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Archive for July, 2009

Proportion Nomogram

Are you intrigued by nomograms but have no idea how to go about drawing them? PyNomo is an amazing, free software package for drawing precision nomograms. The output is in vector form in a PDF or EPS file, so it can be printed in any size and still retain its sharpness. PyNomo directly supports 9 basic types of nomograms based simply on the format of the equation, so for these types there is no need to convert the equation to the standard nomographic determinant or use geometric relations. But it also supports compound nomograms as well as more complicated equations that have been cast into general determinant form, so it can produce output for any equation that can be plotted as a nomogram.

When I started writing an essay on using PyNomo my plans were to show three examples of nomograms. But I had so much fun making really cool nomograms that the essay turned out to be more of a user’s manual, with examples of all the supported types and descriptions of the many parameters you can use to customize your nomograms. Leif Roschier, the author of the software, spent a great deal of time reviewing draft versions of the essay and making software updates for new features that were rolled into it, so the essay is comprehensive in scope and quite complete in details and practical advice. PyNomo is clearly my choice for drawing nomograms going forward, and I think you will find it as uniquely wonderful as I have.

The essay is too long and the example nomograms too detailed to be rendered in HTML here. The PDF version of the essay (Version 1.1) can be found here. The PyNomo website, which also contains many examples, is found here.

[NEW - December 21, 2011]:  Detailed instructions on downloading and installing all required software applications onto a Windows XP or Windows 7 PC can be found here.

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Updated October 19, 2009, to Version 1.1 for the new features of PyNomo Release 0.2.2:

  1.  Automatic spacing of tick marks along scales—more tick marks where space is available and less where it’s crowded.
  2. Drawing of sample isopleths  between specified values on scales.
  3. Printing of only significant digits of scale values by default, producing a cleaner-looking nomogram overall.

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