Ruby: Round number down to nearest number based on arbitrary list of numbers

arr = [0,5,7,8,11,16]puts arr.select{|item| item < 6}.max

Result:

This runs in linear time and doesn't require that the array is sorted.

ruby arrays rounding

If you are using relatively small arrays (and so not overly worried about efficiency), then this should work fine:

def down_to_array num, arr  arr.select{|y| y < num}.sort_by{|z| num-z }.firstend

E.g:

myarr = [0,5,7,8,11,16]puts down_to_array 6.5, myarr #=> 5

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