Matlab Code for Spike Interval Distances Between Spike Trains
main cost-based metrics page
algorithm page for cost-based metrics
Matlab code for Spike Interval Metric
<![CDATA[
function [d,scr]=spkd_int_post(tli,tlj,cost,tsamp)
%
% d=spkd(tli,tlj,cost) calculates the "spike interval" distance
% (Victor & Purpura 1996) for a single cost
%
% input variables
% tli: vector spike times for first spike train
% tlj: vector spike times for second spike train
% cost: cost per unit time to move a spike
% tsamp: the length of the entire interval
% calculates distance between two spike trains in the spike interval metric
% by a continuum modification of the sellers algorithm
% end conditions: the first and last ISI are expanded as needed to minimize
% the total cost
% Original Copyright (c) 1999 by Daniel Reich and Jonathan Victor.
% Translated to Matlab by Christina Behrend from FORTRAN code by Jonathan Victor.
nspi=length(tli); % number of spike times in train 1
nspj=length(tlj); % number of spike times in train 2
ni = nspi+1; % number of intervals in train 1
nj = nspj+1; % number of intervals in train 2
scr=zeros(ni+1,nj+1);
% define calculation for a cost of zero
if cost==0
d=abs(nspi-nspj);
return
end
% INITIALIZE MARGINS WITH COST OF ADDING A SPIKE
scr(:,1)=(0:ni)';
scr(1,:)=(0:nj);
for i = 1:ni
if (i == 1) && (i == ni)
di = tsamp;
elseif (i == 1) && (i < ni)
di = tli(i);
elseif (i > 1) && (i == ni)
di = tsamp-tli(i-1);
elseif (i > 1) && (i < ni)
di = tli(i)-tli(i-1);
end
iend = 0;
if ((i == 1) || (i == ni))
iend = 1;
end
for j = 1:nj
if (j == 1) && (j == nj)
dj = tsamp;
elseif (j == 1) && (j < nj)
dj = tlj(j);
elseif (j > 1) && (j == nj)
dj = tsamp-tlj(j-1);
elseif (j > 1) && (j < nj)
dj = tlj(j)-tlj(j-1);
end
dist = abs(di-dj);
jend = 0;
if ((j == 1) || (j == nj))
jend = 1;
end
if (iend == 1) && (jend == 1)
dist = 0;
elseif (iend == 1)
dist = max(0,di-dj);
elseif (jend == 1)
dist = max(0,dj-di);
end
scr(i+1,j+1)=min([scr(i,j+1)+1 scr(i+1,j)+1 scr(i,j)+cost*dist]);
end
end
d = scr(ni+1,nj+1);
]]>