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Documentation for: extend.r


REBOL

Extend

Author: Vincent Ecuyer
Date: 31-Jan-2013
File: %extend.r

Contents:

1. Purpose
2. Usage
3. Examples

1. Purpose

Extends a series with sequential or duplicate values.

2. Usage

extend/to/cut value (series!) length (integer!)

with:

Argument

Type

Usage

value

series!

the series to modifies

length

integer!

either the number of items to append (or retire, if it's negative and /cut is used), or, with /to, the total number of items

/to

-

the 'length is the total length (without /cut, doesn't do anything if the series is too long)

/cut

-

shortens the series if it's too long (with /to), or if length is negative (without /to)

/dup

-

duplicates values (repeats the existing values, but doesn't try to continue a sequence)

3. Examples

Empty series : appends none or null (0) values

>> extend [] 10
== [none none none none none none none none none none]

>> extend #{} 10
== #{00000000000000000000}

One element : builds an incrementing sequence

>> extend [1] 10
== [1 2 3 4 5 6 7 8 9 10 11]

>> extend/to "a" 26
== "abcdefghijklmnopqrstuvwxyz"

/dup disables the incrementation

>> extend/dup [1] 10
== [1 1 1 1 1 1 1 1 1 1 1]

Two elements or more : tries to continue the series

>> extend [0 5] 6
== [0 5 10 15 20 25 30 35]

>> extend [1 3 5] 3
== [1 3 5 7 9 11]

>> extend [1 5 3] 3 
== [1 5 3 1 5 3]

It works with date!, time!, char!, number!, and tuple! elements

>> extend/to reduce [now/date] 5
== [30-Jan-2013 31-Jan-2013 1-Feb-2013 2-Feb-2013 3-Feb-2013 ]

>> extend/to [08:00:00 08:30:00] 8  
== [8:00 8:30 9:00 9:30 10:00 10:30 11:00 11:30]

>> extend/to [0.0.0.127 64.0.1.127] 4 
== [0.0.0.127 64.0.1.127 128.0.2.127 192.0.3.127]

/cut is used to shorten the series

>> extend/cut [1 2 3 4 5 6] -1
== [1 2 3 4 5]

>> extend/cut/to [0 1 2 3 4 5 6] 3
== [0 1 2]

Non-numeric elements or mixed elements : repeats the values

>> extend ["cat" "rabbit" "dog"] 5
== ["cat" "rabbit" "dog" "cat" "rabbit" "dog" "cat" "rabbit"]

>> extend/to [5 dog 15] 8 
== [5 dog 15 5 dog 15 5 dog]
MakeDoc2 by REBOL- 31-Jan-2013