rdp/ruby_gnuplot

Plotting timeseries data

Opened this issue · 7 comments

wvengen commented

How can timeseries data best be plotted using this gem?

When using

require 'gnuplot'

Gnuplot.open do |gp|
  Gnuplot::Plot.new(gp) do |plot|
    plot.xdata :time
    plot.timefmt '"%s"'
    plot.format 'x "%H:%m"'

    plot.data << Gnuplot::DataSet.new( [[Time.now, Time.now + 60], [1, 2]] ) do |ds|
      ds.with = "linespoints"
      ds.title = "Howdy"
    end
  end
end

the errors I get are:

gnuplot> plot '-' title 'Howdy' with linespoints
                                                ^
         line 0: Need full using spec for x time data


gnuplot> 2015-11-23 18:46:14 +0100 1
         ^
         line 0: invalid command


gnuplot> 2015-11-23 18:47:14 +0100 2
         ^
         line 0: invalid command

Workaround: add ds.using = '1:2' to the dataset.
Would it be better if this gem includes a default using for each dataset?

See also http://stackoverflow.com/a/18121824/2866660

rdp commented

there is a ds.using = is that what you're referring to? I think maybe you found the answer to your own question :)

wvengen commented

Yes, using ds.using makes it work. But wouldn't it be better if ruby-gnuplot would include this by default?

rdp commented

Hmm...I don't understand the internal workings enough of gnuplot to
understand this enough to know exactly what to do here. However, I will
definitely leave this thread up so that followers can use your tips to
figure it out, thank you!

On Thu, Nov 26, 2015 at 2:50 AM, wvengen notifications@github.com wrote:

Yes, using ds.using makes it work. But wouldn't it be better if
ruby-gnuplot would include this by default?

—
Reply to this email directly or view it on GitHub
#41 (comment).

sixtyfive commented

Now, 5 years later, that same code only results in this for me:

Warning: empty x range [2020:2020], adjusting to [1999.8:2040.2]
Warning: empty y range [0:0], adjusting to [-1:1]

Could that be due to the newer Gnuplot (5.2)?

rdp commented
sixtyfive commented

No, gnuplot supports timeseries data just fine. And as I understand the initial description of this Issue here, it also used to work with ruby_gnuplot, if only you didn't forget an appropriate ds.using. That doesn't seem to be the case anymore though.

rdp commented