Hi R-help,
I am trying to create a for loop with multiple iteration indexes. I don't
want to use two different for loops nested together because I don't need
the full matrix of the two indexes, just the diagonal elements (e.g., i[1]
& j[1] and i[2] & j[2], but not i[1] & j[2]). Is there a way to
specify
both i and j in a single for loop? Here is a simplified example of
pseudo-code where x and y are equally sized character vectors with column
names and dat is their dataframe (obviously this code doesn't run in R, but
hopefully you perceive my goal):
r <- list()
n <- 0
for (i in x; j in y) {
n <- n + 1
r[[n]] <- cor(x = dat[, i], y = dat[, j])
}
print(r)
I realize there are other solutions to this particular correlation example,
but my actual problem is much more complicated, so I am hoping for a
solution that generalizes across any code within the for loop.
--
David J. Disabato, M.A.
Clinical Psychology Doctoral Student
George Mason University
ddisabat at gmu.edu
Email is not a secure form of communication as information and
confidentiality cannot be guaranteed. Information provided in an email is
not intended to be a professional service. In the case of a crisis or
emergency situation, call 911.
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Hi David, If you mean that you have two data frames named x and y and want the correlations between the columns that would be on the diagonal of a correlation matrix: r<-list() for(i in 1:n) r[[i]]<-cor(x[,i],y[,i]) If I'm wrong, let me know. Jim On Mon, Sep 10, 2018 at 3:06 PM David Disabato <ddisab01 at gmail.com> wrote:> > Hi R-help, > > I am trying to create a for loop with multiple iteration indexes. I don't > want to use two different for loops nested together because I don't need > the full matrix of the two indexes, just the diagonal elements (e.g., i[1] > & j[1] and i[2] & j[2], but not i[1] & j[2]). Is there a way to specify > both i and j in a single for loop? Here is a simplified example of > pseudo-code where x and y are equally sized character vectors with column > names and dat is their dataframe (obviously this code doesn't run in R, but > hopefully you perceive my goal): > > r <- list() > n <- 0 > for (i in x; j in y) { > n <- n + 1 > r[[n]] <- cor(x = dat[, i], y = dat[, j]) > } > print(r) > > I realize there are other solutions to this particular correlation example, > but my actual problem is much more complicated, so I am hoping for a > solution that generalizes across any code within the for loop. > > -- > David J. Disabato, M.A. > Clinical Psychology Doctoral Student > George Mason University > ddisabat at gmu.edu > > Email is not a secure form of communication as information and > confidentiality cannot be guaranteed. Information provided in an email is > not intended to be a professional service. In the case of a crisis or > emergency situation, call 911. > > [[alternative HTML version deleted]] > > ______________________________________________ > R-help at 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.
Hi,
this simple example is very similarly, and it works in R:
r <- list()
n <- 0
x <- c("a","b","c")#x,y: Data from a dataframe
y <- c("A","B","C")
for (k in 1:3) {
n <- n+1
r[[n]] <- paste0(x[k],y[k])#or any other function using x[k] and y[k] as
arguments
}
print(r)
Is it this what you meant?
Best,
Albrecht
--
Albrecht Kauffmann
alkauffm at fastmail.fm
Am Mo, 10. Sep 2018, um 00:49, schrieb David Disabato:> Hi R-help,
>
> I am trying to create a for loop with multiple iteration indexes. I
don't
> want to use two different for loops nested together because I don't
need
> the full matrix of the two indexes, just the diagonal elements (e.g., i[1]
> & j[1] and i[2] & j[2], but not i[1] & j[2]). Is there a way to
specify
> both i and j in a single for loop? Here is a simplified example of
> pseudo-code where x and y are equally sized character vectors with column
> names and dat is their dataframe (obviously this code doesn't run in R,
but
> hopefully you perceive my goal):
>
> r <- list()
> n <- 0
> for (i in x; j in y) {
> n <- n + 1
> r[[n]] <- cor(x = dat[, i], y = dat[, j])
> }
> print(r)
>
> I realize there are other solutions to this particular correlation example,
> but my actual problem is much more complicated, so I am hoping for a
> solution that generalizes across any code within the for loop.
>
> --
> David J. Disabato, M.A.
