[ACCEPTED]-Ruby: How to find the index of the minimum array element?-minimum
Accepted answer
I believe this will traverse the array only 1 once and is still easy to read:
ary = [2,3,4,5,1] # => [2,3,4,5,1]
ary.each_with_index.min # => [1, 4]
# where 1 is the element and 4 is the index
This traverses the array only once whereas 1 ary.index(ary.min) would traverse it twice:
ary.each_with_index.inject(0){ |minidx, (v,i)| v < a[minidx] ? i : minidx }
It would be interesting to read about other 2 situations (finding all and only last minimal 1 element).
ary = [1, 2, 1]
# find all matching elements' indexes
ary.each.with_index.find_all{ |a,i| a == ary.min }.map{ |a,b| b } # => [0, 2]
ary.each.with_index.map{ |a, i| (a == ary.min) ? i : nil }.compact # => [0, 2]
# find last matching element's index
ary.rindex(ary.min) # => 2
I actually like @andersonvom 's answer, it 3 only need to loop the array once and still 2 get the index.
And in case you don't want 1 to use ary.each_with_index.min, here is what you can do:
ary = [2,3,4,5,1] # => [2,3,4,5,1]
_, index_of_minimal_value_in_array = ary.each_with_index.min # => [1, 4]
index_of_minimal_value_in_array # => 4
Source:
stackoverflow.com
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