On 07/25/2020 04:17 PM, Jeff Newmiller 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. >>> Thank you, code corrected and problem solved. I was thrown off by the fact that after mutating it looked like the column data type had been changed. I also tried mutate_at() which similarly failed...
______________________________________________ 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.