> Clinical Psychology Doctoral Student
> George Mason University
> ddisabat at gmu.edu
>
> Email is not a secure form of communication as information and
> confidentiality cannot be guaranteed. Information provided in an email is
> not intended to be a professional service. In the case of a crisis or
> emergency situation, call 911.
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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.
I have a sense of deja vu: https://www.mail-archive.com/r-help at r-project.org/msg250494.html There is some good advice there.> On Sep 9, 2018, at 3:49 PM, David Disabato <ddisab01 at gmail.com> wrote: > > Hi R-help, > > I am trying to create a for loop with multiple iteration indexes. I don't > want to use two different for loops nested together because I don't need > the full matrix of the two indexes, just the diagonal elements (e.g., i[1] > & j[1] and i[2] & j[2], but not i[1] & j[2]). Is there a way to specify > both i and j in a single for loop? Here is a simplified example of > pseudo-code where x and y are equally sized character vectors with column > names and dat is their dataframe (obviously this code doesn't run in R, but > hopefully you perceive my goal): > > r <- list() > n <- 0 > for (i in x; j in y) { > n <- n + 1 > r[[n]] <- cor(x = dat[, i], y = dat[, j]) > } > print(r) > > I realize there are other solutions to this particular correlation example, > but my actual problem is much more complicated, so I am hoping for a > solution that generalizes across any code within the for loop.A more aRtful way (than a for loop) to approach this is with mapply: i <- head(colnames(mtcars)) j <- tail(colnames(mtcars)) r <- mapply(function(i, j, dat) cor( x = dat[, i], y = dat[, j]), i=i , j=j , MoreArgs = list( dat = mtcars), SIMPLIFY = FALSE, USE.NAMES = FALSE) and if you want, maybe USE.NAMES = paste(i, j, sep="_") Chuck
Thank you everyone. After thinking about each response, I realized a fairly
simple solution is available (obviously, other suggested approaches work as
well):
stopifnot(length(x) == length(y); stopifnot(length(x) > 0)
r <- list()
for (i in 1:length(x) ) {
r[[i]] <- cor(x = dat[, x[i] ], y = dat[, y[i] ])
}
print(r)
On Mon, Sep 10, 2018 at 11:30 AM Berry, Charles <ccberry at ucsd.edu>
wrote:
> I have a sense of deja vu:
>
> https://www.mail-archive.com/r-help at r-project.org/msg250494.html
>
> There is some good advice there.
>
> > On Sep 9, 2018, at 3:49 PM, David Disabato <ddisab01 at
gmail.com> wrote:
> >
> > Hi R-help,
> >
> > I am trying to create a for loop with multiple iteration indexes. I
don't
> > want to use two different for loops nested together because I
don't need
> > the full matrix of the two indexes, just the diagonal elements (e.g.,
> i[1]
> > & j[1] and i[2] & j[2], but not i[1] & j[2]). Is there a
way to specify
> > both i and j in a single for loop? Here is a simplified example of
> > pseudo-code where x and y are equally sized character vectors with
column
> > names and dat is their dataframe (obviously this code doesn't run
in R,
> but
> > hopefully you perceive my goal):
> >
> > r <- list()
> > n <- 0
> > for (i in x; j in y) {
> > n <- n + 1
> > r[[n]] <- cor(x = dat[, i], y = dat[, j])
> > }
> > print(r)
> >
> > I realize there are other solutions to this particular correlation
> example,
> > but my actual problem is much more complicated, so I am hoping for a
> > solution that generalizes across any code within the for loop.
>
> A more aRtful way (than a for loop) to approach this is with mapply:
>
>
> i <- head(colnames(mtcars))
> j <- tail(colnames(mtcars))
>
> r <- mapply(function(i, j, dat) cor( x = dat[, i], y = dat[, j]),
> i=i , j=j , MoreArgs = list( dat = mtcars),
> SIMPLIFY = FALSE, USE.NAMES = FALSE)
>
>
> and if you want, maybe USE.NAMES = paste(i, j, sep="_")
>
> Chuck
>
>
--
David J. Disabato, M.A.
Clinical Psychology Doctoral Student
George Mason University
ddisabat at gmu.edu
Email is not a secure form of communication as information and
confidentiality cannot be guaranteed. Information provided in an email is
not intended to be a professional service. In the case of a crisis or
emergency situation, call 911.
[[alternative HTML version deleted]]