[rrd-users] rrd graph - multiple graphs on one plot?

[Rob Conway]

Yes you can have multiple scales...however rrdtool cannot provide the scale.    If you normalise the data so it all fits on a single y axis, i.e. normalise everything to 0-100 %, all you then need to do is superimpose a scale onto the rrdtrend.  DO NOT LET rrd  print the scale just the trend area.   it is quite easy once you create a small picture (png) having the scale.

Imagemagick enables you to combine two .png files together and is a command line editor/tool for data manipulation under linux or I think windows.  I run it under a SLUG and linux ubuntu.  Thus you could make a complex multiscale axis and you just use imagemagick to combine the rrd graph and scale.  


The image below is just the rrdgraph combined with a scale to show alarm setpoint etc however theres nothing stopping you creating an alternative scale. 
http://img.photobucket.com/albums/v319/rjconway/rob.png

This is the scale file, image magic updates this with actual data then overlays the completed scale onto the trend...and in firefox it shows its transparency
http://img.photobucket.com/albums/v319/rjconway/tempscale.png

I use image magic to update the header on the web page below that shows real time data above the trend areas
http://smg.photobucket.com/albums/v319/rjconway/?action=view&current=newupdate.jpg

RRDTool and imagemagick and you have all the required tools to create a really nice html interface for you data


Imagemagic runs under linux and the NSLU2 slug ....

rob, Australia







  ----- Original Message ----- 
  From: Gregory Guthrie 
  To: rrd-users at lists.oetiker.ch 
  Sent: Thursday, October 04, 2007 6:08 AM
  Subject: [rrd-users] rrd graph - multiple graphs on one plot?


  I wanted to have multiple data on one graph, and also add an 
  additional set of y-axis labels.

  I'd like to have wind speed and direction on one graph, and have the 
  velocity labels as standard on the left Y-axis, but also add a 
  direction indicator (N S E W) scale label over the scaled 
  (0-360  =>  20-30) wind direction on the right hand side of the graph.

  A site with a similar thing is at: 
  http:/ / www.iwindsurf.com/windandwhere.iws?regionID=100&siteID=1399
  but they use icons for direction, I wanted to just plot it as a graph.

  Thanks,
  Greg


  -----------------------------------------------
  Gregory Guthrie

  MUM Faculty Mail - FM 1068
  Fairfield, IA 52557
  (641)472-7773
  ------------------------------------------------ 

  -------------------------------------------------------- 
  Dr. Gregory Guthrie 
           guthrie at mum.edu      (641)472-1125      Fax: -1103 
          Professor and Dean
          Computer Science Department 
          College of Computer Science and Mathematics
          Maharishi University of Management 
           http://www.mum.edu/cs_dept 
  --------------------------------------------------------




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