Peter et al, I had the same thought, in particular for any() and all(), which in as much as they should work on data.frames in the first place (which to be perfectly honest i do find quite debatable myself), should certainly work on "logical" data.frames if they are going to work on "numeric" ones.
I can volunteer to prepare a patch if Martin (the reporter) did not want to take a crack at it, and further if it is not already being done within R-core. Best, ~G On Sun, Oct 18, 2020 at 12:19 AM peter dalgaard <pda...@gmail.com> wrote: > Hmm, yes, this is probably wrong. E.g., we are likely to get > inconsistencies out of boundary cases like this > > > a <- na.omit(airquality) > > sum(a) > [1] 37495.3 > > sum(a[FALSE,]) > Error in FUN(X[[i]], ...) : > only defined on a data frame with all numeric variables > > Or, closer to an actual use case: > > > sum(subset(a, Ozone>100)) > [1] 3330.5 > > sum(subset(a, Ozone>200)) > Error in FUN(X[[i]], ...) : > only defined on a data frame with all numeric variables > > > However, given that numeric summaries generally treat logicals as 0/1, > wouldn't it be easiest just to extend the check inside Summary.data.frame > with "&& !is.logical(x)"? > > > sum(as.matrix(a[FALSE,])) > [1] 0 > > -pd > > > On 17 Oct 2020, at 21:18 , Martin <r...@mb706.com> wrote: > > > > The "Summary" group generics always throw errors for a data.frame with > zero rows, for example: > >> sum(data.frame(x = numeric(0))) > > #> Error in FUN(X[[i]], ...) : > > #> only defined on a data frame with all numeric variables > > Same behaviour for min, max, any, all, ... . I believe this is > inconsistent with what these methods do for other empty objects (vectors, > matrices), where the return value is chosen to ensure transitivity: > sum(numeric(0)) == 0. > > > > The reason for this is that the return type of as.matrix() for empty (no > rows or no columns) data.frame objects is always a matrix of type > "logical". The Summary method for data.frame, in turn, throws an error when > the data.frame, converted to a matrix, is not of numeric type. > > > > I suggest two ways that make sum, min, max, ... more consistent. IMHO it > would be fitting to implement both of these fixes, because they also make > other things more consistent. > > > > 1. Make the return type of as.matrix() for zero-row data.frames > consistent with the type that would have been returned, had the data.frame > had more than zero rows. "as.matrix(data.frame(x = numeric(0)))" should > then be numeric, if there is an empty "character" column the return matrix > should be a character etc. This would make subsetting by row and conversion > to matrix commute (except for row names sometimes): > >> all.equal(as.matrix(df[rows, , drop = FALSE]), as.matrix(df)[rows, , > drop = FALSE]) > > Furthermore, this change would make as.matrix.data.frame obey the > documentation, which indicates that the coercion hierarchy is used for the > return type. > > > > 2. Make the Summary.data.frame method accept data.frames that produce > non-numeric matrices. Next to the main focus of this message, I believe it > would e.g. be fitting to have any() and all() work on logical data.frame > objects. The current behaviour is such that > >> any(data.frame(x = 1)) > > #> [1] TRUE > > #> Warning message: > > #> In any(1, na.rm = FALSE) : coercing argument of type 'double' to > logical > > and > >> any(data.frame(x = TRUE)) > > #> Error in FUN(X[[i]], ...) : > > #> only defined on a data frame with all numeric variables > > So a numeric data.frame warns about implicit coercion, while a logical > data.frame (which would not need coercion) does not work at all. > > > > (I feel more strongly about fixing 1. than 2., because I don't know the > discussion that lead to the behaviour described in 2.) > > > > Best, > > Martin > > > > ______________________________________________ > > R-devel@r-project.org mailing list > > https://stat.ethz.ch/mailman/listinfo/r-devel > > -- > Peter Dalgaard, Professor, > Center for Statistics, Copenhagen Business School > Solbjerg Plads 3, 2000 Frederiksberg, Denmark > Phone: (+45)38153501 > Office: A 4.23 > Email: pd....@cbs.dk Priv: pda...@gmail.com > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel > [[alternative HTML version deleted]] ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
