[R] assigning letter to a column

Fri Oct 17 16:27:33 CEST 2014

Minor correction, given your code, values less than 3 will be coded as "S" since they are less than 15.23. In the code I suggested, values less than 3 will be coded as missing (NA).

David C

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of David L Carlson
Sent: Friday, October 17, 2014 9:15 AM
To: Monaly Mistry; r-help at r-project.org
Subject: Re: [R] assigning letter to a column

I think it is doing exactly what you have told it to do, but that is probably not what you want it to do.

First, you do not need a loop since the ifelse() function is vectorized. Read the manual page and the examples carefully. Also you are coding ifelse() as if it were the same as if() {} else() {}. Again you need to refer to the documentation.

Second, this seems like a job for cut() not ifelse().

Third, look at your code. The first statement is x$COR_LOC>=3 | x$COR_LOC<15.230 so everything greater than 3 will be coded as "S." That is probably all of your data. You probably want to use & (and) instead of | (or). It is not clear what you want to happen for values less than 3 but they will be NA (missing).

Your entire ifelse() boils down to

set.seed(42)
x <- data.frame(COR_LOC=runif(100, 0, 30))
x$ForS <- cut(x$COR_LOC, breaks=c(3, 15.23, 19.81, 25.40, Inf),
	labels=c("S", "I1", "I2", "F"), right=FALSE)

No loops, no ifelse's. Anything below 3 will 

-------------------------------------
David L Carlson
Department of Anthropology
Texas A&M University
College Station, TX 77840-4352

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Monaly Mistry
Sent: Friday, October 17, 2014 8:27 AM
To: r-help at r-project.org
Subject: [R] assigning letter to a column

Hi,

I'm having trouble with assigning a letter to a column based on the value
of another column.
Since I have separate data files I've saved then into one folder and I'm
reading them in separately into the function.

The code is below.

#F= fast; S= slow; I1= Intermediate score 1; I2=Intermediate score 2
filename<-list.files(pattern="*.txt")
filename
corloc<- function(x){
  x<-read.table(filename[x], sep="\t", header=TRUE) #will extract the
relevant data file from folder 1998. ex. corloc(1) will return 1998
breeding year data
  x[,"ForS"]<-0 #new column
  for (i in length(x$CORLOC)){ #this is the bit that I'm having a problem
with since it's not assigning the appropriate letter into the "ForS" column
  ifelse(x$COR_LOC>=3 | x$COR_LOC<15.230, ForS<-"S",
         ifelse(x$COR_LOC>=15.230 | x$COR_LOC<19.810, ForS<-"I1",
                ifelse(x$COR_LOC>=19.810 | x$COR_LOC<25.540,
FS<-"I2",ForS<-"F")))}
  print(x)
}

I've tried some of the solutions on stackoverflow but still was
unsuccessful.

Best,

Monaly.

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