Hello Christopher and others : What cannot be stressed enough is: do not combine both packages, it gives errors and incorrect results! I will show that below -------------------------------------------------------- a<-data.frame(groep=1:4,v=1:40) library(dplyr) a %>% group_by(groep) %>% summarise(m=mean(v),n=n()) # groep m n # <int> <dbl> <int> # 1 1 19 10 # 2 2 20 10 # 3 3 21 10 # 4 4 22 10 # correct
library(plyr) a %>% group_by(groep) %>% summarise(m=mean(v),n=n()) Error in n() : This function should not be called directly # ??? a %>% group_by(groep) %>% summarise(m=mean(v)) # m # 1 20.5 #incorrect! -------------------------------------------------- So both n() and group_by from dplyr don't work after library(plyr)! My advice is: do not use plyr. Unfortunately plyr has some functions that are very important, and that are not in dplyr. For instance: rbind.fill() (for combining the rows of two dataframes with unequal columns). If you need this: do'nt library plyr, use plyr::rbind.fil Until now I have the impression that it is also possible to library dplyr after plyr, but it is better to remove plyr! This is a serious problem that has been reported before, but not solved (in dplyr 0.5.0 and plyr 1.8.4) Frams 2016-09-15 16:09 GMT+02:00 Christopher W Ryan <cr...@binghamton.edu>: > I've set myself the task of learning about these packages, and about > tidy data concepts. > > What is the relationship between plyr and dplyr? Does the latter > replace the former (meaning I can concentrate on learning the latter)? > Or is there ever a need to use functions from both (meaning I should > learn both)? > > Thanks. > > --Chris Ryan > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. > [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
