sort coordinates independently

Hi
I would like to know if there is a way to sort a group of vectors (x,y) according to y value, without separating them in different columns.
The problem is I have a vector in each cell, in a matrix m*n (with some missing values) which i would like to sort from the biggest value of y to the smallest, but always within a single row (or column, I can transpose them), independently.

Ex.
(x,y) (x1,y1) (x2,y2), (x3,y3)...
(x´,y´) (x´1, y´1) (x´2, y´2)....

And i would like to sort each row independently according to the value of the second coordenate

Thanks for your help!!