New user here. My goal is pull daily averages from a long dataset. I've been working with some code I got from this list from
https://stat.ethz.ch/pipermail/r-help/2009-March/191302.html The code how I have been using it is as follows: library(zoo) library(chron) DB<-read.table("/Users/me/Desktop/R/data.csv", sep=",", header=TRUE, as.is =TRUE) z<-zoo(LTER6$temp, chron(LTER6$Date, LTER6$Time)) z.day=aggregate(z, trunc, mean) #This last line gives me daily averages for my data Simple and elegant- and it works. Thanks to the author the hard part is over. But I plan to tweak it so I have some questions about why this works 1- The data I have has the date and time format as a single string like this "2006-04-09 10:20:00". But the code was set up to read the data in two columns ie- "2006-04-09" & "10:20:00". Is this how the chrom package expects to have the data, or is there a way I can change the code to read the data as a single column. For now I am chopping up my date and time data manually before I run R. 2- I've read the help on "as.is", and I'm not sure why I need that function in the first line of code. This is what my original data looks like (with header) if this helps answer this this question line.site,time_local,time_utc,reef_type_code,sensor_type,sensor_depth_m,temp 06,2006-04-09 10:20:00,2006-04-09 20:20:00,BAK,sb39, 2, 29.63 06,2006-04-09 10:40:00,2006-04-09 20:40:00,BAK,sb39, 2, 29.56 3. Finally- how does the function "trunc" know to aggregate the data by day? If I wanted to do monthly averages I would need to specify with "as.yearmon", but I don't seem to need to specify "day" anywhere in the code. Thanks in advance. Your help has saved me multiple hours of spreadsheet time. [[alternative HTML version deleted]] ______________________________________________ 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.
