Re: Ordering function weird?

*To*: mathgroup at smc.vnet.net*Subject*: [mg82673] Re: [mg82645] Ordering function weird?*From*: DrMajorBob <drmajorbob at bigfoot.com>*Date*: Sun, 28 Oct 2007 03:59:32 -0500 (EST)*References*: <14809680.1193491087839.JavaMail.root@m35>*Reply-to*: drmajorbob at bigfoot.com

Ordering works exactly the same way on both x and y; I have no idea what you think is different. y = {1, 2, 7, 8, 9, 1, 2} Ordering@y y[[Ordering@y]] Sort@y {1, 2, 7, 8, 9, 1, 2} {1, 6, 2, 7, 3, 4, 5} {1, 1, 2, 2, 7, 8, 9} {1, 1, 2, 2, 7, 8, 9} Ordering@y gives the positions, in y, of the elements of Sort@y. The first element of Sort@y (1) is the first element of y, the second element of Sort@y (also 1) is the 6th element of y, the third element of Sort@y (2) is the 2nd element of y, the fourth element of Sort@y (2 again) is the 7th element of y, and so on. Bobby On Sat, 27 Oct 2007 04:59:25 -0500, Claus <claus.haslauer at web.de> wrote: > Hi, > say I've got two sets of number, x and y, which I want to rank. See the > example below. I totally expect and want the result of Ordering[x]. But > I neiter understand nor expect the result of Ordering[y]. Both Sort[x] > and Sort[y] are ok. > Can anybody explain to me Ordering[y]? > Thanks, > Claus > > > In[3]:= x = {1, 2, 3, 6, 10, 3, 4} > y = {1, 2, 7, 8, 9, 1, 2} > > Out[3]= {1, 2, 3, 6, 10, 3, 4} > > Out[4]= {1, 2, 7, 8, 9, 1, 2} > > In[5]:= Sort[x] > Sort[y] > > Out[5]= {1, 2, 3, 3, 4, 6, 10} > > Out[6]= {1, 1, 2, 2, 7, 8, 9} > > In[7]:= Ordering[x] > Ordering[y] > > Out[7]= {1, 2, 3, 6, 7, 4, 5} > > Out[8]= {1, 6, 2, 7, 3, 4, 5} > > -- DrMajorBob at bigfoot.com