how to get max and sum of 2nd column of array in ruby

Question

for an array like

s = [[1,2],[4,6],[2,7]]

How i can select max and sum of 2nd column in each row in one statement

max= 7
sum= 15

I know, that

sum = 0
max = 0
s.each{ |a,b| sum+=b;if max<b then max = b end }

would work.

Answer 1

The transpose method is nice for accessing "columns":

s = [[1,2],[4,6],[2,7]]
col = s.transpose[1]
p col.max #=> 7
p col.inject(:+) #=> 15

Answer 2

second_elements = s.map { |el| el[1] }
sum = second_elements.inject{|sum,x| sum + x }
max = second_elements.max

To be more clear: inject{|sum,x| sum + x } returns nil if array is empty, so if you want to get 0 for empty array then use inject(0, :+)