tapply confusion
On Aug 29, 2012, at 7:37 AM, andyspeak wrote:
Hello I have a huge data frame with three columns 'Roof' 'Month' and 'Temp' i want to run analyses on the numerical Temp data by the factors Roof and Month, separately and together. For using more than one factor i understand i should use aggregate, but i am struggling with the tapply for single factor analysis.
tapply(Temp, INDEX = Roof, FUN = median)
This works fine, however if i try to do anything a bit more complex, such as:
tapply(Temp, INDEX = Roof, FUN = kruskal.test)
it gives the error - Error in length(g) : 'g' is missing
What is the sound of one hand clapping? You are sending a bunch of single vectors with no grouping variable to a function that is expecting two data columns. Maybe you should explain what test you had in mind using natural language and we could help get you there.
David Winsemius, MD Alameda, CA, USA