survey performed by Juha Ikonen, May 21st 1999

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Program name Nenet 1.0b
Availability Available freely from the website
Purpose Educational
Operating system Windows 95, Windows NT 3.5x and Windows NT 4.0
User interface Windows 95 - style graphical user interface. [speed of usage,user friendliness]
Documentation Good online help which also reveals some theory of the SOM algorithm

[General comments]

SOM features

map parameters
Teaching algorithm Standard, map is updated after presenting each vector of the training data set. Implementation appears to be correct.
Map size Minimum 2 x 2 cells, maximum 100 x 100 cells
Map lattice and shape Map lattice is rectangular or hexagonal, map shape is always rectangular.
Neighborhood function Function type: Bubble or gaussian
Neighborhood size (h): Both initial and final values can be set by user.
[type (linear, 1/t, other), parameters]
Learning rate (alpha): Linear or inverse time (1/t).
[type (linear, 1/t, other), parameters]
Initialization Linear or random.
Distance function Euclidian
Unknown components Not allowed
Teaching length Explicit, measured in steps. Ending conditions can not be used.
[Windows NT 4.0, 200 MHz Pentium MMX, 128 MB RAM]
16 seconds for standard run.
Results Normal [quantization error, topographic error]

[Comments on SOM implementation]


Input formats ASCII for both of the data and map files
Data handling and selection Scaling by Range: the values are scaled between [0,1] for each component separately.
Scaling by Variance: the variance of the components is scaled to 1 and the mean to 0 for each parameter level.
No data selecting functions, the program processes the entire data set. [flexibility,usability]
Output formats ASCII
Map measures Not implemented.
Labeling Simple, neurons and vector components can be labelled.
Clustering By visualization.
Inspection of neurons Simple, vector values can be viewed by selecting desired neurons.
Clusters/map shape Standard and interpolated Umatrix, 2D and 3D histograms.
Correlations Not implemented.
Data projections A group of data vectors can be projected on a map (histogram presentation).
Markers Labels only.
Monday, 09-Oct-2000 12:53:09 EEST