Hi, I am trying to aggregate some data and I am confused by the results. I load a data frame "all" from a csv file, and then I do: (FOO,BAR,X,Y come from the header line in the csv file, BTW, how do I rename a column?)
byFOO <- aggregate(list(all$BAR,all$QUUX,all$X/all$Y), by = list(FOO=all$FOO), FUN = mean); I expect a data frame with 4 columns: FOO,BAR,QUUX and X/Y with all FOO being different (they are character strings, do I need a special incantation to turn them into factors?) what I get is indeed a data frame but with names [1] "FOO" [2] "c.1.78e.11..4.38e.09..1.461e.11..4.3186e.10..1.1181e.10..5.5389e.10.." [3] "c.33879300..3713870..190963000..7042170..4590010..91569200..12108200.." [4] "c.1.37087599544937..1.72690992018244..1.82034830430797..1.70338983050847.." why? how do I fix the column names? then I am trying to add to that same frame byFOO some other columns: byFOO$Count <- aggregate(all$FOO, by = list(all$FOO), FUN = length); byFOO$Mean <- aggregate(all$Value, by = list(all$FOO), FUN = mean); byFOO$Total <- aggregate(all$Value, by = list(all$FOO), FUN = sum); however, byFOO$Count et al are not columns in byFOO with the appropriate names ("Count" &c) but data frames with columns "Group.1" and "x". Luckily, at least it appears that byFOO$Count$Group.1 is the same as byFOO$FOO, as they should be, although I don't see any function which would check that two vectors are the same ("==" returns a vector which I have to manually inspect for presence of "FALSE"). So, how do I aggregate the data frame? How do I rename a column? How do I check that two vectors are the same? thanks a lot! PS. I have not used R for a few years, so please be gentle... PPS. Please do not tell me to RTFM - I did. At least tell me what to search for. -- Sam Steingold (http://sds.podval.org/) on CentOS release 5.3 (Final) http://dhimmi.com http://camera.org http://palestinefacts.org http://memri.org http://jihadwatch.org http://ffii.org http://pmw.org.il There are 10 kinds of people: those who count in binary and those who do not. ______________________________________________ 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.