Oh, right--I puzzled out my mistake. On Sat, Jul 25, 2020 at 4:17 PM Jeff Newmiller <jdnew...@dcn.davis.ca.us> wrote:
> False. Mutate is similar in structure to the base function `within`. Which > is why you have to assign the altered data frame back onto itself. > > On July 25, 2020 12:59:06 PM PDT, "Patrick (Malone Quantitative)" < > mal...@malonequantitative.com> wrote: > >Jeff, > > > >mutate(), which is I think part of dplyr, also violates this, for what > >it's > >worth. I suspect the breaking point is that mutate() is intended to > >create > >new columns in the dataframe, not alter existing ones. > > > >On Sat, Jul 25, 2020 at 3:52 PM Jeff Newmiller > ><jdnew...@dcn.davis.ca.us> > >wrote: > > > >> R is largely a functional language. You do something to an input and > >end > >> up with an output that has no effect on the input. This is actually a > >> highly desirable feature. > >> > >> If you want your df variable to reflect changes made then you need > >to > >> assign your result back into it. > >> > >> df <- df %>% mutate(v1 = as.double(v1)) > >> > >> (Note that the data.table package violates this principle and is > >> controversial as a result.) > >> > >> On July 25, 2020 12:11:24 PM PDT, H <age...@meddatainc.com> wrote: > >> >In a statement like: > >> > > >> >df %>% mutate(v1 = as.double(v1)) > >> > > >> >I expect the variable v1 in dataframe df to have been converted into > >a > >> >double. However, when I do: > >> > > >> >str(df) > >> > > >> >v1 still shows as int. Do I need to save the modified dataframe > >after > >> >mutating a variable? > >> > > >> >______________________________________________ > >> >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. > >> > >> -- > >> Sent from my phone. Please excuse my brevity. > >> > >> ______________________________________________ > >> 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. > >> > > -- > Sent from my phone. Please excuse my brevity. > -- Patrick S. Malone, Ph.D., Malone Quantitative NEW Service Models: http://malonequantitative.com He/Him/His [[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.
