368 lines
18 KiB
Matlab
368 lines
18 KiB
Matlab
function DataTable = nappBackground(DataTable,varargin)
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%NAPPBACKGROUND Removes background from photoelectron or XAS spectra.
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% This function determines and removes the background from PE or XAS
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% spectra using mean subtraction or curve fitting (linear or exponential).
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% Background correction can be performed on kinetic energy, binding energy,
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% or X-ray photon energy scales. Results are optionally normalized by
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% dividing instead of subtracting.
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%
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% SYNTAX
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% ------
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% DataTable = NAPPBACKGROUND(DataTable, energyStart, energyEnd)
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%
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% DataTable = NAPPBACKGROUND(DataTable, energyStart, energyEnd, 'Name', Value)
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%
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% EXAMPLES
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% --------
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% % Simple mean subtraction with kinetic energy scale
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% DataTable = nappBackground(DataTable, 368, 370);
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%
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% % Linear fit on selected rows with binding energy scale
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% DataTable = nappBackground(DataTable, 368, 370, ...
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% 'tableSelection', tmpDataSelection, ...
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% 'energyScale', 'binding', ...
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% 'mode', 'linfit', ...
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% 'showFigures', 'off');
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%
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% INPUT ARGUMENTS
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% ---------------
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% DataTable table
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% Data table containing spectra and energy scales. Must contain
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% one of the following variables: 'spectrum_counts',
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% 'spectrum_countsPerSecond', or 'spectrum_countsNorm'.
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%
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% energyStart — Start energies for excluded ranges
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% Numeric scalar or vector.
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% Defines the lower bound(s) of the data range(s) excluded from
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% background fitting.
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%
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% energyEnd — End energies for excluded ranges
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% Numeric scalar or vector.
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% Defines the upper bound(s) of the data range(s) excluded from
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% background fitting.
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%
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% If energyStart and energyEnd are scalars, the range between
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% energyStart and energyEnd is excluded from the fit (for example,
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% to exclude the main peak).
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%
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% If energyStart is a two-element vector, the range from the first
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% data point to the second value of energyStart is additionally
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% excluded.
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% If energyEnd is a two-element vector, the range from the second
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% value of energyEnd to the end of the dataset is additionally
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% excluded.
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%
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% Specify vector values as comma-separated entries in brackets,
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% for example [395, 407].
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%
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%
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% NAME-VALUE PAIR ARGUMENTS (optional)
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% ------------------------------------
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% 'tableSelection' logical array (default: all rows)
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% Logical index to filter rows in DataTable.
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% Example: tableSelection = DataTable.quality > 0.8
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%
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% 'tableVariable' char vector (default: 'spectrum_countsPerSecond')
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% Spectral variable to process. Must be one of:
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% - 'spectrum_counts'
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% - 'spectrum_countsPerSecond'
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% - 'spectrum_countsNorm'
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%
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% 'mode' char vector (default: 'mean')
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% Background subtraction method:
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% - 'mean': subtract mean intensity in energy range
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% - 'linfit': subtract linear regression (poly1 fit)
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% - 'exponential': subtract exponential fit (exp2)
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% - 'mean, divide': divide by mean (normalization)
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% - 'linfit, divide': divide by linear fit
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% - 'exponential, divide': divide by exponential fit
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%
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% 'energyScale' char vector (default: 'kinetic')
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% Energy axis to use for background calculation:
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% - 'kinetic': uses scientaEkin_eV column
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% - 'binding': uses bindingEnergy_eV column
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% - 'xRay': uses xRayEkin_eV column (for NEXAFS data)
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%
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% 'showFigures' char vector (default: 'on')
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% Display fit visualization:
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% - 'on': show fit plot with data and excluded points
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% - 'off': suppress figure output
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%
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% OUTPUT ARGUMENTS
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% ----------------
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% DataTable table
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% Updated data table with background-corrected spectra. The table
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% variable specified by 'tableVariable' is overwritten with
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% corrected data. If mode contains 'divide', results are written
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% to 'spectrum_countsNorm' instead.
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%
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% Three log columns are added/updated:
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% - logBackgroundMode: fitting method used
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% - logBackgroundRange: [energyStart, energyEnd] for each row
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% - logBackgroundDate: timestamp of processing
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%
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% NOTES
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% -----
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% - Empty or missing spectra in tableVariable will trigger an error.
