[R] Modifying dataframe with mutate()
Patrick (Malone Quantitative)
m@|one @end|ng |rom m@|onequ@nt|t@t|ve@com
Sat Jul 25 21:59:06 CEST 2020
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 <jdnewmil using dcn.davis.ca.us>
> 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 <agents using 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:
> >v1 still shows as int. Do I need to save the modified dataframe after
> >mutating a variable?
> >R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> >PLEASE do read the posting guide
> >and provide commented, minimal, self-contained, reproducible code.
> Sent from my phone. Please excuse my brevity.
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> PLEASE do read the posting guide
> and provide commented, minimal, self-contained, reproducible code.
Patrick S. Malone, Ph.D., Malone Quantitative
NEW Service Models: http://malonequantitative.com
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