Hello,
I need to check if a word is in a list. I'm using hash because the
lists can be long (i'm under the impression hash is faster than array).
Basically I'm only interested that a key exists. I have to create
entries like:
So h["one"] gives true, and h["seven"] returns nil. But typing the
dummy value "true" is a waste of effort, and there's an ugliness in
there. Is there a better way to design a simple checklist?
So h["one"] gives true, and h["seven"] returns nil. But typing the
dummy value "true" is a waste of effort, and there's an ugliness in
there. Is there a better way to design a simple checklist?
irb(main):001:0> require 'set'
=> true
irb(main):002:0> s = Set.new %w{one two three four}
=> #<Set: {"three", "two", "one", "four"}>
irb(main):005:0> s.member? 'one'
=> true
irb(main):006:0> s.member? 'seven'
=> false
I need to check if a word is in a list. I'm using hash because the
lists can be long (i'm under the impression hash is faster than array).
Basically I'm only interested that a key exists. I have to create
entries like:
So h["one"] gives true, and h["seven"] returns nil. But typing the
dummy value "true" is a waste of effort, and there's an ugliness in
there. Is there a better way to design a simple checklist?
Use a set:
require 'set'
words = %w(one two three four five).to_set
words.include? 'one' # => true
words.include? 'seven' # => false
So h["one"] gives true, and h["seven"] returns nil. But typing the
dummy value "true" is a waste of effort, and there's an ugliness in
there. Is there a better way to design a simple checklist?
Thank you for your help
irb(main):001:0> a = %w{one two three four five}
=> ["one", "two", "three", "four", "five"]
irb(main):002:0> a.member? 'one'
=> true
irb(main):003:0> a.member? 'seven'
=> false
Hope that helps.
···
On 04/28/2005 07:48 AM, basi wrote:
--
Dr Balwinder Singh Dheeman Registered Linux User: #229709
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> Hello,
> I need to check if a word is in a list. I'm using hash because the
> lists can be long (i'm under the impression hash is faster than array).
A hash have to store "key" => value pairs, how will be more efficient
than an array? and why?
because Array lookups are O(n) and Hash lookups should be O(1). To
find something in an Array you have to traverse it completely and will
find the entry you are searching in expected n/2 steps. For hashes
there exist different implementations, but basically you compute the
possible position of an object from the object and just take a look if
it is there. (Oversimplified).
best regards,
Brian
···
On 28/04/05, Dr Balwinder S Dheeman <bsd.SANSPAM@cto.homelinux.net> wrote: