// Copyright (C) 2018 - IIT Bombay - FOSSEE
// This file must be used under the terms of the CeCILL.
// This source file is licensed as described in the file COPYING, which
// you should have received as part of this distribution.  The terms
// are also available at
// http://www.cecill.info/licences/Licence_CeCILL_V2-en.txt
// Author: Abinash Singh Under FOSSEE Internship
// Modifieded by: Abinash Singh Under FOSSEE Internship
// Last Modified on : 3 Feb 2024
// Organization: FOSSEE, IIT Bombay
// Email: toolbox@scilab.in
/*
Calling Sequence :
    prepad (x, l)
    prepad (x, l, c)
    prepad (x, l, c, dim)

Prepend the scalar value c to the vector x until it is of length l. If c is not given, a value of 0 is used.
If length (x) > l, elements from the beginning of x are removed until a vector of length l is obtained.
If x is a matrix, elements are prepended or removed from each row.
If the optional argument dim is given, operate along this dimension.
If dim is larger than the dimensions of x, the result will have dim dimensions.
*/
function res = prepad(x,l,c,dim)
    if nargin < 2 then 
        error("Usage :  postpad(x,l,c(optional),dim(optional))")
    end
    if nargin < 3 then 
        c = 0 ;
    end
    if nargin < 4 then 
        dim = find(size(x)>1)
        if isempty(dim) then dim = 2 end
        if isvector(dim) then dim = dim(1) end
    end

    if l < size(x,dim) then
        if isvector(x) then 
            start = length(x) - l+1;
            res=x(start:$)
            return;
        else
            error("prepad : l must be greter than dim size for matrices")
        end
        
    end
    
    if dim == 1 then 
        res = [ c* ones( l - size(x,1) , size(x,2)) ; x]
    elseif dim == 2 then 
        res = [ c* ones( size(x,1) , l - size(x,2)) x]
    else
        error("prepad : Invalid value for arg dim 1 or 2 expected")
    end
endfunction

/*
#test for row vectors
prepad([1 2 3 4],6) 
prepad([1 ;2 ;3 ;4],6) 
prepad([1 2 3 4;5 6 7 8;9 10 11 12],6) 
prepad([1 2 ;3 4;5 6],6,-1) 

// FIXME : Tests for 2d and high dimesnsional matrices
*/