On 9 Apr 2008, at 09:51, [EMAIL PROTECTED] wrote: >> I have the following data called mydata in a data.frame >> >> Col1 Col2 Col3 Col4 Col5 >> 1 2 4 6 7 >> 8 8 7 3 5 >> 4 4 5 6 7 >> >> I want to replace the data according to the following conditions >> >> Condition 1 if data <= 3, replace with -1 >> Condition 2 if data >=6, replace with 1 >> Condition 3 if data = 4 or data =5, replace with 0 >> >> So the expected output for the example, would be >> Col1 Col2 Col3 Col4 Col5 >> -1 -1 0 1 1 >> 1 1 1 -1 0 >> 0 0 1 1 1 > mydata[mydata<=3] = -1 > mydata[mydata==4 | mydata==5] = 0 > mydata[mydata>=6] = 1
An other more restrictive approach would be IF the matrix' cells are positive integer values in a definite range you can set up a vector containing the results of the conditions for each index representing the matrix cell content: cond <- c(-1, -1, -1, 0, 0, 1, 1, 1) and invoke: apply(mydata, 2, function(x) cond[x]) or even shorter: apply(mydata, 2, function(x) c(-1, -1, -1, 0, 0, 1, 1, 1)[x]) ======= If you haven't got a definite range and only a few conditions this is also possible: apply( mydata, 2, function(x) ifelse(x<=3,-1, ifelse(x>=6,1, ifelse(x==4|x==5,0,x))) ) Kind regards, --Hans ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
