote:
>
> > I installed gnuplot gem, and I am getting some syntax errors when I try to
> > run the samples on the projects web page.
> >
> >> ruby test.rb
> > c:/programs/ruby/lib/ruby/gems/1.8/gems/gnuplot-2.1/lib/gnuplot.rb:20:in
> > `popen': No such file or directory - which gnuplot (Errno::ENOENT)
> > from
>
> it looks like the code must do
>
> IO::popen `which gnuplot`
>
> so either
>
> - gnuplot is not on your system
>
> - gnuplot is not in your path
>
> can you verify both of these? from the shell do
>
> ~:> which -a gnuplot
>

Ara is completely correct with his diagnosis. You have two choices,
either ensure that gnuplot is in your path or hardcode the path in the
gnuplot.rb file. I've struggled for a number of years on how to
improvie this but haven't been able to come up with something better
that satisfies my sense of right and wrong. Suggestions would be
appreciated.

Gordon

[soxinbox]

<gordon....@gmail.com> wrote in message
news:1129898636.0...@z14g2000cwz.googlegroups.com...

Aha! I see it now. The problem isn't that gnuplot isn't in the path, but
that 'which' is not a standard command on windows XP.
I guess not many people have tried running this under windows.

[soxinbox]

gordon, It looks like the gnuplot executable on windows needs to be
pgnuplot.exe. Might I suggest that when on windows you set cmd = "pgnuplot"
and assume it is in the path. I don't know the ruby way to check for
platform, perhaps ENV["OS"].downcase.include?("win") or some such hack.

<gordon....@gmail.com> wrote in message
news:1129898636.0...@z14g2000cwz.googlegroups.com...

[Ara.T.Howard]

maybe somthing like (un-tested):

def which bin
path = ENV['PATH'] # || ENV['WHAT_EVER_WINDOWS_PATH_VAR_IS']
path.split(File::PATH_SEPARATOR).each do |dir|
candidate = File::join dir, bin
return candidate if File::executable? candidate
end
return nil
end

gnuplot = ENV['RB_GNUPLOT'] || 'gnuplot'

gnuplot = which gnuplot or raise 'gnuplot is not in your path'

or, if windows isn't a concern

gnuplot = `which gnuplot`

raise 'gnuplot not in your path' unless $? == 0

IO::popen gnuplot

thanks for the good work on gnuplot btw - i've used in many times.

cheers.

[soxinbox]

You will have to add something to change the search to look for pgnuplot.exe
as there is no gnuplot.exe on windows. I have just started using this, but I
agree it looks cool. I hope to use it to output some technical graphs.
Thanks to those that created gnuplot and the ruby adaptation layer.

"Ara.T.Howard" <Ara.T....@noaa.gov> wrote in message
news:Pine.LNX.4.62.05...@harp.ngdc.noaa.gov...

[Edwin]

While we are on the topic off rgnuplot, does anybody know if it is
possible to still "turn" 3d graphs when called from ruby. If I make a
graph directly in gnuplot I can spin it around with the mouse to look at
it from different sides. With rgnuplot that doesn't seem possible.

(This is on linux)

Edwin

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[Patrick Hurley]

Another FYI, I have found that under windows, the gnuplot from cygwin
is actually better than the native pgnuplot, for handling piped input
(and cygwin will also fix the missing which issue).

pth

[gordon....@gmail.com]

I'm not too familiar with the interactive gnuplot capabilities (I
stepped out of gnuplot development around this time and don't really
care about the interactive part). When the plot window is up it is
being executed from within gnuplot so it should respond the exact same
as it would interactively.

[gordon....@gmail.com]

Sorry for the delay in replying, I only participate in the digest mode.

I'll put something like Ara mentioned into the codebase and put a new
release out within the next week. Thanks for the good suggestions.

Gordon

[steve...@gmail.com]

Hi Edwin,

can you please tell me how to generate 3d graphs using rgnuplot?

I'm trying this for a few days.

Thanks, steve