Ah, OK. sapply -evidently- only gives an output for every case that goes in.
Which is only one, as there is only one DEL case. You can use that output to
change the corresponding value in the dataframe, like :

tradenews <- trades
tradenews$Buy.Sell..Cleared.[which(trades$Trade.Status=="DEL")] <-
     sapply(trades$Buy.Sell..Cleared.[which(trades$Trade.Status=="DEL")],
    switch,Sell="Buy",Buy="Sell")

Also take a look at these help files and the examples mentioned in there.
?switch
?sapply
?which

And please, give your variables some decent names. All those points make
your code very error-prone.

Cheers
Joris

On Thu, May 27, 2010 at 10:47 AM, arnaud Gaboury
<arnaud.gaboury@gmail.com>wrote:

> Sorry Joris, but I am totally lost on this issue!!
>
>
>
> >tradenews<-sapply(trades$Buy.Sell..Cleared[which(trades$Trade.Status=="DEL"
> )],switch,Sell="Buy",Buy="Sell")
>
> > tradenews
>  Sell
> "Buy"
>
> Not really what I want !!
>
> From: Joris Meys [mailto:jorismeys@gmail.com]
> Sent: Thursday, May 27, 2010 10:38 AM
> To: arnaud Gaboury
> Cc: r-help@r-project.org
> Subject: Re: [R] data frame manipulation change elements meeting criteria
>
> Off course. You put in a matrix to sapply, but sapply is for vectors. You
> want to apply the switch command on every entry of the vector
> trades$Buy.Sell..Cleared for which trades$Trade.Status equals "DEL". Why do
> you try to put in a matrix with all variables for the observations where
> status is DEL?
>
> You should have done :
>
>
> tradesnew<-sapply(trades$Buy.Sell..Cleared[which(trades$Trade.Status=="DEL")
> ],
>      switch,Sell="Buy",Buy="Sell")
>
> Check the help files, and keep track of what goes in and out a function.
>
> Cheers
> Joris
> On Thu, May 27, 2010 at 9:41 AM, arnaud Gaboury <arnaud.gaboury@gmail.com>
> wrote:
> Joris,
>
> If i pass this line :
>
> >tradesnew<-sapply(trades[which(trades$Trade.Status=="DEL"),],switch,Sel
> >l="Buy",Buy="Sell")
>
> Here is what I get :
>
> > tradesnew
> $Trade.Status
> NULL
>
> $Instrument.Long.Name
> NULL
>
> $Delivery.Prompt.Date
> NULL
>
> $Buy.Sell..Cleared.
> [1] "Buy"
>
> $Volume
> [1] "Buy"
>
> $Price
> NULL
>
> $Net.Charges..sum.
> NULL
>
> That's certainly not what I want.
>
>
>
>
> From: Joris Meys [mailto:jorismeys@gmail.com]
> Sent: Thursday, May 27, 2010 8:43 AM
> To: arnaud Gaboury
> Cc: r-help@r-project.org
> Subject: Re: [R] data frame manipulation change elements meeting criteria
>
> The loop is due to the switch statement, not the condition. Without
> condition it would become:
>
> for (i in 1:length(Y)){
>     new.vect[i]<-switch(
>           EXPR = X[i],
>           Sell="Buy",
>           Buy="Sell",
>           X[i])
> }
> You can make an sapply construct too off course :
>
> new.vect <- sapply(X[which(Y=="DEL")],switch,Sell="Buy",Buy="Sell")
>
> This will speed up things a little bit, but the effect is marginal.
> Cheers
> Joris
> On Thu, May 27, 2010 at 8:33 AM, arnaud Gaboury <arnaud.gaboury@gmail.com>
> wrote:
> Thank you for the answer.
> Is there any way to combine if() and switch() in one line? In my case,
> something like :
>
> >if(trade$Trade.Status=="DEL")switch(.....)
>
> I would like to avoid the loop .
>
>
>
> From: Joris Meys [mailto:jorismeys@gmail.com]
> Sent: Wednesday, May 26, 2010 9:15 PM
> To: arnaud Gaboury
> Cc: r-help@r-project.org
> Subject: Re: [R] data frame manipulation change elements meeting criteria
>
> see ?switch
>
> X<- rep(c("Buy","Sell","something else"),each=5)
> Y<- rep(c("DEL","INS","DEL"),5)
>
>
> new.vect <- X
> for (i in which(Y=="DEL")){
>     new.vect[i]<-switch(
>           EXPR = X[i],
>           Sell="Buy",
>           Buy="Sell",
>           X[i])
> }
> cbind(new.vect,X,Y)
> On Wed, May 26, 2010 at 7:43 PM, arnaud Gaboury <arnaud.gaboury@gmail.com>
> wrote:
> Dear group,
>
> Here is my df :
>
> trade <-
> structure(list(Trade.Status = c("DEL", "INS", "INS"), Instrument.Long.Name=
> c("SUGAR NO.11",
> "CORN", "CORN"), Delivery.Prompt.Date = c("Jul/10", "Jul/10",
> "Jul/10"), Buy.Sell..Cleared. = c("Sell", "Buy", "Buy"), Volume = c(1L,
> 2L, 1L), Price = c("15.2500", "368.0000", "368.5000"), Net.Charges..sum. =
> c(4.01,
> -8.64, -4.32)), .Names = c("Trade.Status", "Instrument.Long.Name",
> "Delivery.Prompt.Date", "Buy.Sell..Cleared.", "Volume", "Price",
> "Net.Charges..sum."), row.names = c(NA, 3L), class = "data.frame")
>
> Here is what I want :
>
> If trade$Trade.Status=="DEL": then if trade$buy.Sell..Cleared==Sell ,
> change
> it to "Buy", if trade$buy.Sell..Cleared==Buy, change it to "Sell".
> If trade$Trade.Status=="INS", do nothing
> I tried to work around with ifelse, but don't know how to deal with so many
> conditions.
>
> Any help is appreciated.
>
> TY
>
> ______________________________________________
> R-help@r-project.org mailing list
> 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.
>
>
>
> --
> Joris Meys
> Statistical Consultant
>
> Ghent University
> Faculty of Bioscience Engineering
> Department of Applied mathematics, biometrics and process control
>
> Coupure Links 653
> B-9000 Gent
>
> tel : +32 9 264 59 87
> Joris.Meys@Ugent.be
> -------------------------------
> Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
>
>
>
> --
> Joris Meys
> Statistical Consultant
>
> Ghent University
> Faculty of Bioscience Engineering
> Department of Applied mathematics, biometrics and process control
>
> Coupure Links 653
> B-9000 Gent
>
> tel : +32 9 264 59 87
> Joris.Meys@Ugent.be
> -------------------------------
> Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
>
>
>
> --
> Joris Meys
> Statistical Consultant
>
> Ghent University
> Faculty of Bioscience Engineering
> Department of Applied mathematics, biometrics and process control
>
> Coupure Links 653
> B-9000 Gent
>
> tel : +32 9 264 59 87
> Joris.Meys@Ugent.be
> -------------------------------
> Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php
>
>


-- 
Joris Meys
Statistical Consultant

Ghent University
Faculty of Bioscience Engineering
Department of Applied mathematics, biometrics and process control

Coupure Links 653
B-9000 Gent

tel : +32 9 264 59 87
Joris.Meys@Ugent.be
-------------------------------
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php

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