R help - Sep 2012 - How does "apply.monthly" function works (xts package)

Hi everybody.

I use to work with monthly data, however this is my first time working with
weekly data.

I have 4 data bases with monthly data and 1 with weekly data, so I want to
convert my weekly to monthly data in order to have the same periodicity in
all of them.

I've read that package xts can help me with this issue, so I have done the
following script:

*ini_week<-as.Date("2010-09-19")

final_week<-seq(ini_week, length.out=104, by = "1 week")

vts<-read.csv("C:/DATA.csv",header = TRUE)
vts<-vts[,2]

wvts<-xts(vts, order.by=final_week)
mes<-apply.monthly(wvts,sum)

*A portion of the result is this one:

           [,1]
2010-09-26  2.9
2010-10-31  8.5
2010-11-28  5.8
2010-12-26  5.5
2011-01-30  7.5
....

It seem to be quite well however I have still the question about how does
it work...I mean, for example the last week of September 2010 goes from *
"2010-09-26"* to *"2010-10-03"* with a total number of sales
of that week
of 1.5 USD millions...so, how does R assign the portion of those 1.5 USD
millions to the last days of September and the first 2 days of October?

Thanks a lot in advance.

Regards.

	[[alternative HTML version deleted]]

On Thu, Sep 27, 2012 at 4:03 AM, CALEF ALEJANDRO RODRIGUEZ CUEVAS
<alejandro.rodriguez.cuevas at gmail.com> wrote:
> Hi everybody.
>
> I use to work with monthly data, however this is my first time working with
> weekly data.
>
> I have 4 data bases with monthly data and 1 with weekly data, so I want to
> convert my weekly to monthly data in order to have the same periodicity in
> all of them.
>
> I've read that package xts can help me with this issue, so I have done
the
> following script:
>
> *ini_week<-as.Date("2010-09-19")
>
> final_week<-seq(ini_week, length.out=104, by = "1 week")
>
> vts<-read.csv("C:/DATA.csv",header = TRUE)
> vts<-vts[,2]
>
> wvts<-xts(vts, order.by=final_week)
> mes<-apply.monthly(wvts,sum)
>
> *A portion of the result is this one:
>
>            [,1]
> 2010-09-26  2.9
> 2010-10-31  8.5
> 2010-11-28  5.8
> 2010-12-26  5.5
> 2011-01-30  7.5
> ....
>
> It seem to be quite well however I have still the question about how does
> it work...I mean, for example the last week of September 2010 goes from *
> "2010-09-26"* to *"2010-10-03"* with a total number of
sales of that week
> of 1.5 USD millions...so, how does R assign the portion of those 1.5 USD
> millions to the last days of September and the first 2 days of October?
It doesn't. The vector is divided into non-overlapping intervals by
the endpoints() function and they are summed separately. Read through
?endpoints

Michael
>
> Thanks a lot in advance.
>
> Regards.
>
>         [[alternative HTML version deleted]]
>
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