Tuesday 18 June 2013

How to introduce your own normalization scheme for spiderplots?

Many users would like to add a new normalization scheme to their  spiderplots in GCDkit, or at least to alter some normalization value or change the order of elements. It is easier than you may think.

The composition of various standards available for normalization and subsequent plotting of spiderplots is stored in the file 'spider.data' in the main GCDkit directory. It is a comma delimited and may look  like this:
REE chondrite (Boynton 1984)

ORG (PearceEtAl.1984)

For each normalization scheme, there are always three rows, separated by an empty one from the previous record.

1. The first row contains the title and reference. If the title starts with 'REE', the normalization is supposed to be for REE only and special parameters, such as 'Eu/Eu*', are calculated.

2. The second line gives a comma delimited list of elements in the order they should appear on the plot.

3. The last line is a comma delimited list of normalization values. Please note that the trailing zero before decimal point is optional.

As the file 'spider.data' is read every time spiderplot is drawn, the user can add or delete normalization schemes on his will using any text editor, such as Notepad. Just make sure that you keep a backup of copy of the original file somewhere safe, in case that something gets wrong.

Happy plotting!


  1. hello, sorry it dosn't work??? the spider file acceptes no changes!!! what to do please? I want to added to values of REE C1-Chondrite of McDonough & Sun for the normalisation.

    1. Hi,
      did you checked your writing permissions for the GCDkit folder? It seems to me that Win system is blocking the file change, rather than the GCDkit itself. Could you provide more detail?

    2. This comment has been removed by the author.

  2. Hello. The data file could not be edited. While I am trying to save the file a message is popping up "You do not have permission to open this file. See the owner of the file or an administrator to obtain permission." How should I do this?

  3. Thank you very much, it was very helpful to me