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  • each, collect and map in ruby

    @taranjeet.singh
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    1> 'each' will loop through each element of the array and evaluate whatever is return inside the block, but it returns the original array without any change.

    1. a = [5,10,15,20]
    2.  => [5, 10, 15, 20] 
    3. a.each {|t| t+2}
    4.  => [5, 10, 15, 20] 
    5. a.each {|t| puts(t+2)}
    6. 7
    7. 12
    8. 17
    9. 22
    10.  => [5, 10, 15, 20]

    (Thus we see that whatever is written inside the each block is evaluated and the original array is returned at the end)


    2>'collect' returns the new array which is created as the result of executing the specified block for every item of the given array.

    1. a = [1,2,3,4]
    2.  
    3. a.object_id
    4.  => 76272700
    5.  
    6. a.collect {|x| x*3}
    7. => [3, 6, 9, 12]
    8.  
    9. a.object_id
    10. =>76337640
    11.  
    12. puts a
    13.  => [1, 2, 3, 4]

    (Thus we can see collect returns a new array after performing the operations defined in the block on each element of original array, leaving the original array intact)

    3> 'map' is similar to 'collect'. There is no specific difference between them in functionality, both of them perform the same thing

    1. c = [1,2,3,4]
    2.  => [1, 2, 3, 4] 
    3. c.object_d
    4.  => 76350610 
    5.  
    6. c.map {|x| x*5}
    7.  => [5, 10, 15, 20] 
    8.  
    9. p c.object_id
    10.  => 76350610 
    11.  
    12. p c
    13. => [1, 2, 3, 4]

    (Thus we can see map also returns a new array after performing the operations defined in the block on each element of original array, leaving the original array intact)

    each collect map Ruby RAILS array iterate
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