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. ______________________________________________ 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.
