[R] Extracting portions of one vector to create others

[Eric Berger]

Your request is equivalent to "how to do one-hot encoding in R". You can do
this search yourself.

Just for fun, I did that search and the following is a short solution:

A <- model.matrix(  ~ as.character(Beth$CLASS) - 1 )
colnames(A) <- paste0("CLASS", c(1,2,4,7,9))

A is now a matrix whose columns are the vectors that you want. To see this:

head(A)

  CLASS1 CLASS2 CLASS4 CLASS7 CLASS9
1           1             0              0             0           0
2           1             0              0             0           0
3           1             0              0             0           0
4           1             0              0             0           0
5           1             0              0             0           0
6           1             0              0             0           0

On Tue, Sep 2, 2025 at 10:07 AM Jeffrey Dick <j3ffdick using gmail.com> wrote:

> Hi Paul,
>
> Here's a way that creates new vectors as elements of a list.
>
> Beth <- list(
>  CLASS = c(1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,
> 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,
>    2, 2, 2, 2, 2, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4,
> 4, 4, 4, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7, 7,
>    7, 7, 7, 7, 7, 7, 7, 7, 7, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 9, 1
>  )
> )
>
> classes <- unique(Beth$CLASS)
>
> # Loop over `classes` to operate on a single `class` in each iteration
> result <- lapply(classes, function(class) {
>   # Create a vector with 1 if Beth$CLASS is in class, 0 if not
>   as.numeric(Beth$CLASS == class)
> })
>
> names(result) <- paste0("CLASS", classes)
>
> with the result:
>
> > result
> $CLASS1
> [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0
> [83] 0 0 0 0 0 0 0 0 0 0 0 0 0 1
>
> $CLASS2
> [1] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1
> 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0 0 0 0 0 0 0 0 0 0 0 0 0
> 0
> [83] 0 0 0 0 0 0 0 0 0 0 0 0 0 0
>
> [list truncated ...]
>
> Regards,
> Jeff
>
> On Tue, Sep 2, 2025 at 2:44 PM Paul Zachos <paz using acase.org> wrote:
> >
> > Dear Colleagues,
> >
> > I have a vector which indicates membership of subjects in one of 5
> Classes
> >
> > Beth$CLASS
> >  [1] 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 2 2 2 2 2
> 2 2
> > [37] 2 2 2 2 2 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 4 7 7 7 7 7 7 7 7 7
> 7 7
> > [73] 7 7 7 7 7 7 7 7 7 9 9 9 9 9 9 9 9 9 9 9 9 9 9 1
> >
> > For purposes of an analysis (using linear models based on Ward and
> Jennings) I would like to create 5 new vectors
> >
> > The values in vector CLASS1 will be ‘1’ if the corresponding value in
> Beth$CLASS is equal to ‘1’; ‘0’ otherwise
> >
> > The values in vector CLASS2 will be ‘1’ if the corresponding value in
> Beth$CLASS is equal to ‘2’; ‘0’ otherwise
> >
> > The values in vector CLASS4 will be ‘1’ if the corresponding value in
> Beth$CLASS is equal to ‘4’; ‘0’ otherwise
> >
> > The values in vector CLASS7 will be ‘1’ if the corresponding value in
> Beth$CLASS is equal to ‘7’; ‘0’ otherwise
> >
> > The values in vector CLASS9 will be ‘1’ if the corresponding value in
> Beth$CLASS is equal to ‘9’; ‘0’ otherwise
> >
> > How would I go about this using R
> >
> > Thank you
> > _________________
> > Paul Zachos, PhD
> > Director, Research and Evaluation
> > Association for the Cooperative Advancement of Science and Education
> (ACASE)
> > 110 Spring Street  Saratoga Springs, NY 12866  |
> > paz using acase.org  |  www.acase.org
> >
> >
> >
> >
> >
> >         [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide
> https://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
> ______________________________________________
> R-help using r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> https://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>

	[[alternative HTML version deleted]]