CODEWITHSUNDEEP
ruby
Roberto da Silva
Roberto da Silva

Reputation: 43

How to enter data into a new array

Good morning people. I'm new to Rails and I'm using google translate to post here.

I have an array, and I would like to take a certain amount of values from the array, and put them in a new array1, for example, the first 7 numbers, and then the next 7 numbers in the second array:

array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40]
array2 = []    
array3 = []

array = [15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40]    
array2 = [1,2,3,4,5,6,7]   
array3 = [8,9,10,11,12,13,14]

How could I do this?

Upvotes: 0

Views: 103

Answers (3)

Cary Swoveland
Cary Swoveland

Reputation: 110665

Here are three ways to do that.

Use Array#slice!

array = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15,
         16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28,
         29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]

array2 = array.slice!(0,7)
  #=> [1, 2, 3, 4, 5, 6, 7]
array3 = array.slice!(0,7)
  #=> [8, 9, 10, 11, 12, 13, 14]

Now,

array
  #=> [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  #    28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]

If array is not to be mutated use Array#slice and add an additional variable (say, array1).

array2 = array.slice(0..6)
  #=> [1, 2, 3, 4, 5, 6, 7]
array3 = array.slice(7..13)
  #=> [8, 9, 10, 11, 12, 13, 14]
array1 = array.slice(14..)
  #=> [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  #    28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]

Use Enumerable#slice_before

i = 0
array2, array3, array = array.slice_before { [8, 15].include?(i += 1) }.to_a
  #=> [[1, 2, 3, 4, 5, 6, 7],
  #    [8, 9, 10, 11, 12, 13, 14],
  #    [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  #     28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]]

Now,

array2
  #=> [1, 2, 3, 4, 5, 6, 7]
array3
  #=> [8, 9, 10, 11, 12, 13, 14]
array
  #=> [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  #    28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]

If array is not to be mutated replace array with array1 on the left side of the equals sign.

Partition indices and use Array#values_at

array2, array3, array = [[*0..6], [*7..13], [*14..(array.size-1)]].
  map { |a| array.values_at(*a) }
  #=> [[1, 2, 3, 4, 5, 6, 7],
  #    [8, 9, 10, 11, 12, 13, 14],
  #    [15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27,
  #     28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40]]

If array is not to be mutated replace array with array1 on the left side of the equals sign.

Upvotes: 1

Josien
Josien

Reputation: 13867

You can use the Ruby shift Array method to accomplish this:

array = [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40]
array2 = array.shift(7) # array2 is now [1, 2, 3, 4, 5, 6, 7]
array3 = array.shift(7) # array3 is now [8, 9, 10, 11, 12, 13, 14]

Note that the shift method edits your original array as well.

By the way, this is pure Ruby (the programming language), no Rails (the framework) here! Hope this helps.

Upvotes: 4

Yurii Stefaniuk
Yurii Stefaniuk

Reputation: 1797

I think you need each_slice here:

res = array.each_slice(7).to_a

And you will get array with subarrays length 7 each. Last element will have remaining:

# outputs below
[
   [1, 2, 3, 4, 5, 6, 7],
   [8, 9, 10, 11, 12, 13, 14],
   [15, 16, 17, 18, 19, 20, 21],
   [22, 23, 24, 25, 26, 27, 28],
   [29, 30, 31, 32, 33, 34, 35],
   [36, 37, 38, 39, 40]
]

And then you can use each to go through elements

res.each { |subarray| # do with subarray what you need }

Or you can get any element you want by using these methods:

first_subarray = res.first
second_subarray = res.second
last_subarray = res.last

# or by index

third_subarray = res[2]

And key thing here that your initial array won't be reflected

Upvotes: 3

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