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7. Array Functions

S-Lang includes many intrinsic functions that operate on arrays. The additional functions described here are defined in arrayfuns.sl.

7.1 rearrange

Synopsis

Rearrange the elements of a 1-d array or list.

Usage

rearrange (A, indices)

Description

This function performs an in-place rearrangment of the the elements of an array according to the specified permutation, represented by the indices argument. The indices array is assumed to contain unique integers in the range [0,length(A)-1].

Notes

The function modifies the elements of the indices array while it performs the rearrangement. The values will get restored upon return from function.

The algorithm used was derived from the DPPERM function, which is part of the SLATEC package. See http://gams.nist.gov/cgi-bin/serve.cgi/Package/SLATEC.

See Also

array_reverse, array_swap

7.2 reverse

Synopsis

Reverse the elements of a 1-d array

Usage

Array_Type reverse (Array_Type A)

Description

The reverse function reverses the elements of a 1-d array and returns the result.

See Also

shift

7.3 shift

Synopsis

Shift the elements of a 1-d array

Usage

Array_Type shift (Array_Type A, Int_Type n)

Description

The shift function shifts the elements of an array by a specified amount and returns the result. If n is positive, the ith element of the array will be shifted to the position i-n of the array. Elements for which i-n is less than 0 will be moved to the end of the array.

Example

   A = [1,2,3,4,5,6,7,8,9];
   B = shift (A, 3);          % ==> B = [4,5,6,7,8,9,1,2,3];
   C = shift (A, -1);         % ==> C = [9,1,2,3,4,5,6,7,8];

Notes

It many ways rotate would be a better name for this function.

See Also

reverse, transpose


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