Difference between revisions of "Unique"

Revision as of 00:59, 21 November 2015

Unique(a, i)

Returns a maximal subset of index «i» such that each indicated slice of array «a» along «i» is unique.

Unique can be used to remove duplicate slices from an array, or to identify a single member of each equivalence class.

Examples

Let DataSet →

	Field ▶
PersonNum ▼	LastName	FirstName	Company
1	Smith	Bob	Acme
2	Jones	John	Acme
3	Johnson	Bob	Floorworks
4	Smith	Bob	Acme

Then

Unique(DataSet, PersonNum) → [1, 2, 3]
code>Unique(DataSet[Field='Company'], PersonNum) → [1, 3]

Optional parameters

Position

By default, Unique returns the elements of the index. Setting the optional parameter «position» equal true (position: true) will return the positions of the elements in «i» , rather than the elements themselves (see Associative vs. Positional Indexing).

CaseInsensitive

When applying Unique to text values, values are considered by default in a case-sensitive fashion, for example, "Apple" and "apple" are considered distinct elements.

Specifying caseInsensitive: true ignores differences in upper and lower case in text values when determining if values are unique.

@@ Line 1: / Line 1: @@
 [[Category:Functions that create lists]]
+[[Category:Array Library]]
 [[Category:Doc Status C]] <!-- For Lumina use, do not change -->
-Returns a maximal subset of I such that each indicated slice of A along I is unique.
+==Unique(a, i)==
+Returns a maximal subset of index «i» such that each indicated [[slice]] of array «a»  along «i»  is unique.
-= Declaration =
+[[Unique]] can be used to remove duplicate slices from an array, or to identify a single member of each equivalence class.
-  Unique(A : Array[I] ; I : Index )
+== Examples ==
+Let
+<code>DataSet →</code>
+  {| class="wikitable"
+!
+!colspan="3" | Field ▶
+|-
+!PersonNum '''▼'''
+!LastName
+!FirstName
+!Company
+|-
+! scope="row" |1
+|Smith
+|Bob
+|Acme
+|-
+! scope="row" |2
+|Jones
+|John
+|Acme
+|-
+! scope="row" |3
+|Johnson
+|Bob
+|Floorworks
+|-
+! scope="row" |4
+|Smith
+|Bob
+|Acme
+|}
-= When to use:=
+Then
+ Unique(DataSet, PersonNum) → [1, 2, 3]
+ code>Unique(DataSet[Field='Company'], PersonNum) → [1, 3]
-Use Unique to remove duplicate slices from an array, or to identify a single member of each equivalence class.
+== Optional parameters ==
+=== Position ===
+By default, [[Unique]] returns the elements of the index.  Setting the optional parameter «position»  equal ''true'' (<code>position: true</code>) will return the positions of the elements in «i» , rather than the elements themselves (see [[Associative vs. Positional Indexing]]).
-= See also =
+===CaseInsensitive===
+When applying [[Unique]] to text values, values are considered by default in a case-sensitive fashion,  for example, "Apple" and "apple" are considered distinct elements.
+Specifying ''caseInsensitive: true'' ignores differences in upper and lower case in text values when determining if values are unique.
+== See also ==
 * [[SortIndex]]
 * [[Subset]]