Re: Re: Re: Another question on lists

• To: mathgroup at smc.vnet.net
• Subject: [mg80731] Re: [mg80711] Re: [mg80641] Re: [mg80618] Another question on lists
• From: Carl Woll <carlw at wolfram.com>
• Date: Thu, 30 Aug 2007 02:36:31 -0400 (EDT)
• References: <27088617.1188205442155.JavaMail.root@m35> <200708280603.CAA14009@smc.vnet.net> <11155728.1188404471045.JavaMail.root@m35> <op.txt02ysvqu6oor@monster.gateway.2wire.net>

```DrMajorBob wrote:

> So the simplest method is
>
> Last@Sort@sample

Except that Sort[sample] is an O(n log n) operation, and
Ordering[sample, -1] is an O(n) operation.

Carl

>
> Bobby
>
> On Wed, 29 Aug 2007 03:24:08 -0500, Carl Woll <carlw at wolfram.com> wrote:
>
>> DrMajorBob wrote:
>>
>>> Here's an example:
>>>
>>> sample = Array[
>>>   RandomInteger[{1, 10}, {RandomInteger[{3, 10}]}] &, {15}]
>>> Length /@ %
>>>
>>> {{5, 7, 7, 1, 2, 5, 2, 7, 3}, {3, 4, 3, 8, 8}, {1, 4, 6, 6, 1, 6,
>>>   3}, {4, 6, 1, 9, 9, 7, 3, 5, 10}, {9, 1, 4, 2, 7, 1, 5}, {2, 8, 2,
>>>   4, 7, 3, 8}, {2, 10, 4, 7, 2, 10, 3}, {10, 5, 10, 6, 5, 10, 4, 3,
>>>   4}, {5, 2, 3, 10, 8}, {5, 1, 7}, {1, 5, 8, 4, 8, 5, 8, 2}, {3, 3, 8,
>>>    5, 1, 7}, {6, 10, 1, 6, 3, 5, 7, 6, 1, 7}, {3, 5, 1, 6, 6}, {10,
>>>   10, 9, 3, 9}}
>>>
>>> {9, 5, 7, 9, 7, 7, 7, 9, 5, 3, 8, 6, 10, 5, 5}
>>>
>>> Last@SortBy[sample, Length]
>>>
>>> {6, 10, 1, 6, 3, 5, 7, 6, 1, 7}
>>>
>>> or
>>>
>>> sample[[Ordering[sample, -1, Length[#1] < Length[#2] &]]]
>>>
>>> {{6, 10, 1, 6, 3, 5, 7, 6, 1, 7}}
>>>
>>>
>> Just a minor comment that the third argument of Ordering is not needed
>> in this case, since the default order used sorts by length of list
>> first. Try:
>>
>> sample[[Ordering[sample,-1]]]
>>
>>
>> Carl Woll
>> Wolfram Research
>>
>>> Bobby
>>>
>>> On Sun, 26 Aug 2007 22:20:22 -0500, Mauricio Esteban Cuak
>>> <cuak2000 at gmail.com> wrote:
>>>
>>>
>>>
>>>> Hello again.Thank you very much for your previous help. However, I
>>>> seem to stumble on another rock:
>>>>
>>>> I  have a list of n sub-lists with different number of elements. I
>>>> want to select the list with the highest number of elements.
>>>> I tried to combine the Select function with Lenght but couldn't do it:
>>>>
>>>> Select[list, Length /@ list >= Max[Length /@ list] &]
>>>>
>>>>
>>>> Regards,
>>>>
>>>> cd
>>>>
>>>> P.D.: Any tips,websites, books, on how to learn some basic programming
>>>> on Mathematica?
>>>> I'm slowly beginning to read "The Mathematica Book"...should I just
>>>> concentrate on that?
>>>>
>>>>
>>>>
>>>>
>>>
>>>
>>>
>>>
>>>
>>
>>
>>
>
>
>

```

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