CopyIndex

CopyIndex(i)

Makes a copy of the values in «i» and returns these as a list. «i» must be a list or 1-D array. In the case of a 1-D array, the values in the array itself are returned, essentially removing the index from the array (converting the array to a list, or equivalently, to an array with an implicit dimension).

CopyIndex is most often used to make a copy of an existing index for the purpose of defining a new index with the same index values. For example, if you need to represent a square matrix, you will need two indexes with the same length -- defining the second using CopyIndex allows the second index to automatically adapt if the first index changes.

Library

Array Functions

Examples

Index Origins
 Definition := [ 'London', 'New York', 'Tokyo', 'Paris', 'Delhi' ]
 
Index Destinations
 Definition := CopyIndex( Origins )
 
Variable Flight_times := Table(Origins,Destinations)

Note: If you were to define Destinations simply as Origins, without using CopyIndex(), Destinations would be indexed by Origins, and the resulting table would have only one dimension index. By defining Destinations with CopyIndex(), it becomes a separate index, so that the table has two dimensions.

Notes

When defining a local index using Index..Do, a CopyIndex is implicitly performed, so an explicit call to CopyIndex is unnecessary.

See Also

• Index..Do
• Subset
• Array

User Guide

Makes a copy of the values of index i, to be assigned to a new index variable, global or local. For example, suppose you want to create a matrix of distances between a set of origins and destinations, which are each the same set of cities:

Index Origins
Definition:= ['London', 'New York', 'Tokyo', 'Paris', 'Delhi']
Index Destinations
Definition:= CopyIndex(Origins)

Variable Flight_times := Table(Origins, Destinations)

If you defined Destinations as equal to Origins, without using Copyindex(), Destinations would be indexed by Origins, and the resulting table would have only one dimension index. By defining Destinations with CopyIndex(), it becomes a separate index, so that the table has two dimensions.