re:sort pairs

*To*: mathgroup at yoda.physics.unc.edu*Subject*: re:sort pairs*From*: wmm at chem.wayne.edu (Martin McClain)*Date*: Mon, 15 Nov 93 10:55:13 EST

> How can I sort pairs of values -- basing the sort on the first value > and then break ties on the second value in the pair. > > Let's say I have n pairs on numbers in the following matrix > > data = { {x1,y1}, .....{xi, yi}, .....{xn,yn} } > > Using the Sort function in Mma, I can easily sort on the xi values, but > how can I do the secondary sort on the yi values?? I think this happens automatically. I just tried Sort[ {{5,9},{2,7},{5,6},{7,1},{5,2}}] with many permutations of the interior pairs, and the answer always comes out as {{2,7},{5,2},{5,6},{5,9},{7,1}}. Isn't this exactly what you want? Regards- Martin