Ruby code hash of array based of a cutoff - arrays

Question

I have an array of floating numbers and a certain cutoff:
myData = [1.3,1.5,1.7,1.7,16.7,18.4,19.2,19.5,19.6,20.2,20.8,58.4,60.7,
61.2,61.2,116.4,121.2,122.7,123.2,123.2,138.5,149.5,149.5]
myBin = 5.3
I'd like to build a hash of arrays so that the difference by subtraction between the last element and the first element of the array is less or equal to myBin (5.3)
myHash = {
'hap_1' => [1.3,1.5,1.7],
'hap_2' => [16.8, 18.4,19.2,19.5,19.6,20.2,20.8],
'hap_3' => [58.4,60.7,61.2,61.2],
'hap_4' => [116.4,121.2],
'hap_5' => [122.7,123.2,123.2],
'hap_6' => [138.5],
'hap_7' => [149.5,149.5]}
Thank you so much in advance for your time and helpful assistance.
Cheers

Answer 1

Enumerable#slice_before can solve your problem:
first = myData[0]
myData.slice_before { |e| first = e if e - first > myBin }.to_a
#=> [[1.3, 1.5, 1.7, 1.7],
# [16.7, 18.4, 19.2, 19.5, 19.6, 20.2, 20.8],
# [58.4, 60.7, 61.2, 61.2],
# [116.4, 121.2],
# [122.7, 123.2, 123.2],
# [138.5],
# [149.5, 149.5]]

Answer 2

myData.drop(1).each_with_object([[myData.first]]) { |n,a|
n - a.last.first <= myBin ? (a.last << n) : a << [n] }.
each.with_index(1).with_object({}) { |(a,i),h| h["hap_#{i}"] = a }
#=> {"hap_1"=>[1.3, 1.5, 1.7, 1.7],
# "hap_2"=>[16.7, 18.4, 19.2, 19.5, 19.6, 20.2, 20.8],
# "hap_3"=>[58.4, 60.7, 61.2, 61.2],
# "hap_4"=>[116.4, 121.2],
# "hap_5"=>[122.7, 123.2, 123.2],
# "hap_6"=>[138.5],
# "hap_7"=>[149.5, 149.5]}

Answer 3

You could build a customer enumerator that works like chunk_while, but compares each chunk's first element to the current one, i.e. 1.3 to 1.5, then 1.3 to 1.7 and so on:
module Enumerable
def chunk_while1
return enum_for(__method__) unless block_given?
each_with_object([]) do |elt, result|
if result.last && yield(result.last.first, elt)
result.last << elt
else
result << [elt]
end
end
end
end
Usage:
data = [
1.3, 1.5, 1.7, 1.7, 16.7, 18.4, 19.2, 19.5, 19.6, 20.2, 20.8, 58.4, 60.7,
61.2, 61.2, 116.4, 121.2, 122.7, 123.2, 123.2, 138.5, 149.5, 149.5
]
result = data.chunk_while1 { |i, j| j - i <= 5.3 }
#=> [
# [1.3, 1.5, 1.7, 1.7],
# [16.7, 18.4, 19.2, 19.5, 19.6, 20.2, 20.8],
# [58.4, 60.7, 61.2, 61.2],
# [116.4, 121.2],
# [122.7, 123.2, 123.2],
# [138.5],
# [149.5, 149.5]
# ]
The result can then be converted to a hash, e.g. via:
result.map.with_index(1) { |a, i| ["hap_#{i}", a] }.to_h
#=> {
# "hap_1"=>[1.3, 1.5, 1.7, 1.7],
# "hap_2"=>[16.7, 18.4, 19.2, 19.5, 19.6, 20.2, 20.8],
# "hap_3"=>[58.4, 60.7, 61.2, 61.2],
# "hap_4"=>[116.4, 121.2],
# "hap_5"=>[122.7, 123.2, 123.2],
# "hap_6"=>[138.5],
# "hap_7"=>[149.5, 149.5]
# }