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%
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% SEE ALSO
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% --------
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% inputParser, fit, fittype, prepareCurveData, excludedata
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% Define conditions and defaults of input
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defaultTableVariable = 'spectrum_countsPerSecond';
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expectedTableVariable = {'spectrum_counts','spectrum_countsPerSecond','spectrum_countsNorm'};
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defaultMode = 'mean';
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expectedMode = {'mean','linfit','exponential','mean, divide','linfit, divide','exponential, divide'};
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defaultTableSelection = true(size(DataTable,1),1);
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defaultShowFigures = 'on';
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expectedShowFigures = {'on','off'};
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defaultEnergyScale = 'kinetic';
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expectedEnergyScale = {'kinetic','binding','xRay'};
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% Parse input
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p = inputParser;
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addRequired(p,'DataTable',@istable);
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addRequired(p,'energyStart',@isnumeric)
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addRequired(p,'energyEnd',@isnumeric)
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addOptional(p,'tableSelection',defaultTableSelection,@islogical);
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addParameter(p,'tableVariable',defaultTableVariable,...
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@(x) any(validatestring(x,expectedTableVariable)));
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addParameter(p,'mode',defaultMode,...
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@(x) any(validatestring(x,expectedMode)));
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addParameter(p,'showFigures',defaultShowFigures,...
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@(x) any(validatestring(x,expectedShowFigures)));
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addParameter(p,'energyScale',defaultEnergyScale,...
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@(x) any(validatestring(x,expectedEnergyScale)));
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parse(p,DataTable,varargin{:});
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% check input (all elements of input variable need to have non-zero size)
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if ~all(cell2mat(cellfun(@size,p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable),'UniformOutput',false)),'all')
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disp('The table variable appears to be empty. I quit now')
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error('The table variable appears to be empty.')
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end
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% add empty table variables (if they don't exist)
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existColumn = strcmp('logBackgroundRange',DataTable.Properties.VariableNames);
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if ~any(existColumn)
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DataTable.logBackgroundRange = NaN(size(DataTable,1),2);
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end
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existColumn = strcmp('logBackgroundMode',DataTable.Properties.VariableNames);
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if ~any(existColumn)
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DataTable.logBackgroundMode = cellstr(repmat(' ',size(p.Results.DataTable,1),1));
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end
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existColumn = strcmp('logBackgroundDate',DataTable.Properties.VariableNames);
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if ~any(existColumn)
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DataTable.logBackgroundDate = cellstr(repmat(' ',size(p.Results.DataTable,1),1));
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end
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% add empty variable to table
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existColumn = strcmp('spectrum_countsNorm',DataTable.Properties.VariableNames);
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if ~any(existColumn)
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DataTable.spectrum_countsNorm = cell(size(DataTable,1),1);
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end
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% repeat this for all input.
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for ii = 1:size(p.Results.DataTable(p.Results.tableSelection,:),1)
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if startsWith(p.Results.mode,'linfit')
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ft = fittype( 'poly1' );
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elseif contains(p.Results.mode,'exponential')
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ft = fittype( 'exp2' );
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end
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if contains(p.Results.energyScale,'kinetic')
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if ~startsWith(p.Results.mode,'mean')
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[xData, yData] = prepareCurveData(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii},p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
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excludedPoints = excludedata( xData, yData, 'domain',[p.Results.energyStart(1) p.Results.energyEnd(1)] );
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if size(p.Results.energyStart,2) ==2 && size(p.Results.energyEnd,2) ==1
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excludedPointsEins = excludedPoints;
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clearvars excludedPoints
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excludedPointsZwei = excludedata( xData, yData, 'domain',[xData(1) p.Results.energyStart(2)] );
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excludedPoints = excludedPointsEins & excludedPointsZwei;
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elseif size(p.Results.energyStart,2) ==2 && size(p.Results.energyEnd,2) ==2
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excludedPointsEins = excludedPoints;
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clearvars excludedPoints
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excludedPointsZwei = excludedata( xData, yData, 'domain',[xData(1) p.Results.energyStart(2)] );
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excludedPointsDrei = excludedata( xData, yData, 'domain',[p.Results.energyEnd(2) xData(end)] );
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excludedPoints = excludedPointsEins & excludedPointsZwei & excludedPointsDrei;
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elseif size(p.Results.energyStart,2) ==1 && size(p.Results.energyEnd,2) ==2
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excludedPointsEins = excludedPoints;
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clearvars excludedPoints
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excludedPointsZwei = excludedata( xData, yData, 'domain',[p.Results.energyEnd(2) xData(end)] );
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excludedPoints = excludedPointsEins & excludedPointsZwei;
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end
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opts = fitoptions( 'Method', 'NonlinearLeastSquares','Exclude', ~excludedPoints );
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opts.Display = 'Off';
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% Fit model to data.
