function [data, peakresp] = normalize(data,trials,t,peakwin)
% this function normalizes data by first smoothing the psth of the
% trials indicated by the trials array (ONLY INCLUDE TRIALS THAT HAVE A
% PEAK RESPONSE, i.e. trials in which there was a stimulus). it looks for
% the peak in this smoothed psth within a given peak window, and divides
% all data by the size of this peak
% 
% input: 
% - data (time by trials, should be already BASELINE CORRECTED)
% - trials (array of booleans indicating which trials to include in the
% psth for peak calculation)
% - time axis in same unit as peak window
% - [start end] peak window
% 
% Rob Teeuwen 20190815

psth = nanmean(data(:,trials==1),2);
psths = smooth(psth,20,'lowess');
peakresp = max(psths(t>peakwin(1) & t<peakwin(2)));

data = data./peakresp;