How to count the number of arrays in a nested array

Question

I want to count the number of arrays in the nested arrays of an array

array = [[["-", 0, "I"], ["+", 0, "you"]], [["+", 3, "i"]], [["-", 4, "loved"], ["-", 5, "that"], ["+", 5, "it"], ["+", 6, "tasted"], ["+", 7, "like"]]]

This example would have 8 nested arrays inside the arrays in the array array. (not sure if I worded that right)

What do you want here? 8? You could use Regular Expression for that. I think it's the simplest way — Desorder
– Desorder, Commented Mar 10, 2016 at 1:05
array.first.count should do? @Desorder - could you explain how you would use RegularExpressions here? — BroiSatse
– BroiSatse, Commented Mar 10, 2016 at 1:06
@BroiSatse array.first.count and array.first.size gives 2. — Rob
– Rob, Commented Mar 10, 2016 at 1:10
Ah, there are two arrays, hard to spot those brackets. array.flatten(1).count will do. — BroiSatse
– BroiSatse, Commented Mar 10, 2016 at 1:11
@Desorder - Regex can be used for strings, how do you want to apply regex pattern to an array? Convert it to string first? — BroiSatse
– BroiSatse, Commented Mar 10, 2016 at 1:16

BroiSatse · Accepted Answer · 2016-03-10 01:24:58Z

6

The easiest/cleanest way is to partially flatten an array by one nesting level:

array.flatten(1).count

Other option is to sum sub-arrays:

array.inject([], :+).count

However the real question you need to ask to yourself is - how did I end up with such a weird construct?

answered Mar 10, 2016 at 1:24

BroiSatse

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Sebastián Palma · Accepted Answer · 2017-07-30 17:53:50Z

0

The key here is to properly state the question - I assume it to be count the number of arrays inside the nested array, which themselves do not contain another arrays.

def count_inner_arrays(arr)
  sub_arrays = arr.select { |el| el.is_a? Array }
  sub_arrays.empty? ? 1 : sub_arrays.map(&method(:count_inner_arrays)).inject(0, :+)
end

edited Jul 30, 2017 at 17:53

Sebastián Palma

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answered Mar 10, 2016 at 1:15

Cthulhu

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