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[fitresult, ~] = fit( xData, yData, ft, opts );
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if contains(p.Results.showFigures,'on')
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% Plot fit with data.
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figure( 'Name', 'untitled fit 1' );
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plot( fitresult, xData, yData, ~excludedPoints );
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% legend( h, 'y vs. x', 'Excluded y vs. x', 'untitled fit 1', 'Location', 'NorthEast', 'Interpreter', 'none' );
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% Label axes
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xlabel( 'kinetic energy [eV]', 'Interpreter', 'none' );
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ylabel( 'PE intensity', 'Interpreter', 'none' );
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grid on
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title(p.Results.DataTable(p.Results.tableSelection,:).name{ii},'Interpreter','none')
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end
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if endsWith(p.Results.mode,'divide')
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tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}./fitresult(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii});
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else
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tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}-fitresult(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii});
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end
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elseif startsWith(p.Results.mode,'mean')
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b_1 = find(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii} >= p.Results.energyStart,1);
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b_2 = find(p.Results.DataTable(p.Results.tableSelection,:).scientaEkin_eV{ii} >= p.Results.energyEnd,1);
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if b_2 == 1
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b_2=10;
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end
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b_mean = mean(p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}(b_1:b_2),'omitnan');
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tmp(ii,1) = cellfun(@(x) x-b_mean,p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)(ii),'UniformOutput',false); %#ok<*AGROW>
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end
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elseif contains(p.Results.energyScale,'binding')
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if ~startsWith(p.Results.mode,'mean')
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[xData, yData] = prepareCurveData(p.Results.DataTable(p.Results.tableSelection,:).bindingEnergy_eV{ii},p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
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% Set up fittype and options.
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excludedPoints = ~excludedata( xData, yData, 'domain',[p.Results.energyStart(1) p.Results.energyEnd(1)] );
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if size(p.Results.energyStart,2) ==2 && size(p.Results.energyEnd,2) ==1
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excludedPointsEins = excludedPoints;
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clearvars excludedPoints
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excludedPointsZwei = ~excludedata( xData, yData, 'domain',[xData(end) p.Results.energyStart(2)] );
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excludedPoints = excludedPointsEins | excludedPointsZwei;
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elseif size(p.Results.energyStart,2) ==2 && size(p.Results.energyEnd,2) ==2
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excludedPointsEins = excludedPoints;
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clearvars excludedPoints
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excludedPointsZwei = ~excludedata( xData, yData, 'domain',[xData(end) p.Results.energyStart(2)] );
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excludedPointsDrei = ~excludedata( xData, yData, 'domain',[p.Results.energyEnd(2) xData(1)] );
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excludedPoints = excludedPointsEins | excludedPointsZwei |excludedPointsDrei ;
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elseif size(p.Results.energyStart,2) ==1 && size(p.Results.energyEnd,2) ==2
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excludedPointsEins = excludedPoints;
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clearvars excludedPoints
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excludedPointsZwei = ~excludedata( xData, yData, 'domain',[p.Results.energyEnd(2) xData(1)] );
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excludedPoints = excludedPointsEins | excludedPointsZwei;
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end
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opts = fitoptions( 'Method', 'NonlinearLeastSquares','Exclude', excludedPoints );
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opts.Display = 'Off';
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% Fit model to data.
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[fitresult, ~] = fit( xData, yData, ft, opts );
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if contains(p.Results.showFigures,'on')
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% Plot fit with data.
