Sets - Extracting Subsets
Instead of specifying single index values to retrieve single elements, subsets can be retrieved by listing muliple values and/or ranges. In some other programming langauges, this feature is known as slicing. The range operator '..' is available to specify a range. If no value prcedes the range operator, than 0 is assumed. If no value follows the range operator, then the last character is assumed. The range operator '..' is available to specify a range. The result will always be returned in a set, even if the subset specified results in just one element, e.g. {a,b,c}{1..1} returns {b} and not b. Negative indexing is supported.
a[] = { a,b,c, {d,e,f}, g }; // Assign a set to variable a[]
echo( "4 elements : ", a[]{3,1,2,1} ); // Retrieves 4 elements (2 of them repeating here)
echo( "2nd to 2nd last : ", a[]{1..3} ); // Use a range
echo( "2nd to 2nd last : ", a[]{1..-2} ); // Same output
echo( "2nd to 2nd last : ", a[]{-4..3} ); // Same output (-4 = 4th last or 2nd element)
echo( "1st element : ", a[]{0..0} ); // Return 1st element, but in a subset and not alone
echo( "Combinations : ", a[]{2..4,1} ); // Combination of simple values and ranges
echo( "First three elements : ", a[]{..2} ); // Returns first 3 elements
echo( "Last three elements : ", a[]{-3..} ); // Returns last 3 elements (negative indexing used here)
echo( "Entire set : ", a[]{..} ); // Returns entire set
echo( "2nd element as subset : ", a[]{1..1} ); // Must specify 1..1 (a range) to distinguish from __set indexing__.4 elements : {{'d','e','f'},'b','c','b'}
2nd to 2nd last : {'b','c',{'d','e','f'}}
2nd to 2nd last : {'b','c',{'d','e','f'}}
2nd to 2nd last : {'b','c',{'d','e','f'}}
1st element : {'a'}
Combinations : {'c',{'d','e','f'},'g','b'}
First three elements : {'a','b','c'}
Last three elements : {'c',{'d','e','f'},'g'}
Entire set : {'a','b','c',{'d','e','f'},'g'}
2nd element as subset : {'b'}