if else statements in R

An embedded and charset-unspecified text was scrubbed...
Name: not available
Url: https://stat.ethz.ch/pipermail/r-help/attachments/20030630/1e81dada/attachment.pl
Hola!
Hi, there

I am a grad student struggling to get my syntax right in a model I am 
building in R.

I am trying to specify a variable,W, in a loop, such that on the first 
iteration, it is equal to Wo, my starting value, which I have already 
specified with

Wo<-9.2

  On any other iteration other than the first, I want W to equal the 
previous value of W in the iteration. plus an increment from that previous 
iteration, divided by another value.  This then becomes the value used in 
all calculations in the iteration at hand.

Here is my code, that does not work:
There are multiple problems with this code
1)  You use W as a name of a function AND as a name of an array 
inside that function. Might not be a syntax error (?), but is asking 
for problems. Use an other name for your array, and assign it first.
2) The variable i is not given a value anywhere in your code.
3)The condition in the if statement uses = and not ==, = is 
assignment, == is test lfor equality. Actuallt, your comp[i,1] gets 
assigned 1, that is also the value of the assignment, and in the 
logical test the 1 will be interpreted as TRUE, so you will never get 
the else branch!
W<- function(w)
{
if (comp[i,1]=1) W[i]<-Wo else
W[i]<-(work[i-1,5]work[i-1,13]*/Ef)
}
Maybe youwant something like:

W <- function(w) {
    result <- numeric(length=?)
    if (comp[i,1]==1) result[i] <- W0 else
          result[i] <- work[i-1,5] * work[i-1,13]/Ef
}

but it is really impossible to tell, as your function are using 
global variables. Another good idea is to avoid global variables.

Kjetil Halvorsen

"work" is the dataframe that I am rbinding my interations into, and the W 
variable is the 5th variable in that frame, and the additive to W is the 
13th variable in that frame.

However, this is where the program stalls on me:

{
+
+ W<- function(w)
+ {
+ if (comp[i,1]=1) W[i]<-Wo else
Error: syntax error
Execution halted

I've also attempted this variation;

W<- function(w)

if (comp[i,1]=1) {W[i]<-Wo} else
W[i]<-(work[i-1,5]work[i-1,13]*/Ef)

Which meets with an equal lack of success, and stalls in the same spot as 
the previous version.

Does anyone have any hints on how to make this if else statement work to do 
what I need?  This is my first time trying to use these statements, and the 
S-plus manual i have is proving to be terribly unhelpful.

What am I doing wrong?

Mike

Michael Rennie
M.Sc. Candidate
University of Toronto at Mississauga
3359 Mississauga Rd. N.
Mississauga, ON  L5L 1C6
Ph: 905-828-5452  Fax: 905-828-3792
	[[alternative HTML version deleted]]

______________________________________________
R-help at stat.math.ethz.ch mailing list
https://www.stat.math.ethz.ch/mailman/listinfo/r-help