Phil Ter

It helps your life and without weighing too much on global warming

Sometimes it help you to filter some arrays

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This gem let you to filter any kind of arrays to get the item or attributes of selected items. It's short and dynamic which helps to increase the readability. Its trace is a usefull tool for teachers. Performance it's not its field, see the section below.

require 'philter'

# Simple arrays
[1,2,3].philter 1
=> [1]

[1,2,3].philter [2,3]
=> [2,3]

[1,2,3].philter '<= 2'
=> [1,2]

[1,2,3].philter '!= 2'
=> [1,3]

%w[red green blue].philter 'red'
=> ["red"]

%w[red green blue].philter %w(red blue)
=> ["red", "blue"]

# Array of hashes
[
{id: 1, name: 'Mark'    },
{id: 2, name: 'Larry'   }
].philter id: 1
=> [{:id=>1, :name=>"Mark"}]

[
{id: 1, name: 'Mark'    },
{id: 2, name: 'Larry'   },
{id: 3, name: 'Bill'    }
].philter id: [1,3]
=> [{:id=>1, :name=>"Mark"}, {:id=>3, :name=>"Bill"}]

[
{id: 1, name: 'Mark'    },
{id: 2, name: 'Larry'   },
{id: 3, name: 'Bill'    }
].philter id: '>2'
=> [{:id=>3, :name=>"Bill"}]

# Regular expression
[
{id: 1, name: 'Mark',   email: '[email protected]'  },
{id: 2, name: 'Larry',  email: '[email protected]'   },
{id: 3, name: 'Bill',   email: '[email protected]'    }
].philter email: /@gmail/
=> [{:id=>1, :name=>"Mark", :email=>"[email protected]"}, {:id=>2, :name=>"Larry",:email=>"[email protected]"}]

# Select attributes
[
{id: 1, name: 'Mark',   email: '[email protected]'  },
{id: 2, name: 'Larry',  email: '[email protected]'   },
{id: 3, name: 'Bill',   email: '[email protected]'    }
].philter({email: /@gmail/}, get: :name)
=> ["Mark", "Larry"]

Get the trace with the option debug: true

[
{id: 1, name: 'Mark'    },
{id: 2, name: 'Larry'   },
{id: 3, name: 'Bill'    }
].philter({id: [1,3]}, debug: true)
# You will get a trace
item Hash {:id=>1, :name=>"Mark"}
 a. search: Array [:id, [1, 3]]
  1.y label: Symbol .2 Hash[:id] == value | 1 == 1  => X
  1.y label: Symbol .2 Hash[:id] == value | 1 == 3
item Hash {:id=>2, :name=>"Larry"}
 a. search: Array [:id, [1, 3]]
  1.y label: Symbol .2 Hash[:id] == value | 2 == 1
  1.y label: Symbol .2 Hash[:id] == value | 2 == 3
item Hash {:id=>3, :name=>"Bill"}
 a. search: Array [:id, [1, 3]]
  1.y label: Symbol .2 Hash[:id] == value | 3 == 1
  1.y label: Symbol .2 Hash[:id] == value | 3 == 3  => X
------------------
 2 items found
=> [{:id=>1, :name=>"Mark"}, {:id=>3, :name=>"Bill"}]

Rails

Rails return relation objects that must be turned to array 

cities = City.all.to_a
  City Load (1.0ms)  SELECT "cities".* FROM "cities"
=> ... [cut]

cities.philter id: 1
=> [#<City id: 1, name: "Milano", code: "MI", region: "Lombardia", created_at: "2016-05-10 09:07:22", updated_at: "2016-05-10 09:07:22">]

cities.philter code: 'PA'
=> [#<City id: 4, name: "Palermo", code: "PA", region: "Sicilia", created_at: "2016-05-10 09:08:13", updated_at: "2016-05-10 09:08:13">]

cities.philter(region: /\Alomb/i).size
=> 4

Performance

If you need a lot of speed it would be better to use grep when you can or select manually your items.

require 'benchmark'

ar_test = 100.times.map{|n| n}
Benchmark.bmbm do |x|
  x.report("philter: ") { 1_000.times { ar_test.philter [1,2] } }
  x.report("grep: ")    { 1_000.times { ar_test.grep [1,2] } }
end

Rehearsal ---------------------------------------------
philter:    1.872000   0.000000   1.872000 (  1.859130)
grep:       0.031000   0.000000   0.031000 (  0.017170)
------------------------------------ total: 1.903000sec

                user     system      total        real
philter:    1.826000   0.000000   1.826000 (  1.834825)
grep:       0.016000   0.000000   0.016000 (  0.016777)

Benchmark.bmbm do |x|
  x.report("philter: ") { 1_000.times { ar_test.philter '< 50' } }
  x.report("select: ")  { 1_000.times { ar_test.select {|item| item < 50} } }
end

Rehearsal ---------------------------------------------
philter:    3.775000   0.000000   3.775000 (  3.779718)
select:     0.000000   0.000000   0.000000 (  0.004455)
------------------------------------ total: 3.775000sec

                user     system      total        real
philter:    3.744000   0.000000   3.744000 (  3.746851)
select:     0.016000   0.000000   0.016000 (  0.004338)

ar_test = [ {id: 1, name: 'Mark', email: '[email protected]'},
            {id: 2, name: 'Bill',  email: '[email protected]'},
            {id: 3, name: 'Larry', email: '[email protected]'}]
regexp = /\A.+gmail/
Benchmark.bmbm do |x|
  x.report("philter: ") { 10_000.times { ar_test.philter email: regexp } }
  x.report("select: ")  { 10_000.times { ar_test.select {|item| item[:email] =~ regexp} } }
end

Rehearsal ---------------------------------------------
philter:    0.515000   0.000000   0.515000 (  0.490562)
select:     0.000000   0.000000   0.000000 (  0.003961)
------------------------------------ total: 0.515000sec

                user     system      total        real
philter:    0.468000   0.000000   0.468000 (  0.473782)
select:     0.000000   0.000000   0.000000 (  0.003429)

Compatibility

Ruby 1.9+

Install

gem install philter

To use it in a rails project, add to gem file gem 'philter' and run bundle install

To Do

  • Add boolean operator to chain of conditions
  • Improve performance keeping the operations's trace

Contributing

  1. Fork it
  2. Create your feature branch (git checkout -b my-feature)
  3. Commit your changes (git commit -am 'I made extensive use of all my creativity')
  4. Push to the branch (git push origin my-feature)
  5. Create new Pull Request

Testing

bundle install

bundle exec ruby test\philter_test.rb

Found a bug?

Please open an issue.

License

The GNU Lesser General Public License, version 3.0 (LGPL-3.0) See LICENSE file