RE: finding positions of elements in a list
- To: mathgroup at smc.vnet.net
- Subject: [mg86784] RE: [mg86761] finding positions of elements in a list
- From: "David Annetts" <davidannetts at aapt.net.au>
- Date: Thu, 20 Mar 2008 05:50:35 -0500 (EST)
- References: <200803200755.CAA29380@smc.vnet.net>
Hi Peter,
>
> mylist={{20, 109}, {20, 110}, {20, 111}, {21, 105}, {21,
> 106}, {21, 107},...}
>
> It's a list of {x,y} co-ordinates of some data points I'm analysing.
>
> I want to create a new list which contains only those data
> points whose y co-ordinate is greater than 80 ie. mylist[[n,2]]>80.
You can use Select. You want to select everything based on the second part
of every element in the list.
Given
mylist = {{20, 109}, {20, 110}, {20, 111}, {21, 105}, {21, 106},
{21, 107}};
The command
Select[mylist, #[[2]] > 109 &]
gets everything with a y-coordinate > 109.
Regards,
Dave.
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09:54
- References:
- finding positions of elements in a list
- From: PeterM <metaxas@lps.u-psud.fr>
- finding positions of elements in a list