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New page: Ruby Ranges allow data to be represented in the form of a range (in other words a data set with start and end values and a logical sequence of values in between). The values in a range can...
Ruby Ranges allow data to be represented in the form of a range (in other words a data set with start and end values and a logical sequence of values in between). The values in a range can be numbers, characters, strings or objects. In the chapter we will look at the three types of range supported by Ruby, sequences, conditions and intervals.
== Ruby Sequence Ranges ==
Sequence ranges in Ruby are used to create a range of successive values - consisting of a start value, an end value and a range of values in between.
Two operators are available for creating such ranges, the inclusive two-dot (..) operator and the exclusive three-dot operator (...). The inclusive operator includes both the begin and end values in the range. The exclusive range operator excludes the end value from the sequence. For example:
<pre>
1..10 # Creates a range from 1 to 10 inclusive
1...10 # Creates a range from 1 to 9
</pre>
A range may be converted to a list using the Ruby ''to_a'' method. For example:
<pre>
(1..10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
(1...10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
</pre>
As mentioned previously, ranges are not restricted to numerical values. We can also create a character based range:
<pre>
('a'..'l').to_a
=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"]
</pre>
Also, we can create range based on string values:
<pre>
('cab'..'car').to_a
=> ["cab", "cac", "cad", "cae", "caf", "cag", "cah", "cai", "caj", "cak", "cal", "cam", "can", "cao", "cap", "caq", "car"]
</pre>
Range values may also be objects. The only requirements for placing an object in a range is that the object provides a mechanism for returning the next object in the sequence via ''succ'' and it must be possible to compare the objects using the <=> operator.
== Using Range Methods ==
Given the object-oriented nature of Ruby it should come as no surprise to you that a range is actually an object. As such, there are a number of methods of the Range class which can be accessed interrogate and manipulate a range object.
<pre>
words = 'cab'..'car'
words.min # get lowest value in range
=> "cab"
words.max # get highest value in range
=> "car"
words.include?('can') # check to see if a value exists in the range
=> true
words.reject {|subrange| subrange < 'cal'} # reject values below a specified range value
=> ["cal", "cam", "can", "cao", "cap", "caq", "car"]
</pre>
== Ruby Sequence Ranges ==
Sequence ranges in Ruby are used to create a range of successive values - consisting of a start value, an end value and a range of values in between.
Two operators are available for creating such ranges, the inclusive two-dot (..) operator and the exclusive three-dot operator (...). The inclusive operator includes both the begin and end values in the range. The exclusive range operator excludes the end value from the sequence. For example:
<pre>
1..10 # Creates a range from 1 to 10 inclusive
1...10 # Creates a range from 1 to 9
</pre>
A range may be converted to a list using the Ruby ''to_a'' method. For example:
<pre>
(1..10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
(1...10).to_a
=> [1, 2, 3, 4, 5, 6, 7, 8, 9]
</pre>
As mentioned previously, ranges are not restricted to numerical values. We can also create a character based range:
<pre>
('a'..'l').to_a
=> ["a", "b", "c", "d", "e", "f", "g", "h", "i", "j", "k", "l"]
</pre>
Also, we can create range based on string values:
<pre>
('cab'..'car').to_a
=> ["cab", "cac", "cad", "cae", "caf", "cag", "cah", "cai", "caj", "cak", "cal", "cam", "can", "cao", "cap", "caq", "car"]
</pre>
Range values may also be objects. The only requirements for placing an object in a range is that the object provides a mechanism for returning the next object in the sequence via ''succ'' and it must be possible to compare the objects using the <=> operator.
== Using Range Methods ==
Given the object-oriented nature of Ruby it should come as no surprise to you that a range is actually an object. As such, there are a number of methods of the Range class which can be accessed interrogate and manipulate a range object.
<pre>
words = 'cab'..'car'
words.min # get lowest value in range
=> "cab"
words.max # get highest value in range
=> "car"
words.include?('can') # check to see if a value exists in the range
=> true
words.reject {|subrange| subrange < 'cal'} # reject values below a specified range value
=> ["cal", "cam", "can", "cao", "cap", "caq", "car"]
</pre>
