Ruby: collect, chr, join, sort

Given array of ASCII codes, return various sorted strings.

Screen capture of IDE display.

Define a function named sort_transform which receives an array of ASCII codes, e.g. [111, 112, 113, 114, 115, 113, 114, 110].

def sort_transform a

Assign given array a to new variable a1:

let a1 = a

Define a nested function named c which receives array a1, and returns a map. c() will be called four times in the return statement.

def c(a1)
  return [0,1,-2,-1].collect{ |x| a1[x].chr }.join('')
end

The array [0,1,-2,-1] passed to collect contains index values to map the first two and last two characters. The chr method converts each ASCII code to a character string.

The function sort_transform returns various strings of characters joined with hyphens, e.g. oprn-nors-sron-nors.

return [c(a1), c(a1.sort), c(a1.sort { |x,y| y <=> x }), c(a1.sort)].join('-')

In the return statement above, the array sort instruction c(a1.sort { |x,y| y <=> x }) uses the spaceship operator <=> to invert the sorting method from default ascending mode to descending mode, e.g. y <=> x.

Run the script

p(sort_transform([111, 112, 113, 114, 115, 113, 114, 110]), "oprn-nors-sron-nors")

The string returned should match.