Well, if I understand your query, wouldn't the following simple approach
suffice -- it assumes that the results for each company are ordered by
year, as your example seems to show:
## test is your example data
## first remove NA's
test2 <- na.omit(test)
## Now just use tapply():
> out <-with(test2, tapply(CLOSE_SHARE_PRICE, COMPANY_NUMBER,
+ FUN =function(x)100 /x[1]))
> out
1091347 11356069 22705 SC192761
12.28501 91.74312 15.26718 91.74312
## essentially a labelled vector
##You can use %/% if you only want the whole number of shares that can be
purchased
It's somewhat messier if the results are not ordered by date within company
-- you could use by() and POSIXct to order the dates within company to get
the right one.
Cheers,
Bert Gunter
"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Tue, Apr 13, 2021 at 11:34 AM e-mail ma015k3113 via R-help <
r-help@r-project.org> wrote:
> Rui, excellent diagnosis and suggestion. It worked but my damn logic is
> still not delivering what I want-will spend more time on it tomorrow.
>
>
> Kind regards
>
> Ahson
>
> > On 13 April 2021 at 17:06 Rui Barradas <ruipbarra...@sapo.pt> wrote:
> >
> >
> > Hello,
> >
> > A close parenthesis is missing in the nd if.
> >
> >
> > for (i in 1:(nrow(PLC_Return)-1)){
> > if (i == 1){
> > NUMBER_OF_SHARES[i] = 100/is.na(CLOSE_SHARE_PRICE[i])
> > } else if(is.na(PLC_Return[i, 1]) == is.na(PLC_Return[i + 1, 1])){
> > NUMBER_OF_SHARES[i]=0
> > } else {
> > NUMBER_OF_SHARES[i] = 100/is.na(CLOSE_SHARE_PRICE[i])
> > }
> > }
> >
> >
> > Hope this helps,
> >
> > Rui Barradas
> >
> > Às 13:51 de 13/04/21, e-mail ma015k3113 via R-help escreveu:
> > > Dear All,I have a dataframe with 4 variables and I am trying to
> calculate how many shares can be purchased with £100 in the first year when
> the company was listed
> > >
> > > The data looks like:
> > >
> > > COMPANY_NUMBER YEAR_END_DATE CLOSE_SHARE_PRICE NUMBER_OF_SHARES
> > > 22705 30/09/2002
> NA 0
> > > 22705 30/09/2004
> NA 0
> > > 22705 30/09/2005
> 6.55 0
> > > 22705 30/09/2006
> 7.5 0
> > > 22705 30/09/2007
> 9.65 0
> > > 22705 30/09/2008
> 6.55 0
> > > 1091347 31/01/2010
> 8.14 0
> > > 1091347 31/01/2011
> 11.38 0
> > > 11356069 30/06/2019
> 1.09 0
> > > SC192761 31/01/2000
> NA 0
> > > SC192761 31/01/2001
> NA 0
> > > SC192761 31/01/2002
> NA 0
> > > SC192761 31/01/2004
> NA 0
> > > SC192761 31/01/2005
> NA 0
> > > SC192761 31/01/2006
> 1.09 0
> > > SC192761 31/01/2008
> 1.24 0
> > > SC192761 31/01/2009
> 0.9 0
> > > SC192761 31/01/2010 1.14
> 0
> > > SC192761 31/01/2011 1.25
> 0
> > > SC192761 31/01/2012 1.29
> 0
> > >
> > >
> > > The code I have written is
> > >
> > > i <- 0
> > >
> > > for (i in 1:(nrow(PLC_Return)-1))
> > > if (i == 1)
> > > {
> > > NUMBER_OF_SHARES[i] = 100/is.na(CLOSE_SHARE_PRICE[i])
> > > } else if
> > > (is.na(PLC_Return[i, 1]) == is.na(PLC_Return[i + 1, 1])
> > > {
> > > NUMBER_OF_SHARES[i]=0
> > > } else
> > > {
> > > NUMBER_OF_SHARES[i] = 100/is.na(CLOSE_SHARE_PRICE[i])
> > > }
> > >
> > >
> > > The error I get is Error: unexpected 'else' in:
> > >
> > > " NUMBER_OF_SHARES[i] = 0
> > > } else"
> > >> {NUMBER_OF_SHARES[i] = 100/is.na(CLOSE_SHARE_PRICE[i])}
> > >>
> > >> }
> > > Error: unexpected '}' in "}"
> > >
> > >
> > > Don't know how to fix it-any help will be appreciated.
> > >
> > >
> > > Kind regards
> > >
> > >
> > > Ahson
> > > [[alternative HTML version deleted]]
> > >
> > > ______________________________________________
> > > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > > https://stat.ethz.ch/mailman/listinfo/r-help
> > > PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> > > and provide commented, minimal, self-contained, reproducible code.
> > >
>
> ______________________________________________
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
[[alternative HTML version deleted]]
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