如何使用 ruby 对嵌套的坐标数组进行排序

Question

I am trying to sort with ruby a nested array like this:

[[810, 266], [236, 236], [814, 820], [230, 800]]

Each array [x, y] means a position in a photo and I want to sort it so the first array in the nested array is the one in the top left, the second in the top right, the third in the bottom left and the last in the bottom right. The array will always be 4 arrays into one [[x,y],[x,y],[x,y],[x,y]] .

input

[[810, 266], [236, 236], [814, 820], [230, 800]]

output

[[236, 236], [810, 266], [230, 800], [814, 820]]

Answer 1

You can use sort_by to sort by y first (top to bottom) and x second (left to right):

ary = [[810, 266], [236, 236], [814, 820], [230, 800]]

ary.sort_by { |x, y| [y, x] }
#=> [[236, 236], [810, 266], [230, 800], [814, 820]]

This works, because arrays are sorted in an element-wise manner, see Array#<=> .