Re: [R] Vertical subtraction in dataframes

2010-03-13 Thread nowfocus
It depends how you stored your missing values. If they are listed as NAs then mydataframe$calib <- Count - is.na(stain)*Count or mydataframe$calib <- Count*(1 - is.na(stain)) The trick is the boolean 'TRUE' equals 1 in numeric calculations. -- View this message in context: http://n4.nabble.c

Re: [R] Vertical subtraction in dataframes

2010-03-12 Thread Gabor Grothendieck
And here is one more SQL solution. This one uses the window functions in PostgreSQL and is slightly more compact and even closer to the pure R version in our prior post. We quote Count so its not regarded as the reserved word of the same name. Note that if RpgSQL is loaded then sqldf will automati

Re: [R] Vertical subtraction in dataframes

2010-03-12 Thread Gabor Grothendieck
Try this ave solution noting that summing Count * (stain == "none") over each group gives the Count in its stain=="none" row and ave causes that Count value to be repeated for every row of the group so we get a vector that can be subtracted from Count: transform(DF, calib = Count - ave(Count * (st

Re: [R] Vertical subtraction in dataframes

2010-03-12 Thread David Winsemius
On Mar 12, 2010, at 5:27 PM, Sam Albers wrote: Hello all, I have not been able to find an answer to this problem. I feel like it might be so simple though that it might not get a response. Suppose I have a dataframe like the one I have copied below (minus the 'calib' column). I wish to cre

Re: [R] Vertical subtraction in dataframes

2010-03-12 Thread Dennis Murphy
Hi: Here's a ddply solution to your problem (package plyr): library(plyr) # within group function to apply; assumes that 'none' is first obs in group # x will be the Count variable in the call... subt2 <- function(x) x - x[1] head(df) rep Count stain 11 1522.0none 21 147.0

Re: [R] Vertical subtraction in dataframes

2010-03-12 Thread Jonathan Christensen
Hello, On Fri, Mar 12, 2010 at 3:27 PM, Sam Albers wrote: > Hello all, > > I have not been able to find an answer to this problem. I feel like it > might > be so simple though that it might not get a response. > > Suppose I have a dataframe like the one I have copied below (minus the > 'calib' co

[R] Vertical subtraction in dataframes

2010-03-12 Thread Sam Albers
Hello all, I have not been able to find an answer to this problem. I feel like it might be so simple though that it might not get a response. Suppose I have a dataframe like the one I have copied below (minus the 'calib' column). I wish to create a column like calib where I am subtracting the 'Co