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figure( 'Name', 'untitled fit 1' );
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plot( fitresult, xData, yData, excludedPoints );
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% legend( h, 'y vs. x', 'Excluded y vs. x', 'untitled fit 1', 'Location', 'NorthEast', 'Interpreter', 'none' );
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% Label axes
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xlabel( 'binding energy [eV]', 'Interpreter', 'none' );
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ylabel( 'PE intensity', 'Interpreter', 'none' );
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grid on
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title(p.Results.DataTable(p.Results.tableSelection,:).name{ii},'Interpreter','none')
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ax = gca;
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ax.XDir = 'reverse';
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end
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if endsWith(p.Results.mode,'divide')
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tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}./fitresult(p.Results.DataTable(p.Results.tableSelection,:).bindingEnergy_eV{ii});
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else
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tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}-fitresult(p.Results.DataTable(p.Results.tableSelection,:).bindingEnergy_eV{ii});
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end
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elseif startsWith(p.Results.mode,'mean')
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b_1 = find(p.Results.DataTable(p.Results.tableSelection,:).bindingEnergy_eV{ii} <= p.Results.energyStart,1);
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b_2 = find(p.Results.DataTable(p.Results.tableSelection,:).bindingEnergy_eV{ii} <= p.Results.energyEnd,1);
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if b_2 == 1
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b_2=10;
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end
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b_mean = mean(p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}(b_2:b_1),'omitnan');
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tmp(ii,1) = cellfun(@(x) x-b_mean,p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)(ii),'UniformOutput',false);
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end
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elseif contains(p.Results.energyScale,'xRay')
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if contains(p.Results.mode,'linfit') % LINEAR FIT
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% Fit: 'untitled fit 1'.
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[xData, yData] = prepareCurveData( p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}, ...
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p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
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% Set up fittype and options.
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ft = fittype( 'poly1' );
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excludedPoints = excludedata( xData, yData, 'domain',[p.Results.energyStart p.Results.energyEnd] );
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fo = fitoptions('Exclude', excludedPoints);
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% Fit model to data.
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[fitresult, ~] = fit( xData, yData, ft, fo );
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if contains(p.Results.showFigures,'on')
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% Plot fit with data.
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figure( 'Name', 'fit pre-edge' );
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plot( fitresult, xData, yData, excludedPoints );
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xlabel('Photon Energy eV')
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ylabel('partial A-M.E.Y.')
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grid on
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title(p.Results.DataTable(p.Results.tableSelection,:).name{ii},'Interpreter','none')
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end
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tmp{ii,1} = p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii}-fitresult(p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii});
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elseif contains(p.Results.mode,'mean') % mean
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if p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}(1) < p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}(end)
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% prepare Data
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[xData, yData] = prepareCurveData( p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}, ...
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p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
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% MEAN
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b_1 = find(xData >= p.Results.energyStart,1);
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b_2 = find(xData >= p.Results.energyEnd,1);
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b_mean = mean(yData(b_1:b_2));
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elseif p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}(1) > p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}(end)
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% prepare Data
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[xData, yData] = prepareCurveData( p.Results.DataTable(p.Results.tableSelection,:).xRayEkin_eV{ii}, ...
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p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable){ii});
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% MEAN
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b_1 = find(xData <= p.Results.energyStart,1);
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b_2 = find(xData <= p.Results.energyEnd,1);
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b_mean = mean(yData(b_2:b_1));
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else
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disp('Warning: Issue with NEXAFS data or energies')
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end
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tmp(ii,1) = cellfun(@(x) x-b_mean,p.Results.DataTable(p.Results.tableSelection,:).(p.Results.tableVariable)(ii),'UniformOutput',false);
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end
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end
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end
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% fill selected rows
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if endsWith(p.Results.mode,'divide')
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DataTable(p.Results.tableSelection,:).spectrum_countsNorm = tmp;
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else
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DataTable(p.Results.tableSelection,:).(p.Results.tableVariable) = tmp;
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end
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% write log to table
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DataTable.logBackgroundMode(p.Results.tableSelection,:) = cellstr(repmat(p.Results.mode,size(p.Results.DataTable(p.Results.tableSelection,:),1),1));
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DataTable.logBackgroundRange(p.Results.tableSelection,:) = repmat([p.Results.energyStart(1) p.Results.energyEnd(1)],size(p.Results.DataTable(p.Results.tableSelection,:),1),1);
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DataTable.logBackgroundDate(p.Results.tableSelection,:) = cellstr(repmat(datestr(now),size(p.Results.DataTable(p.Results.tableSelection,:),1),1));
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end |