[R] data frame manipulation change elements meeting criteria

[arnaud Gaboury]

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 at gmail.com] 
Sent: Thursday, May 27, 2010 8:43 AM
To: arnaud Gaboury
Cc: r-help at 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 at 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 at gmail.com]
Sent: Wednesday, May 26, 2010 9:15 PM
To: arnaud Gaboury
Cc: r-help at 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 at 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

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--
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 at 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 at Ugent.be 
-------------------------------
Disclaimer : http://helpdesk.ugent.be/e-maildisclaimer.php