String comparison
- To: mathgroup at smc.vnet.net
- Subject: [mg55009] String comparison
- From: yasdfer at yahoo.com
- Date: Wed, 9 Mar 2005 06:34:34 -0500 (EST)
- Sender: owner-wri-mathgroup at wolfram.com
Hi,
I want to sort a list/table based on an arbitrary "column".
In[1]:= alist = {{a, 3, "bca"}, {b, 1, "cba"}, {c, 2, "abc"}};
If I want to sort based on say the second column, I can use:
In[2]:= Sort[alist, #1[[2]] > #2[[2]] &]
Out[2]:= {{a, 3, bca}, {c, 2, abc}, {b, 1, cba}}
With the string column however, the method fails:
In[3]:= Sort[alist, #1[[3]] > #2[[3]] &]
Out[3]:= {{a, 3, bca}, {b, 1, cba}, {c, 2, abc}}
I can get away with,
In[4]:= Reverse[RotateRight[#, 2] & /@ Sort[RotateLeft[#, 2] & /@
alist]]
Out[4]:= {{b, 1, cba}, {a, 3, bca}, {c, 2, abc}}
Question is, what function can I pass to Sort[] directly to avoid the
bending and twisting?
In general, how does one compare strings for lexical ordering? Noticed
that, Greater["a", "b"] does not evaluate either.
Thanks.