[R] ?max (so far...)

[Mark Knecht]

Hi,
   I have a data.frame that is date ordered by row number - earliest
date first and most current last. I want to create a couple of new
columns that show the max and min values from other columns *so far* -
not for the whole data.frame.

   It seems this sort of question is really coming from my lack of
understanding about how R intends me to limit myself to portions of a
data.frame. I get the impression from the help files that the generic
way is that if I'm on the 500th row of a 1000 row data.frame and want
to limit the search max does to rows 1:500  I should use something
like [1:row] but it's not working inside my function. The idea works
outside the function, in the sense I can create tempt1[1:7] and the
max function returns what I expect. How do I do this with row?

   Simple example attached. hp should be 'highest p', ll should be
'lowest l'. I get an error message "Error in 1:row : NA/NaN argument"

Thanks,
Mark

AddCols = function (MyFrame) {
	MyFrame$p<-0
	MyFrame$l<-0
	MyFrame$pc<-0
	MyFrame$lc<-0
	MyFrame$pwin<-0
	MyFrame$hp<-0
	MyFrame$ll<-0
	return(MyFrame)
}

BinPosNeg = function (MyFrame) {

## Positive y in p column, negative y in l column
	pos <- MyFrame$y > 0
	MyFrame$p[pos] <- MyFrame$y[pos]
	MyFrame$l[!pos] <- MyFrame$y[!pos]
	return(MyFrame)
}

RunningCount = function (MyFrame) {
## Running count of p & l events

	pos <- (MyFrame$p > 0)
	MyFrame$pc <- cumsum(pos)
	pos <- (MyFrame$l < 0)
	MyFrame$lc <- cumsum(pos)

	return(MyFrame)
}

PercentWins = function (MyFrame) {
	
	MyFrame$pwin <- round((MyFrame$pc / (MyFrame$pc+MyFrame$lc)),2)

	return(MyFrame)
}

HighLow = function (MyFrame) {
	temp1 <- MyFrame$p[1:row]
	MyFrame$hp <- max(temp1) ## Highest p
	temp1 <- MyFrame$l[1:row]
	MyFrame$ll <- min(temp1) ## Lowest l

	return(MyFrame)
}

F1 <- data.frame(x=1:10, y=2*(-4:5) )
F1 <- AddCols(F1)
F1 <- BinPosNeg(F1)
F1 <- RunningCount(F1)
F1 <- PercentWins(F1)
F1
F1 <- HighLow(F1)
F1

temp1<-F1$p[1:5]
max(temp1)
temp1<-F1$p[1:7]
max(temp1)
temp1<-F1$p[1:10]
max(temp1)