If I have data (below) and need some help in figuring out how I can change the values of my date column, so that a year will be from September-August? So the year 
1990 = September 89-August 90; 1991
 = September 90-August 91, etc... 

I was trying to use the if() function, but am unable to figure it out. I basically need to change the years associated with September-December to the following year. Any 
help would be greatly appreciated. Otherwise I will have to power through
 it and do it all manually in excel. I am sorry that I do not have the original data associated with this posting, nor any R code with it. I really do not have a clue how to even start designating the new year. 

head(mydata)
class(mydata)
"data.frame"
         site            date                precipitation temp_max temp_min
1 Castle Peak January-70             0       32       18
2 Castle Peak January-70             0       39        9
3 Castle Peak January-70             0       34        5
4 Castle Peak January-70             0       30        7
5 Castle Peak January-70             0       40        6
6 Castle Peak January-70             0       45       10

Thank you in advance and please let me know what else I can include to help solve this issue. this is my first posting on R-help. 



Nick Pardikes
PhD Student
Program in Ecology, Evolution and Conservation Biology
University of Nevada, Reno
303-550-1072
http://wolfweb.unr.edu/homepage/npardikes/MySite/Welcome.html
 		 	   		  
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