Elffers/Method.md

## Method.md

      
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              Method.md
            
          
    ###Homework for 4 November 2013
####Array Method

delete_if

######Returns an array
Syntax: array.delete_if { | item | block }


Removes element from array if code block returns true.

Example 1: If you wish to remove all even numbers from an array:
my_array = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
my_array.delete_if {|number| number.even?} 

=> [1, 3, 5, 7, 9]
Example 2: If you wish to remove all names that are not capitalized:
names = ["Ada", "benjamin", "carl", "Dan", "Erastosthenes"]
names.delete_if { |name| name == name.downcase}

=> ["Ada", "Dan", "Erastosthenes"]

slice

######With one integer argument (index), returns value at that index.
######With two integer arguments(start, number_of_items), returns array with number_of_items elements starting at index (start)
######With one range argument (start_index..end_index), returns array of values from start index to end index, inclusive
#####Syntax:  array.slice(index)
array.slice(start, number_of_items)

array.slice(start_index..end_index)

Example:
    array = [1, 2, 3, 4, 5, 6, 7, 8, 9]
    array.slice(5)

=> 6
    array.slice(3, 5)

=> [4, 5, 6, 7, 8]
    array.slice(3..5)

=> [4, 5, 6]
Hash Method


select

#####Syntax: hash.select { block }

Returns a new array with keys and values for which the code block returns true.

Example 1: If you wish to return all months that inclue the letter "y":
months = {:jan => "january", :feb =>"february", :mar =>"march", :apr =>"april", :may ==> "may",
 :jun => "june", :jul => "july", :aug => "august", :sep => "september", :oct => "october", 
 :nov =>"november", :dec => "december"}

months.select {|key, value| value.include? "y"}

=> {:jan=>"january", :feb=>"february", :may=>"may", :jul=>"july"}
**Example 2: **
blah = {1 => [1, 2, 3], 2 => [4, 8], 3 =>[7, 8, 9], 4 => [35, 31]}
blah.select { |key, value| key == value.length }

=> {2=>[4, 8], 3=>[7, 8, 9]}

flatten

Syntax:  hash.flatten

hash.flatten(int) int = flattens number of times


Takes all keys and values and puts them into an array