Interpolate - Interpolate samples (positions, spikes, LFP, etc.) at given timestamps.
Interpolate samples (positions, spikes, LFP, etc.) at given timestamps. As a special
case, a point process can also be 'interpolated' by changing each original timestamp
t to the closest target timestamp t* such that t* <= t.
USAGE
[interpolated,discarded] = Interpolate(samples,timestamps,<options>)
samples list of <a href="matlab:help samples">samples</a> to interpolate
timestamps timestamps where the samples should be interpolated
<options> optional list of property-value pairs (see table below)
=========================================================================
Properties Values
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'type' 'linear' if samples are linear values (default), or
'circular' otherwise
'trim' discard ('on', default) or keep ('off') samples that would
require extrapolation. If kept, these samples are set to
NaN (this can be useful when the output is required to
have the same size as the input) (default = 'on')
'maxGap' time gaps between original and target times exceeding this
threshold will be ignored (default = Inf)
=========================================================================
OUTPUT
interpolated list of interpolated samples
discarded logical vector indicating for which timestamps the samples were
not interpolated (see option 'maxGap')
SEE
See also Diff.0001 function [interpolated,discarded] = Interpolate(samples,timestamps,varargin) 0002 0003 %Interpolate - Interpolate samples (positions, spikes, LFP, etc.) at given timestamps. 0004 % 0005 % Interpolate samples (positions, spikes, LFP, etc.) at given timestamps. As a special 0006 % case, a point process can also be 'interpolated' by changing each original timestamp 0007 % t to the closest target timestamp t* such that t* <= t. 0008 % 0009 % USAGE 0010 % 0011 % [interpolated,discarded] = Interpolate(samples,timestamps,<options>) 0012 % 0013 % samples list of <a href="matlab:help samples">samples</a> to interpolate 0014 % timestamps timestamps where the samples should be interpolated 0015 % <options> optional list of property-value pairs (see table below) 0016 % 0017 % ========================================================================= 0018 % Properties Values 0019 % ------------------------------------------------------------------------- 0020 % 'type' 'linear' if samples are linear values (default), or 0021 % 'circular' otherwise 0022 % 'trim' discard ('on', default) or keep ('off') samples that would 0023 % require extrapolation. If kept, these samples are set to 0024 % NaN (this can be useful when the output is required to 0025 % have the same size as the input) (default = 'on') 0026 % 'maxGap' time gaps between original and target times exceeding this 0027 % threshold will be ignored (default = Inf) 0028 % ========================================================================= 0029 % 0030 % OUTPUT 0031 % 0032 % interpolated list of interpolated samples 0033 % discarded logical vector indicating for which timestamps the samples were 0034 % not interpolated (see option 'maxGap') 0035 % 0036 % SEE 0037 % 0038 % See also Diff. 0039 0040 % Copyright (C) 2004-2011 by Michaël Zugaro 0041 % 0042 % This program is free software; you can redistribute it and/or modify 0043 % it under the terms of the GNU General Public License as published by 0044 % the Free Software Foundation; either version 3 of the License, or 0045 % (at your option) any later version. 0046 0047 % Default values 0048 trim = 'on'; 0049 maxGap = Inf; 0050 type = 'linear'; 0051 0052 if nargin < 2 | mod(length(varargin),2) ~= 0, 0053 error('Incorrect number of parameters (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).'); 0054 end 0055 if ~isdvector(timestamps), 0056 error('Incorrect timestamps - should be a vector (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).'); 0057 end 0058 timestamps = timestamps(:); 0059 0060 % Parse parameter list 0061 for j = 1:2:length(varargin), 0062 if ~ischar(varargin{j}), 0063 error(['Parameter ' num2str(j+2) ' is not a property (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).']); 0064 end 0065 switch(lower(varargin{j})), 0066 case 'type', 0067 type = varargin{j+1}; 0068 if ~isastring(type,'linear','circular'), 0069 error('Incorrect value for property ''type'' (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).'); 0070 end 0071 case 'trim', 0072 trim = lower(varargin{j+1}); 0073 if ~isastring(trim,'on','off'), 0074 error('Incorrect value for property ''trim'' (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).'); 0075 end 0076 case 'maxgap', 0077 maxGap = varargin{j+1}; 0078 if ~isdscalar(maxGap,'>=0'), 0079 error('Incorrect value for property ''maxGap'' (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).'); 0080 end 0081 otherwise, 0082 error(['Unknown property ''' num2str(varargin{j}) ''' (type ''help <a href="matlab:help Interpolate">Interpolate</a>'' for details).']); 0083 end 0084 end 0085 0086 interpolated = []; 0087 if isempty(timestamps) | isempty(samples), return; end 0088 0089 pointProcess = isvector(samples); 0090 0091 % Determine which target timestamps are too far away from sample timestamps (isolated) and should be discarded 0092 [~,isolated] = Match(timestamps,samples(:,1),'match','closest','error',maxGap); 0093 0094 if pointProcess, 0095 % 'Interpolate' samples at timestamps (see help above) 0096 [interpolated,~,discarded] = Match(samples,timestamps,'error',maxGap); 0097 else 0098 % Determine which timestamps would require extrapolation 0099 outside = logical(zeros(size(timestamps))); 0100 if strcmp(trim,'on'), 0101 outside = timestamps<samples(1,1)|timestamps>samples(end,1); 0102 end 0103 % Discard isolated timestamps and timestamps that would require extrapolation 0104 discarded = outside|isolated; 0105 timestamps(discarded) = []; 0106 % Circular data? 0107 if strcmp(type,'circular'), 0108 range = isradians(samples(:,2:end)); 0109 samples(:,2:end) = exp(i*samples(:,2:end)); 0110 end 0111 % Interpolate samples at timestamps 0112 interpolated = [timestamps interp1(samples(:,1),samples(:,2:end),timestamps)]; 0113 % Circular data? 0114 if strcmp(type,'circular'), 0115 interpolated(:,2:end) = wrap(angle(interpolated(:,2:end)),range); 0116 end 0117 end