Programmer Guide/Command Reference/EVAL/shuffle: Difference between revisions

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Create a ''shuffled'' version of a set.
Create a ''shuffled'' version of a set.
 
;Usage: <code>shuffle(''x'' {, ''n'' {, ''once'' { ''seed''}}})</code>
;Usage: '''<code>shuffle(''x'' {, ''n'' {, ''once'' { ''seed''}}})</code>'''
:;''x'': the set to be shuffled; must be a vector or matrix
:;''x'': the set to be shuffled; must be a vector or matrix
:;''n'': the number of row exchanges applied top ''x''; <code>0 < ''n''</code> (default=<code>nrow(''x'')/2)
:;''n'': the number of row exchanges applied top ''x''; <code>0 < ''n''</code> (default=<code>nrow(''x'')/2</code>)
:;''once'': if not equal ''0'' the position of a row must not be changed more than 1 times, otherwise the number of position changes of a row is not limited
:;''once'': change row position only once
:;''seed'': if this value is not equal ''0'', it is used to initialize the random number generator used to select the rows to be exchanged
::''once''=0: the number of exchanges of a row is not limited
 
::''once''&ne;0: the number of exchanges of a row is limited to 1
 
:;''seed'': if this value is not equal ''0'', it is used to initialize the random number generator which generates the indices of the rows to be exchanged
;Result: A vector with length ''m'', containing the indices of the selected elements of the set.
;Result: The result has the same type and content as ''x'', but the order of the rows is changed (''shuffled'') randomly. To shuffle the row indices, ''n'' times two randomly selected rows are exchanged.
:It is assumed that the set is indexed from 0 to ''n''-1 (i.e. the number of elements). The result vector can be applied as an index list on the set to extract the corresponding elements.
;See also: [[../rand|rand]], [[../grand|grand]], [[../sample|sample]], [[../sort|sort]]
 
;See also: [[Programmer_Guide/Command_Reference/EVAL/rand|rand]], [[Programmer_Guide/Command_Reference/EVAL/sample|grand]], [[Programmer_Guide/Command_Reference/EVAL/shuffle|shuffle]]


[[Programmer_Guide/Command_Reference/EVAL#Functions|<function list>]]
[[../#Functions|<function list>]]

Latest revision as of 19:07, 21 April 2011

Create a shuffled version of a set.

Usage
shuffle(x {, n {, once { seed}}})
x
the set to be shuffled; must be a vector or matrix
n
the number of row exchanges applied top x; 0 < n (default=nrow(x)/2)
once
change row position only once
once=0: the number of exchanges of a row is not limited
once≠0: the number of exchanges of a row is limited to 1
seed
if this value is not equal 0, it is used to initialize the random number generator which generates the indices of the rows to be exchanged
Result
The result has the same type and content as x, but the order of the rows is changed (shuffled) randomly. To shuffle the row indices, n times two randomly selected rows are exchanged.
See also
rand, grand, sample, sort

<function list>

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