[R-sig-Geo] Student request for help in Self Organizing Map (SOM)

[Riaz Bibi]

Dear

I am Bibi, a PhD student of Environmental Science in South Korea.  I am
currently writing my research paper and to deal with data I need to do Self
Organizing Map (SOM).

I am using R version 4.1.0 (2021-05-18) with kohonen package version
‘3.0.10’.

I was following this tutorial given
http://rstudio-pubs-static.s3.amazonaws.com/437468_136a369149e24f24a4d0c152860ab4c3.html
.

But I have a small issue . To check the efficiency of SOM model, I need to
find out topographic error, which I could not figure out.

I will be really thankful if you please tell me how I can calculate
topographic error or any alternative term or which is used the topographic
error or what is topographic error as for example the quantization error is
"Mean distance to the closest unit in the map".

Is there anything like this for topographic error too?

Please accept my apology if I wrote or mentioned something inappropriate.

Looking forward to hearing back.

Kind regards

Bibi

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