R help - Nov 2017 - number to volume weighted distribution

Dear all

Strictly speaking it is not R question but as you are the most capable persons I
know I give it a try.

I am strugling with recalculation of number weighted to volume weighted
distribution.

Suppose I have objects (cubes) with size

x<- c(rep(10,20), rep(100, 10), rep(300,5))
I can get

plot(ecdf(x))

or the number weighted average

mean(x)
[1] 77.14286

or volume weighted average
weighted.mean(x, (x/sum(x^3)))
[1] 204.4444

However I am struggling with volume weighted ecdf.

Can you please give me some hints?

Cheers
Petr


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On 24/11/2017 6:27 AM, PIKAL Petr wrote:
> Dear all
> 
> Strictly speaking it is not R question but as you are the most capable
persons I know I give it a try.
> 
> I am strugling with recalculation of number weighted to volume weighted
distribution.
> 
> Suppose I have objects (cubes) with size
> 
> x<- c(rep(10,20), rep(100, 10), rep(300,5))
> I can get
> 
> plot(ecdf(x))
> 
> or the number weighted average
> 
> mean(x)
> [1] 77.14286
> 
> or volume weighted average
> weighted.mean(x, (x/sum(x^3)))
> [1] 204.4444
> 
> However I am struggling with volume weighted ecdf.
> 
> Can you please give me some hints?
I believe base R doesn't have a function for this, but Google says it 
exists in a couple of packages:  spatstat, Hmisc.  But you seem to be 
asking about a definition rather than a function:  it is obtained simply 
by normalizing the weights to sum to 1, then evaluating cumulative sums 
of them.

Duncan Murdoch

Hi Duncan

I tried Ecdf and/or wtd.quantile from Hmisc and it is working (probably).
Ecdf(x, q=.5)
Ecdf(x, weights=xw,col=2, add=T, q=.5)
wtd.quantile(x)
  0%  25%  50%  75% 100%
  10   10   10  100  300
wtd.quantile(x, weights=xw, type="i/n")
      0%      25%      50%      75%     100%
 10.0000 138.8667 192.5778 246.2889 300.0000

But could you please be more specific in this?
> But you seem to be asking about a
> definition rather than a function:  it is obtained simply by normalizing
the
> weights to sum to 1, then evaluating cumulative sums of them.
Actually, when I correctly calculate weights

xw <- (x^3)/sum(x^3)
sum(xw) equals to 1

but how can I plot ecdf with volume weighted data. Obviously

ecdf(x*xw) or ecdf(x^3*xw) is not correct.

Cheers
Petr
> -----Original Message-----
> From: Duncan Murdoch [mailto:murdoch.duncan at gmail.com]
> Sent: Friday, November 24, 2017 12:36 PM
> To: PIKAL Petr <petr.pikal at precheza.cz>; r-help at r-project.org
> Subject: Re: [R] number to volume weighted distribution
>
> On 24/11/2017 6:27 AM, PIKAL Petr wrote:
> > Dear all
> >
> > Strictly speaking it is not R question but as you are the most capable
persons I
> know I give it a try.
> >
> > I am strugling with recalculation of number weighted to volume
weighted
> distribution.
> >
> > Suppose I have objects (cubes) with size
> >
> > x<- c(rep(10,20), rep(100, 10), rep(300,5)) I can get
> >
> > plot(ecdf(x))
> >
> > or the number weighted average
> >
> > mean(x)
> > [1] 77.14286
> >
> > or volume weighted average
> > weighted.mean(x, (x/sum(x^3)))
> > [1] 204.4444
> >
> > However I am struggling with volume weighted ecdf.
> >
> > Can you please give me some hints?
>
> I believe base R doesn't have a function for this, but Google says it
exists in a
> couple of packages:  spatstat, Hmisc.  But you seem to be asking about a
> definition rather than a function:  it is obtained simply by normalizing
the
> weights to sum to 1, then evaluating cumulative sums of them.
>
> Duncan Murdoch
________________________________
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Nejste-li zam??len?m adres?tem tohoto emailu, nejste opr?vn?ni tento email
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zpo?d?n?m p?enosu e-mailu.

V p??pad?, ?e je tento e-mail sou??st? obchodn?ho jedn?n?:
- vyhrazuje si odes?latel pr?vo ukon?it kdykoliv jedn?n? o uzav?en? smlouvy, a
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- a obsahuje-li nab?dku, je adres?t opr?vn?n nab?dku bezodkladn? p?ijmout;
Odes?latel tohoto e-mailu (nab?dky) vylu?uje p?ijet? nab?dky ze strany p??jemce
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- trv? odes?latel na tom, ?e p??slu?n? smlouva je uzav?ena teprve v?slovn?m
dosa?en?m shody na v?ech jej?ch n?le?itostech.
- odes?latel tohoto emailu informuje, ?e nen? opr?vn?n uzav?rat za spole?nost
??dn? smlouvy s v?jimkou p??pad?, kdy k tomu byl p?semn? zmocn?n nebo p?semn?
pov??en a takov? pov??en? nebo pln? moc byly adres?tovi tohoto emailu p??padn?
osob?, kterou adres?t zastupuje, p?edlo?eny nebo jejich existence je adres?tovi
?i osob? j?m zastoupen? zn?m?.

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