The uniq operator returns a result array with consecutive duplicate values removed.

Synopsis

uniq(array[, chunk_size: chunk_size]);

Summary

The uniq operator takes as input a one-dimensional array, and returns an array with all consecutive duplicate values removed. It is analogous to the Unix uniq command.

Note the following:

The input array requires a single attribute of any type and a single dimension.
To remove all duplicates and not just consecutive ones, sort the input data first.
The result array has the same attribute name as the input array; its sole dimension is named i, starting at 0; and has a default chunk size of one million (1,000,000). For a different chunk size, use the optional named parameter, chunk_size.
The result array has no null values.

Examples

Using the Operator

To demonstrate uniq operator, do the following:

Create an array with duplicates:

AFL% store(build(<v:int64>[i=0:5], '[(8),(8),(42),(8),(8),(17)]', true), A);

The output is:

{i} v
{0} 8
{1} 8
{2} 42
{3} 8
{4} 8
{5} 17

Eliminate the consecutive duplicates. Note that A was not already sorted, so two values of eight still remain, one for each run of consecutive eights.
```
AFL% uniq(a);
```
The output is:
```
{i} v
{0} 8
{1} 42
{2} 8
{3} 17
```
Eliminate all duplicates, by sorting the input first.
```
AFL% uniq(sort(A)); 
```
The output is:
```
{i} v
{0} 8
{1} 17
{2} 42
```
Remove the array:
```
AFL% remove(A);
```