Greetings,
I am trying to learn how to put the sum of several columns, by row (i.e., sum answers per subject), into a new column.
Looking at the documentation for "mutate_all {dplyr} starts off with:
Scoped verbs ( _if , _at , _all ) have been superseded by the use of across() in an existing verb. See vignette("colwise") for details.
From Console
> vignette("colwise")
Warning message:
vignette ‘colwise’ not found
Making 'packages.html' ... done
> vignette("colwise")
Warning message:
vignette ‘colwise’ not found
I assume that you have a dev version of dplyr installed? Latest CRAN version doesn't have the bit you've quoted in it. Since this is the case, it is probably didn't yet make it into release. Once dplyr maintainers are happy with the way it looks, it will be released along with dplyr 1.0.0.
But in general, to find all available vignettes, you can run browseVignettes() - it will bring up HTML page with all available vignettes. Or you can bring up help page for any of the functions in the package in question and then click on Index at the very bottom of the page. It will bring up the index page for all exported functions and there you'll have a link to "User guides, package vignettes and other documentation."
As @mishabalyasin says, you are using the development version of dplyr, which I am guessing you installed via:
devtools::install_github("tidyverse/dplyr")
Unlike install.packages() (which installs the stable version from CRAN), devtools::install_github() does not build the package vignettes by default. To get them, you should do: