som_hits
Purpose
Calculate the response of the given data on the map.
Syntax
hits = som_hits(sMap, sData)
hits = som_hits(M, D)
hits = som_hits(..., mode)
Description
Returns a vector indicating the response of the map to the data.
The response of the data on the map can be calculated e.g. in
three ways, selected with the mode argument:
'crisp' traditional hit histogram: how many times each map unit
was the BMU for the data set
'kernel' a sum of neighborhood kernels, where a kernel
is positioned on the BMU of each data sample. The
neighborhood function is sMap.neigh and the
neighborhood width is sMap.trainhist(end).radius_fin
or 1 if this is not available
'fuzzy' fuzzy response calculated by summing
1

1 + (q/a)^2
for each data sample, where q is a vector containing
distance from the data sample to each map unit and
a is average quantization error
Required input arguments
sMap The vectors from among which the BMUs are searched
for. These must not have any unknown components (NaNs).
(struct) map struct
(matrix) codebook matrix, size munits x dim
sData The data vector(s) for which the BMUs are searched.
(struct) data struct
(matrix) data matrix, size dlen x dim
Optional input arguments
mode (string) The respond mode: 'crisp' (default), 'kernel'
or 'fuzzy'. 'kernel' can only be used if
the first argument (sMap) is a map struct.
Output arguments
hits (vector) The number of hits in each map unit.
Examples
hits = som_hits(sM,D);
hits = som_hits(sM,D,'kernel');
hits = som_hits(sM,D,'fuzzy');
See also
som_bmus
 Find BMUs and quantization errors for a given data set.
