MAP

function [mappediih,centerfreqs] = map_iih_onto_log(iih,numchannels,sfreq)

%function to map an IPIH from the interval axis onto the frequency axis

%with no overlap and mean firing rate.

%

% Tim Juergens, September 2011

%

% input: iih: IPIH with dimensions interval (1) and time step (2)

%             the first dimension translates to time using the actual

%             sampling frequency

%        numchannels: number of desired channels

%        sfreq: sampling frequency

% output: mappediih: IPIH with dimensions frequency channel (1) and time

%                    step (2)

%         centerfreqs: center frequencies of the channels of mappediih

ctr_intervals = [1/sfreq:1/sfreq:size(iih,1)/sfreq];

lowestBF=1/ctr_intervals(end);

highestBF=10000;

borderfreqs = logspace(log10(lowestBF),log10(highestBF),numchannels+1);

for iCounter = 1:numchannels

    centerfreqs(iCounter)=(borderfreqs(iCounter)+borderfreqs(iCounter+1))/2;

end

for iCounter = 1:length(borderfreqs) %find the indices that correspond to the borderfrequencies of the BF filters

    [tmp,channelbordersIPIindex(iCounter)]=min(abs(borderfreqs(iCounter)-1./ctr_intervals));

end

for iCounter = 1:length(centerfreqs)

    %mapping with one interval sample overlap

    mappediih(iCounter,:) = mean(iih(channelbordersIPIindex(end-iCounter+1):channelbordersIPIindex(end-iCounter),:));

end

% OPTIONAL PLOTTING

            figure

            YTickIdx = 1:floor(numel(centerfreqs)/6):numel(centerfreqs);

            YTickIdxRev = numel(centerfreqs)+1-YTickIdx;

            if ~isempty(gca)

                axes(gca);  %#ok<MAXES>

                imagesc(mappediih);

                set(gca, 'YTick', YTickIdx);

                set(gca, 'YTickLabel', num2str(   centerfreqs(YTickIdxRev)', '%0.0f' ));

                ylabel('cf in Hz')

            end