Re: Iterate through a list help
- To: mathgroup at smc.vnet.net
- Subject: [mg77259] Re: Iterate through a list help
- From: dh <dh at metrohm.ch>
- Date: Wed, 6 Jun 2007 07:00:55 -0400 (EDT)
- References: <f43gfu$2cq$1@smc.vnet.net>
Hi Nick,
by myList[[All,1]] you get all the first numbers.
hope this helps, Daniel
Nick wrote:
> Hello! I'm (somewhat) new to Mathematica and I need help to iterating
> through a list and counting the occurrence of a number.
>
> My list looks like:
>
> {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},{4,x+x^2},{4,1+x+x^2},{4,x
> +x^4},{4,1+x+x^4},
> {4,x^2+x^4},{4,1+x^2+x^4},{4,x^3+x^4},{4,1+x^3+x^4},{4,x+x^2+x^3+x^4},
> {4,1+x+x^2+x^3+x^4},
> {5,x+x^3},{5,1+x+x^3},{5,x^2+x^3},{5,1+x^2+x^3},{5,x+x^3+x^4},{5,1+x
> +x^3+x^4},{5,x^2+x^3+x^4},
> {5,1+x^2+x^3+x^4},{8,x},{8,x^2},{8,x^3},{8,x^4},{8,1+x},{8,1+x^2},
> {8,1+x^3},{8,x+x^2+x^3},{8,1+x+x^2+x^3},{8,1+x^4}}
>
> The number that I would need to keep track of is the first in each
> sub-
> list.
>
> So for the first couple {{1,0},{1,1},{2,x+x^2+x^4},{2,1+x+x^2+x^4},
> {4,x
> +x^2},........
>
> I would need to keep track of 1,1,2,2,4........
>
> It will not always be 1,2,4,5,8's. The numbers may be completely
> different on each pass. Each sublist may be composed of more items
> but the number that I need to keep track of will always be the 1st in
> the sub-list. Any help or suggestions that you can give me will be
> greatly appreciated. Thanks so much!
>
>