matlab - Count identical elements near each other in matrix -


consider matrix like

a =  0     1     0     1                1     1     0     0                0     0     0     0                1     1     1     1

i calculate average size of each cluster of 1's. define cluster occurring when 2 or more 1's near each other, i.e. next or above/below. eg, in matrix there cluster of size 3 in top left hand corner , cluster of size 4 in bottom row.

i need way extract information in non-visual way because need many times different a.

you may want use bwlabel isolates connected components (clusters of 1) in binary matrix. 

a =  [0     1     0     1                 1     1     0     0                 0     0     0     0                 1     1     1     1 ];  [l,n] = bwlabel(a,8)  % # 8-pixel stencil                      % # (i.e. hor/vert/diag first neighbors)

or 

[l,n] = bwlabel(a,4)  % # 4-pixel stencil                        % # (just horizontal & vertical neighbors)    l =  0     1     0     3       1     1     0     0       0     0     0     0       2     2     2     2

doing so, obtain matrix l labels n different connected components.

then may want extract statistics; instance may want histogram size of clusters.

   cluster_size =  hist(l(:),0:n);    cluster_size = cluster_size(2:end);  % # histogram of component vs. size                                          % # (without zeros)         hist(cluster_size)                   % # histogram of sizes

enter image description here

which tells thay have 1 cluser of 1 element, 1 cluster of 3 , 1 cluster of four.

finally, if looking average size of clusters, can do

mean(cluster_size)       2.6667

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