Hi list, I have a function that detects saccadic eye movements in a time series of eye positions sampled at a rate of 250Hz. This function needs three vectors: x-coordinate, y-coordinate, trial-id. This information is usually contained in a data frame that also has some other fields. The names of the fields are not standardized.
> head(eyemovements) time x y trial 51 880446504 53.18 375.73 1 52 880450686 53.20 375.79 1 53 880454885 53.35 376.14 1 54 880459060 53.92 376.39 1 55 880463239 54.14 376.52 1 56 880467426 54.46 376.74 1 There are now several possibilities for the signature of the function: 1. Passing the columns separately: detect(eyemovements$x, eyemovements$y, eyemovements$trial) or: with(eyemovements, detect(x, y, trial)) 2. Passing the data frame plus the names of the fields: detect(eyemovements, "x", "y", "trial") 3. Passing the data frame plus a formula specifying the relevant fields: detect(eyemovements, ~x+y|trial) 4. Passing a formula and getting the data from the environment: with(eyemovements, detect(~x+y|trial)) I saw instances of all those variants (and others) in the wild. Is there a canonical way to tell a function which fields in a data frame are relevant? What other alternatives are possible? What are the pros and cons of the alternatives? Thanks, Titus ______________________________________________ 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.