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Re: Re: How to do count for sub list?????

  • To: mathgroup at smc.vnet.net
  • Subject: [mg82203] Re: [mg82160] Re: [mg82095] How to do count for sub list?????
  • From: DrMajorBob <drmajorbob at bigfoot.com>
  • Date: Sun, 14 Oct 2007 06:20:40 -0400 (EDT)
  • References: <200710120650.CAA04282@smc.vnet.net> <16695328.1192265948343.JavaMail.root@m35>
  • Reply-to: drmajorbob at bigfoot.com

If all the numbers are 0 or 1, you can Map Total:

list = {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0,
     0}, {0, 0, 0, 1, 0, 0, 0, 0, 0, 1}, {1, 0, 0, 0, 0, 0, 0, 0, 0,
     0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0,
     0}, {0, 0, 0, 0, 0, 0, 0, 0, 1, 0}, {0, 0, 0, 0, 1, 0, 0, 0, 0,
     0}};
Total /@ list

{0, 0, 2, 1, 0, 0, 1, 1}

The more general situation can be reduced to that using Unitize:

list = RandomInteger[{-1, 1}, {10, 10}]

{{-1, 0, 1, 1, 0, 0, 0, 0, -1, 1}, {0, 1, 0, 1, 1, -1, -1,
   0, -1, -1}, {-1, 0, 1, 0, 1, -1, -1, -1, 0, 0}, {1, 0, 0, 1, 0,
   0, -1, 1, 1, -1}, {0, 1, 0, 1, -1, -1, -1, 1, 0, 0}, {1, 1, 1, 0, 1,
    1, -1, 0, -1, 0}, {0, -1, 1, 0, 1, 1, -1, -1, 0, -1}, {1, 0, 1, 0,
   0, -1, 0, 1, -1, 1}, {-1, -1, 0, -1, -1, 0, 0, 1, 1, -1}, {0, -1, 1,
    0, 0, 1, -1, -1, 1, -1}}

Total /@ Unitize@list

{5, 7, 6, 6, 6, 7, 7, 6, 7, 7}

I suspect this is faster than using Count.

This counts non-zeroes by columns:

Total@Unitize@list

{6, 6, 6, 5, 6, 7, 7, 7, 7, 7}

Bobby

On Sat, 13 Oct 2007 02:59:38 -0500, Ricardo Samad <resamad at gmail.com>  
wrote:

> Hi,
>
> name your list:
>
> l = {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0,
>     0}, {0, 0, 0, 1, 0, 0, 0, 0, 0, 1}, {1, 0, 0, 0, 0, 0, 0, 0, 0,
>     0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0,
>     0}, {0, 0, 0, 0, 0, 0, 0, 0, 1, 0}, {0, 0, 0, 0, 1, 0, 0, 0, 0,
>     0}};
>
> and use
>
> Table[Length[l[[n]]] - Length[Position[l[[n]], 0]], {n, 1, Length[l]}]
>
> or
>
> Length[#] - Length[Position[#, 0]] & /@ l
>
>
> By the way, the result is {0, 0, 2, 1, 0, 0, 1, 1} and not  
> {0,0,1,1,0,0,1,1=
> }
> as written in your e-mail.
>
> Ricardo
>
>
>
>
> On 10/12/07, wangzhen0829 at gmail.com <wangzhen0829 at gmail.com> wrote:
>>
>> Hallo, everyone
>>
>> I am new to Mathematica, and now I have a problem with it, hope to get
>> some help from here.
>>
>> I have a
>>
>> {{0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {
>>   0, 0, 0, 1, 0, 0, 0, 0, 0, 1}, {1, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {
>>   0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, {
>>   0, 0, 0, 0, 0, 0, 0, 0, 1, 0}, {0, 0, 0, 0, 1, 0, 0, 0, 0, 0}}
>>
>>
>>
>> I need to get a list which represent the number of NON-zero number in
>> each sublist.
>>
>> I should get a list like:
>>
>> {0,0,1,1,0,0,1,1}
>>
>> Thank you!
>>
>>
>>
>
>
> --
> ____________________________________
> Ricardo Elgul Samad
>
> tel: (+55 11) 3133-9372
> fax: (+55 11) 3133-9374
>
> Centro de Lasers e Aplica=E7=F5es
> IPEN/CNEN-SP
> AV. Prof. Lineu Prestes 2242
> Cidade Universit=E1ria
> 05508-000
> S=E3o Paulo - SP
> Brazil
> ____________________________________
>
>
>



-- 

DrMajorBob at bigfoot.com


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