On Thu, 3 Jul 2014 12:34:42 PM Marta valdes lopez wrote: > Thank you Jim for your answer.Ok alpha( it is the speed of the boat) is a > range of number from 0.5 to 10 like 0.5,1,1.5,2...., I would like to have > the mean of x and y base on each value of alpha, because I have like ten > numbers of x for each value of speed, thats why I want the mean of that and > them i could create the roc plot with the new values. > I would say that alpha values are ordered already? > > Thanks , Marta > Hi Marta, The variable "alpha" should be numeric and shouldn't cause the error you described. If you get this result:
is.numeric(alpha) FALSE then "alpha" has been converted to a factor somehow. This usually happens when one or more values of alpha can't be read as a number in the read.csv step. It doesn't seem like your dataset is very large, so perhaps you could print alpha: alpha and see if anything doesn't look like a number. You may be able to track this back to the CSV file and correct a typo or something. Jim ______________________________________________ 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.
