Peter Langfelder wrote:
>
> Sorry, I'm not sure what you want to do in points 2-4. Shrink the
> mountain vertically or horizontally? You can for example look up image
> resizing algorithms if you want to shrink the area under the mountain
> but keep the shape of the mountain (approximately) the
>> >> zCenter = mean(Z)
>> >
>> > How can that be right? Suppose your mountain is very flat, so that
>> > your mountain is effectively a cube. The Z values are all the same,
>> > and so their mean is the same. However the centre of mass is, by
>> > symmetry, clearly at height/2.
>> >
>> > Similar
> -Original Message-
> From: r-help-boun...@r-project.org [mailto:r-help-boun...@r-
> project.org] On Behalf Of Peter Langfelder
> Sent: Tuesday, November 09, 2010 3:49 PM
> To: Barry Rowlingson
> Cc: r-help@r-project.org; Ab Hu
> Subject: Re: [R] Centre of gravity
On Tue, Nov 9, 2010 at 3:40 PM, Barry Rowlingson
wrote:
> On Mon, Nov 8, 2010 at 5:15 PM, Peter Langfelder
> wrote:
>
>> If you also need the z coordinate, it simply the mean of the matrix Z.
>>
>> zCenter = mean(Z)
>
> How can that be right? Suppose your mountain is very flat, so that
> your mo
On Mon, Nov 8, 2010 at 5:15 PM, Peter Langfelder
wrote:
> If you also need the z coordinate, it simply the mean of the matrix Z.
>
> zCenter = mean(Z)
How can that be right? Suppose your mountain is very flat, so that
your mountain is effectively a cube. The Z values are all the same,
and so th
On Mon, Nov 8, 2010 at 11:31 PM, Ab Hu wrote:
>
> Thanks! Works great.
> I have more questions on this, so I'll continue here:
>
> Now that I have the weighted mean, is it possible to reduce the size of
> mountain based on this weighted mean such the original matrix remains 21x21
> while the mount
Thanks! Works great.
I have more questions on this, so I'll continue here:
Now that I have the weighted mean, is it possible to reduce the size of
mountain based on this weighted mean such the original matrix remains 21x21
while the mountain shrinks/converges.
Step for my analysis:
1) Find cent
Weighted mean of x and y coordinates (sorry for the pun :)), that is
something like
n = 21
y = matrix( c(1:n), n, n)
x = matrix( c(1:n), n, n, byrow = TRUE)
# These are the Center of mass coordinates:
xCenter = sum(x * Z)/sum(Z);
yCenter = sum(y * Z)/sum(Z);
If you also need the z coordinate, it
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