Home > chronux > spectral_analysis > continuous > findpeaks.m

# findpeaks

## PURPOSE

Helper function to find peaks in a given continuous valued time series x

## SYNOPSIS

function xmax=findpeaks(data,threshold)

## DESCRIPTION

``` Helper function to find peaks in a given continuous valued time series x
Usage: xmax=findpeaks(data,threshold)
Input:
data     (data in time x channels/trials form or a single vector)
threshold (if specified returns locations of peaks at which data exceeds threshold) - optional
Output:
xmax     (locations of local maxima of data in a structure array of dimensions channels/trials)```

## CROSS-REFERENCE INFORMATION

This function calls:
This function is called by:
• fitlinesc fits significant sine waves to data (continuous data).

## SOURCE CODE

```0001 function xmax=findpeaks(data,threshold)
0002 % Helper function to find peaks in a given continuous valued time series x
0003 % Usage: xmax=findpeaks(data,threshold)
0004 % Input:
0005 %      data     (data in time x channels/trials form or a single vector)
0006 %      threshold (if specified returns locations of peaks at which data exceeds threshold) - optional
0007 % Output:
0008 %      xmax     (locations of local maxima of data in a structure array of dimensions channels/trials)
0009 if nargin < 1; error('Need data'); end;
0010 data=change_row_to_column(data);
0011 C=size(data,2);
0012 pp1=[data(1,:);data(1:end-1,:)];
0013 pp2=[data(2:end,:);data(end,:)];
0014 xmax(1:C)=struct('loc',[]);
0015 % for ch=1:C,
0016 %    if nargin ==1
0017 %      xmax(ch).loc=[xmax(ch).loc; find(data(:,ch)-pp1(:,ch)>0 & data(:,ch)-pp2(:,ch)>0)];
0018 %    else
0019 %      xmax(ch).loc=[xmax(ch).loc; find(data(:,ch)-pp1(:,ch)>0 & data(:,ch)-pp2(:,ch)>0 & data(:,ch)>threshold)];
0020 %    end
0021 % end
0022
0023 for ch=1:C,
0024    if nargin ==1
0025      xmax(ch).loc=[xmax(ch).loc; find(data(:,ch)-pp1(:,ch)>=0 & data(:,ch)-pp2(:,ch)>=0)];
0026    else
0027      xmax(ch).loc=[xmax(ch).loc; find(data(:,ch)-pp1(:,ch)>=0 & data(:,ch)-pp2(:,ch)>=0 & data(:,ch)>=threshold)];
0028    end
0029 end```

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