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Straightforward COPY and PASTE functions

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Straightforward COPY and PASTE functions

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25 Jun 2010 (Updated )

Allows very simple manual exchange with other applications through the clipboard.

Editor's Notes:

This file was selected as MATLAB Central Pick of the Week

paste(dec,sep,lf)
% PASTE copies the content of the clipboard to a variable; creates a
% string, a cell array, or a numerical array, depending on content.
%
% Usage:
%   x = paste;
%   x = paste(dec,sep,lf);
%
% The program will try to create an array. For this to succeed, the
% material that is passed from the clipboard must be a tab delimited array,
% such as produced by Excel's copy command. If the content does not have
% this structure, the program simply returns a string. If the content is an
% array, x will be a numerical array if all its components qualify as
% numerical. If not, it will be a cell array.
%
% Optional arguments:
%   dec   Single character that indicates the decimal separator. Default is
%         the period ('.').
%   sep   Single character that indicates how horizontal neigbors of a
%         matrix or cell array are separated. Default is the tabulator code
%         (char 9).
%   lf    Single character that indicates how rows are separated.(lf stands
%         for line feed). Default is the line feed code (char 10).
%
% Examples:
%
% 1) If the clipboard contains 'George's job is to chop wood.', then
%    x = paste produces x = 'George's job is to chop wood.'
%
% 2) If the content of the clipboard is a simple text with multiple lines
%    (copied from Notepad or Word or similar), then x = paste produces a
%    cell array with one column and one row per line of the input so each
%    line of text will be separated in different cells. For example, if you
%    copy the follwing text from some other program,
%
%       Manche meinen lechts und rinks kann man nicht velwechsern.
%       Werch ein Illtum!
%
%    then, in Matlab, x = paste produces a 2x1 cell array with
%
%       x{1} = 'Manche meinen lechts und rinks kann man nicht velwechsern.'
%       x{2} = 'Werch ein Illtum!'
%
%    [Note: x = clipboard('copy') would produce just a string in this case,
%    not an array of stringcells, so choose the code that is most useful for
%    your purpose.]
%
% 3) However, if your text contains an equal number of tabs on each line,
%    for instance because you've copied something like this from Word,
%      1  ->  item 1
%      2  ->  item 2
%      3  ->  item 3
%    where -> denotes TABs, then x = paste produces a 3x2 cell array,
%      x = 
%         [1]    'item 1'
%         [2]    'item 2'
%         [3]    'item 3'
%
% 4) If the clipboard contains an array of cells, e.g.
%         1  2  3
%         4  5  6
%    for instance by copying these six cells from an Excel spreadsheet,
%    then x = paste makes a 2x3 array of doubles with the same content.
%    The same is true if there are NaN cells. So if the Excel excerpt was
%         1     2     3
%         4   #N/A    6
%    then x =
%         1     2     3
%         4   NaN     6
%
% 5) If the cell collection in the clipboard is
%         A  1.3  NaN
%    then x will not be a numerical array, but a 1x3 cell array, with
%     x = 
%        'A'    [1.3000]    [NaN]
%    so x{1} is a string, but x{2} and x{3} are doubles.
%
% 6) If the clipboard contains '1,2', then x=paste with no arguments will
%    be 12 (because Matlabs str2double('1,2') interprets this as the number
%    12). However, x=paste(',') will return 1.2
%
% 7) If the clipboard contains '1,2 & 100', then x=paste with no arguments
%    will return just the string '1,2 & 100'. x=paste(',','&'), on the
%    other hand, will return a numerical array [1.2, 100].
%
% Here is a practical example:
% ----------------------------
%   In Excel, select your data, say, a sample of observations organized in
%   a few columns. Place them into the clipboard with Ctrl-C.
%   Now switch to Matlab and say
%       x = paste;
%   This puts the data that you copied in Excel into a variable x in
%   Matlab's workspace.
%   Next, you can analyze the data. For instance, compute the principal
%   components (an analysis that is not readily available in Excel), and
%   push the result back into the clipboard,
%       [c,s] = princomp(x);
%       copy(s)
%   Now, back in Excel, you can paste the result into your spreadsheet with
%   Ctrl-V.
%   
% This program was selected 'Pick of the Week' on March 7, 2014. :-)
%
% Author : Yvan Lengwiler
% Release: $1.51$
% Date   : $2014-03-19$
%
% See also COPY, CLIPBOARD

