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// Scilab ( http://www.scilab.org/ ) - This file is part of Scilab
// Copyright (C) 2003 - INRIA - Carlos Klimann
//
// 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_V2.1-en.txt
//
function s = samplef(n, X, f, orient)
//
//This function gives s, a vector of length n. It contains
//a sample of n extractions, with replacement, from the
//vector (or matrix) X, each element counted with the
//frequency given by the corresponding value in vector f.
//
//s = samplef(n, X, f) (or s = samplef(n, X, f, '*')) returns a
//vector s whose values are a random sample of n values from
//X, each value with a probability to be sampled
//proportional to the corresponding value of f, extracted
//with replacement, from X. f must have same length than X.
//
//s = samplef(n, X, f, 'r') (or, equivalently,
//s = samplef(n, X, f, 1)) returns a matrix of type
//size(X, 'r')xn. It contains a random sample of n rows from
//X, each row with a probability to be sampled proportional
//to the corresponding value of f, extracted with
//replacement, from the rows of X. The length of f must be
//equal to the number of rows of X.
//
//s = samplef(n, X, f, 'c') (or, equivalently,
//s = samplef(n, X, f, 2)) returns a matrix of type
//nxsize(X, 'c'). It contains a random sample of n columns
//from X, each column with a probability to be sampled
//proportional to the corresponding value of f, extracted
//with replacement, from the columns of X. The length of f
//must be equal to the number of columns of X.
//
[lhs, rhs] = argn(0)
if rhs < 3 | rhs > 4 then error(msprintf(gettext("%s: Wrong number of input arguments: %d to %d expected.\n"), "samplef", 3, 4)), end
if X == [] then s = []; return; end
// Frequencies cannot be negative
if ~and(f >= 0)
error(msprintf(_("%s: Wrong value for input argument #%d: Non-negative values expected.\n"), fname, 3))
end
// Setting default value for 4th argument
if rhs == 3 then
orient = "*"
end
sizx = size(X)
if orient == "*" then
if size(f, "*") <> prod(sizx) then
error(msprintf(gettext("%s: Wrong size for input argument #%d and #%d: Same size expected.\n"), "samplef", 2, 3)),
end
//Strip X of 0 frequency values
X(find(f==0)) = [];
f(find(f==0)) = [];
val = cumsum([0; f(:)])
y = grand(n, 1, "unf", 0, val($))
ind = dsearch(y, val, "c")
s = X(ind)
s_size = size(s, '*')
s = matrix(s, 1, s_size) //consistently returns s in a line vector when called without row or column orientation;
return
end
if orient == "r"|orient == 1 then
if size(f, "*") <> sizx(1) then
error(msprintf(gettext("%s: Wrong size for input argument #%d: Same number of rows of the second input argument expected.\n"), "samplef", 3)),
end
//Strip X of 0 frequency values
X(find(f==0), :) = [];
f(find(f==0)) = [];
val = cumsum([0; f(:)])
y = grand(n, 1, "unf", 0, val($))
ind = dsearch(y, val, "c")
s = X(ind, :)
return
end
if orient == "c"|orient == 2 then
if size(f, "*") <> sizx(2) then
error(msprintf(gettext("%s: Wrong size for input argument #%d: Same number of columns of the second input argument expected.\n"), "samplef", 3)),
end
//Strip X of 0 frequency values
X(:, find(f==0)) = [];
f(find(f==0)) = [];
val = cumsum([0; f(:)])
y = grand(n, 1, "unf", 0, val($))
ind = dsearch(y, val, "c")
s = X(:, ind)
return
end
error(msprintf(gettext("%s: Wrong value for input argument #%d: ''%s'', ''%s'', ''%s'', %d or %d expected.\n"), "orient", 4, "*", "r", "c", 1, 2))
endfunction
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