Re: Iterate through a list

• To: mathgroup at smc.vnet.net
• Subject: [mg76962] Re: Iterate through a list
• From: dh <dh at metrohm.ch>
• Date: Thu, 31 May 2007 03:12:06 -0400 (EDT)
• References: <f3gqtq\$42r\$1@smc.vnet.net>

```
Hi Nick,

Try Part:

yourList[[All,1]]

hope this helps, Daniel

Nick Hoffman 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!

>

```

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