Hi Brian, I believe there was some miscommunication earlier due to R's array class for objects and the colloquial usage of array (the idea that 'array' is used colloquially is a bit odd, but I digress). In any case, here are some steps I take (certainly not the only ones) when exploring a new dataset that I am not familiar with:
## load the package library(PASWR) ## look at the str()ucture of the object of interest str(StatTemps) ## Hmm, it is a 'data.frame' with 3 variables ## one variable is 'num' and the other two are 'Factor' ## let's see if we can find out more about those data classes ## (pull up the documentation on each, it can be hard to know at first ## that 'num' stands for numeric and 'Factor' needs to be lowercase) ?data.frame ?numeric ?factor ## in this case, it is easy to print the whole data set so StatTemps # print to screen ## but you can also get a nice little summary summary(StatTemps) ## For the documentation on extraction/indexing ?Extract ## and some examples StatTemps$temperature StatTemps$gender StatTemps$class ## now using a different operator than '$' ## You can call by name by quoting StatTemps[ , "temperature"] ## or since we know it is column 1 StatTemps[ , 1] ## conversely, we can get row 1 StatTemps[1, ] ## or some combination of rows StatTemps[c(1:7, 22:34), ] ## or rows and columns StatTemps[c(1:7, 22:34), c(1, 3)] ## But since you have a factor, there may be an easier way subset(StatTemps, gender == "Male") subset(StatTemps, gender == "Female") subset(StatTemps, class == "8 a.m.") subset(StatTemps, class == "9 a.m.") ## on more than one variable subset(StatTemps, class == "8 a.m." & gender == "Male") ## with a continuous variable subset(StatTemps, temperature < 94) ## and we can do calculations by() groups by(data = StatTemps$temperature, INDICES = StatTemps$gender, FUN = mean) ## but typing the name is annoying with(StatTemps, by(data = temperature, INDICES = gender, FUN = mean)) ## even more detailed (but leaving off the explicit argument names) with(StatTemps, by(temperature, list(gender, class), mean)) ## A couple visual summaries boxplot(temperature ~ gender, data = StatTemps) boxplot(temperature ~ class, data = StatTemps) ## or hop on over to lattice for something a little more advanced bwplot(temperature ~ gender | class, data = StatTemps) ## and you can select certain parts without subset() ## first let's see what happens with StatTemps$gender == "Female" ## now if you pass a logical vector to the extraction operator, '[' StatTemps[StatTemps$gender == "Female", ] ## same thing but just the first column StatTemps[StatTemps$gender == "Female", 1] ## That came out as a vector, but StatTemps[StatTemps$gender == "Female", 1, drop = FALSE] HTH, Josh On Mon, Nov 29, 2010 at 5:01 AM, bfhancock <brianfhanc...@gmail.com> wrote: > > if you can load the PASWR package and pull up StatTemps you will see what I > am talking about. Otherwise I fear that my question will just be confusing. > -- > View this message in context: > http://r.789695.n4.nabble.com/Array-help-tp3062992p3063535.html > Sent from the R help mailing list archive at Nabble.com. > > ______________________________________________ > 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. > -- Joshua Wiley Ph.D. Student, Health Psychology University of California, Los Angeles http://www.joshuawiley.com/ ______________________________________________ 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.