% History:
% 2010-06-25	correction of a bug that occurred with multiple string
%               cells on a single line.
% 2011-06-05	Simplified detection of line feeds.
% 2011-06-22	Removal of an unused variable.
% 2012-02-03	Tries to identify non-conventional decimal and thousand
%               separators.
% 2013-03-19	Three optional arguments (dec, sep, and lf).
% 2014-02-21    Corrected a bug found by Jiro Doke. (Thanks, Jiro)
% 2014-03-19    Bud fix, thanks to Soren Preus.

function x = paste(dec,sep,lf)
    
    % handle optional parameters
    if nargin < 3
        lf = char(10);  % default is line feed (char 10)
    end
    if nargin < 2
        sep = char(9);  % default is tabulator (char 9)
    end
    if nargin < 1
        dec = '.';      % default is a period '.'
    end
    
    % get the material from the clipboard
    p = clipboard('paste');
    
    % get out of here if nothing usable is in the clipboard
    % (Note: MLs 'clipboard' interface supports only text, not images or
    % the like.)
    if isempty(p)
        x = [];
        return;
    end
    
    % find linebreaks
    if p(end) ~= lf
        p = [p,lf];               % append linefeed if missing
    end
    posLF = find(ismember(p,lf)); % find linefeeds
    nLF   = numel(posLF);               % count linefeeds
    
    % break into separate lines; parse each line by tab
    lines  = cell(nLF,1);
    posTab = cell(nLF,1);
    numTab = zeros(nLF,1);
    last = 0;
    for i = 1:nLF
        lines{i}  = [p(last+1:posLF(i)-1),sep]; % append a tabulator
        last      = posLF(i);
        tabs      = ismember(lines{i},sep);     % find tabulators
        aux       = linspace(1,numel(lines{i}),numel(lines{i}));
        posTab{i} = aux(tabs);                  % positions of tabs
        numTab(i) = sum(tabs(:));               % count tabs in line
    end

    % is it an array (i.e. a rectangle of cells)?
    isArray = true;
    i = 1;
    while isArray && i <= nLF
        isArray = (numTab(i) == numTab(1));
        i = i+1;
    end
    
    if ~isArray
        % it's not an array, so just return the raw content of the clipboard
        x = p;
        % Note: A simple single or multi-line text with no tabs *does*
        % qualify as an array, so the program splits such content line-wise
        % into a one-column cell array.
    else
        % it is an array, so put it into a Matlab cell array
        isNum = true;   % will remain true if it is never switched off below
        x = cell(nLF,numTab(1));
        for i = 1:nLF
            last = 0;
            pos = posTab{i};
            for j = 1:numTab(1);
                x{i,j} = lines{i,1}(last+1:pos(j)-1);
                % try to make numerical cells if possible
                if ismember(x{i,j},{'NaN','#N/A'})
                    x{i,j} = NaN;
                else
                    aux = x{i,j};   % copy to work on
                    % deal with decimal and thousand separators
                    if dec ~= '.'
                        aux = strrep(aux,dec,'.');  % replace decimal
                                                    % separators with periods
                    else
                        if numel(strfind(aux,'''')) > 0
                            % remove apostrophes
                            aux = strrep(aux,'''','');
                            % if it is a number, it is formatted conventionally
                        else
                            % determine if decimal separator is comma and
                            % thousand separator is period
                            posComma  = strfind(aux,',');
                            posPeriod = strfind(aux,'.');
                            if numel(posComma) == 1 && numel(posPeriod) > 0
                                if all(mod(posComma-posPeriod,4) == 0) && ...
                                        posComma > posPeriod(end)
                                    % this is potentially a non-conventionally
                                    % formatted number: remove periods first,
                                    % then replace comma with period
                                    aux = strrep(aux,'.','');
                                    aux = strrep(aux,',','.');
                                end
                            end
                        end
                    end
                    % determine if the cell is numerical
                    aux = str2double(aux);  % try to make a double
                    if isnan(aux)
                        % this cell is not numerical (turn off switch for
                        % later)
                        isNum = false;
                    else
                        % str2double has produced a ligit number
                        x{i,j} = aux;
                    end
                end
                last = pos(j);
            end
        end
        if isNum	% make a numerical array if possible
            x = cell2mat(x);
        end
    end
    
    % remove cell encapsulation if there is only one cell
    if numel(x) == 1
        try
            x = x{1};
        end
    end

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