# [R] [EXT] Calculating the total change in shareprice over a time periond

David K Stevens d@v|d@@teven@ @end|ng |rom u@u@edu
Wed Mar 31 20:17:54 CEST 2021

```Mr. Blueyonder,

There are a number of problems with this.

1) is the data below really in a data frame? I coerced your table into a
data frame, guessing at the structure and when I print out the 1st three
rows I get an alignment into proper columns

COMPANY_NUMBER COMPANY_NAME                CITY YEAR_END_DATE
CLOSE_SHARE_PRICE
1           22705  CARDIFF PROPERTY PUBLIC LIMITED COMPANY
(THE)Egham    30/09/2005                NA
2           22705  CARDIFF PROPERTY PUBLIC LIMITED COMPANY
(THE)Egham    30/09/2006                NA
3           22705  CARDIFF PROPERTY PUBLIC LIMITED COMPANY
(THE)Egham    30/09/2007              9.65

I'd guess that your PLC is actually a 1 column data frame based on how
you present it. Because what you gave is so small, I just added commas
where they seemed suitable and used

to create the data frame above. It's likely that your actual problem is
much larger so I'd export the data as a CSV file, and read it into R in
a similar way using

2) Your code is incorrect as is for two reasons. a) for your approach to
work, you'll need to create an empty column CH_SH_PRICE before running
the loop, because your loop is trying to place data into a non-existent
column b) the code PLC\$CH_SH_PRICE(i+1) has to use square brackets,
otherwise R thinks PCL\$CH_SH_PRICE is a function rather than a reference
to column element i+1 as in PLC\$CH_SH_PRICE[i+1]

Also, the functionisTRUE is actually the following

function (x)
is.logical(x) && length(x) == 1L && !is.na(x) && x

Is this really what you want to do, rather than just checking the
company number, as inPLC[i,1] == PLC[i+1,1]?

Assuming (tentatively) I guessed right, here's what I got

COMPANY_NUMBER                            COMPANY_NAME CITY
YEAR_END_DATE CLOSE_SHARE_PRICE CH_SH_PRICE
1          22705 CARDIFF PROPERTY PUBLIC LIMITED COMPANY (THE)Egham
30/09/2005                NA          NA
2          22705 CARDIFF PROPERTY PUBLIC LIMITED COMPANY (THE)Egham
30/09/2006                NA          NA
3          22705 CARDIFF PROPERTY PUBLIC LIMITED COMPANY (THE)Egham
30/09/2007              9.65          NA
4          22705 CARDIFF PROPERTY PUBLIC LIMITED COMPANY (THE)Egham
30/09/2008              6.55       -3.10

Good luck.

David Stevens

On 3/31/2021 11:04 AM, e-mail ma015k3113 via R-help wrote:
> Dear All, I have a data frame which is structured as follows:
>
>
> COMPANY_NUMBER  COMPANY_NAME    CITY    YEAR_END_DATE   CLOSE_SHARE_PRICE
> 22705   CARDIFF PROPERTY PUBLIC LIMITED COMPANY         (THE)Egham      30/09/2005      NA
> 22705   CARDIFF PROPERTY PUBLIC LIMITED COMPANY         (THE)Egham      30/09/2006      NA
> 22705   CARDIFF PROPERTY PUBLIC LIMITED COMPANY         (THE)Egham      30/09/2007      9.65
> 22705   CARDIFF PROPERTY PUBLIC LIMITED COMPANY         (THE)Egham      30/09/2008      6.55
> 22705   CARDIFF PROPERTY PUBLIC LIMITED COMPANY         (THE)Egham      30/09/2009      6.55
> 22705   CARDIFF PROPERTY PUBLIC LIMITED COMPANY         (THE)Egham      30/09/2010      7.5
> 10395804        TOC PROPERTY BACKED LENDING TRUST PLC   Newcastle Upon Tyne     30/11/2016      NA
> 10395804        TOC PROPERTY BACKED LENDING TRUST PLC   Newcastle Upon Tyne     30/11/2017      1.04
> 10395804        TOC PROPERTY BACKED LENDING TRUST PLC   Newcastle Upon Tyne     30/11/2018      1.04
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2000      NA
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2001      NA
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2003      NA
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2004      NA
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2005      NA
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2006      1.09
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2007      1.17
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2008      1.24
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2009      0.9
> SC192761        MARTIN CURRIE GLOBAL PORTFOLIO TRUST PLC        Edinburgh       31/01/2010      1.14
>
>
>
> I am trying to calculate the total change in share price like for CARDIFF PROPERTY PUBLIC LIMITED COMPANY the total change
>
> between 2005 and 2006 is NA and for 2006 and 2007 it is NA for 2007 and 2008 it is -3.1 and 2008 and 2009 it is 0 and 2009 and 2010 it is +.95.
>
>
> I am trying to achieve this via he following code:
>
> for (i in 1:(nrow(PLC)-1))
> if (isTRUE (PLC[i, 1] == PLC[i + 1, 1]))
> {
> PLC\$CH_SH_PRICE(i+1) = (PLC\$CLOSE_SHARE_PRICE[i+1] -
> PLC\$CLOSE_SHARE_PRICE[i])
> }
>
>
> I get the following error
>
>
> Error in 1:(nrow(PLC) - 1) : argument of length 0
>
>
> Can you kindly suggest any solution to this issue?
>
>
>          [[alternative HTML version deleted]]
>
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--
David K Stevens, P.E., Ph.D.
Professor, Environmental Engineering
Civil and Environmental Engineering
Utah Water Research Laboratory
8200 Old Main Hill
Logan, UT  84322-8200
435 797 3229 - voice
435 797 1363 - fax
david.stevens using usu.edu

```