Re: Delete close, but not identical elements in an array
- To: mathgroup at smc.vnet.net
- Subject: [mg123369] Re: Delete close, but not identical elements in an array
- From: A Retey <awnl at gmx-topmail.de>
- Date: Sun, 4 Dec 2011 02:51:02 -0500 (EST)
- Delivered-to: l-mathgroup@mail-archive0.wolfram.com
- References: <jbcsev$bvn$1@smc.vnet.net>
Am 03.12.2011 11:08, schrieb Peter Rodenbach:
> Hi,
>
> I have the problem that I have to indentify peaks in an 2D array. I
> can do this by Ordering[] the entries in the Flatten[] list. Then I
> indentify the positions of the peaks in the array and write them into
> a list. An example I work on in an 512 x 512 Pixel array:
>
> Peaks={{229,170},{119,265},{331,202},{118,264},{314,245}}
>
> As you can see from those 5 peaks, Number 2 and 4 belong to the same
> peak. As I have to count the data at that positions and compare them,
> I have to get rid of the peak postions that neighbor each other, as
> they actually belong to the same peak.
>
> What I want now is: have Mathem. evaluate the positions in the list
> and delete those which are +-10 pixels around any other.
> So the list would look like Peaks={{229,170},{119,265},{331,202},
> {314,245}} afterwards.
maybe this is even "better" than just deleting close values, depending
on what you actually do:
Mean /@ Gather[peaks, Norm[#1 - #2] <= 10 &]
hth,
albert