List/Set.at(N)

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List.at(N)

This returns the Nth value of the List as a string. List can be either Set or List type attributes (or string literal, regex, or expression equivalents thereof).

Note: for accessing look-up tables, use list.lookup().

The operator is zero-based, i.e. an N value of 0 returns the first list item, an N of 1 returns value #2, etc. If the value of N exceeds the number of items in the list an empty string (blank value) is returned. A negative number returns an item numbering in reverse, but one-based not zero-based, so '-1' returns the last item on the list, '-2' the last but one item, etc.

Examples (where $MyList is "ant;bee;cow"):

$MyString = $MyList.at(0); returns "ant"

$MyString = "XX;YY;ZZ".at(2); returns "ZZ"

$MyString = $MyList.at(5); returns "" (nothing) 

$MyString = $MyList.at(-2); returns "bee"

See also the more recent List/Set[N] usage.

Legacy use (pre-v8)

List.at("key")

This usage is deprecated, use List/Set.lookup("key") instead. The remainder of this section is for explanation of legacy code use only.

The .at() function is also useful for accessing values from look-up tables by providing the relevant key. Consider a look-up list:

$RegionList="AL:South;AK:NorthWest;default:North"; 

This allows actions like:

$Region=$RegionList.at("AL"); 

or

$Region=$RegionList.at($State);