Re: I don't know how to ....

• Subject: [mg2460] Re: I don't know how to ....
• From: vince at vince.math.uconn.edu (Vince Giambalvo)
• Date: Mon, 13 Nov 1995 03:26:22 GMT
• Approved: usenet@wri.com
• Distribution: local
• Newsgroups: wri.mathgroup
• Organization: University of Connecticut
• Sender: daemon at wri.com ( )

```In article <47pm9c\$fbk at ralph.vnet.net> pehowland at taz.dra.hmg.gb (Paul E Howland) writes:

In article <471hgv\$gb3 at ralph.vnet.net>, bientin at cli.di.unipi.it (Paolo Bientinesi) writes:

|here's my problem:
|I need  a function that takea as input a list of pairs;
|the first element of every pair is a list, the second one is an integer;
|I want the function to calculate thhe
|biggest integer and to give as output the corresponding list.

Assuming your list is like:

data = {{{1,2,3},0}, {{4,5,6},5}, {{7,8,9},3}}

then the following will work:

In[1]:= Part[data, Position[
Map[#[[2]]&, data],
Max[Map[#[[2]]&, data]]
][[1,1]], 1]
Out[1]= {4, 5, 6}

Hope this helps,

I run in to lots of problems with solutions of this type, i.e, some
function of the input data is used more than once, in this case
Map[#[[2]]&,data].  I usually use a (temporary) variable to hold the
result, because I didn't think Mathematica would be smart enough to
save it and avoid recomputing. This usually involves setting up a
Module or Block, which also has overhead. Are there any guidelines for
doing this efficiently? Obviously the more complicated the function
the more expensive the recalculation, if it occurs.
Vince

```

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