From: Daniel N <has.sox@...>
Date: 2006-08-04T08:19:48+09:00
Subject: Re: How to tell when IO::popen is finished?

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On 8/4/06, ara.t.howard@noaa.gov <ara.t.howard@noaa.gov> wrote:
>
> On Thu, 3 Aug 2006, Daniel N wrote:
>
> >> I'm using Gnuplot the open method is
>
> <snip>
>
> this works fine on my box:
>
>      harp:~ > cat a.rb
>      require 'rubygems'
>      require 'gnuplot'
>
>      PNG = ARGV.shift || 'test.png'
>
>      def Gnuplot.open( persist=true )
>        cmd = Gnuplot.gnuplot( persist ) or raise 'gnuplot not found'
>        IO::popen( cmd, "w") { |io| yield io }
>      end
>
>
>      def make_chart( )
>      Gnuplot.open() do |gp|
>        Gnuplot::Plot.new(gp) do |plot|
>          plot.terminal  "png"
>          plot.output  PNG
>
>          plot.title  "Array Plot Example"
>          plot.ylabel "x"
>          plot.xlabel "x^2"
>
>          x = (0..200).collect { |v| v.to_f }
>          y = x.collect { |v| v ** 2 }
>
>          plot.data << Gnuplot::DataSet.new( [x, y] ) do |ds|
>            ds.with = "lines"
>            ds.notitle
>            ds.linewidth = 6
>
>          end
>        end
>
>      end
>      end
>
>      make_chart
>
>      p File.stat(PNG)
>
>      # works if you have image magick installed
>      system "display #{ PNG }"
>
>
>      harp:~ > ruby a.rb
>      #<File::Stat dev=0x306, ino=33786, mode=0100664, nlink=1, uid=447,
> gid=447, rdev=0x51e1, size=3583, blksize=4096, blocks=8, atime=Thu Aug 03
> 08:53:07 MDT 2006, mtime=Thu Aug 03 08:53:50 MDT 2006, ctime=Thu Aug 03
> 08:53:50 MDT 2006>
>
>
> i think your issue was '/test2.png' - unless you're root i doubt you can
> open
> that file.
>
> regards.
>
> -a
> --
> we can never obtain peace in the outer world until we make peace with
> ourselves.
> - h.h. the 14th dali lama
>
>
I'm on windows :)  I don't need root.  Ohhh gives me goosebumps ;)

The problem isn't that the file isn't created.  It's just that I don't know
when it's finished being written.

I want to incorporate this into an app but I don't want to go trying to grab
the image if it doenst exist yet.

I'm not quite sure how your using PNG in your code above.  Is this a
constant of gnuplot?

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