R help - Jun 2018 - printing an arbitrary-length character vector in columns on a page of a pdf report

I'm writing code for a recurring report, using an R --> Sweave -->
pdflatex
workflow. It includes a character vector of short words that I would like
to display compactly, in columns on a page, rather than one word per line,
which would waste a lot of space. The vector of words will increase
unpredictably over time, with future versions of the report.

I thought I would go about it by turning the character vector into a
matrix, as follows:

dd <- LETTERS
## set number of columns. Three for now
nc <- 3
## have to pad the character vector to a length that is multiple of nc
add <- nc - (length(dd) %% nc)
dd2 <- c(dd, rep("", add))
ddm <- matrix(dd2, ncol = nc)
library(Hmisc)
latex(ddm, file = "")

Any ideas for a more elegant way to do this?

Thanks.

--Chris Ryan
Binghamton University
and
Broome County Health Department
Binghamton, NY, US

	[[alternative HTML version deleted]]

> On Jun 5, 2018, at 9:45 AM, Christopher W Ryan <cryan at
binghamton.edu> wrote:
> 
> I'm writing code for a recurring report, using an R --> Sweave
--> pdflatex
> workflow. It includes a character vector of short words that I would like
> to display compactly, in columns on a page, rather than one word per line,
> which would waste a lot of space. The vector of words will increase
> unpredictably over time, with future versions of the report.
> 
> I thought I would go about it by turning the character vector into a
> matrix, as follows:
> 
> dd <- LETTERS
> ## set number of columns. Three for now
> nc <- 3
> ## have to pad the character vector to a length that is multiple of nc
> add <- nc - (length(dd) %% nc)
> dd2 <- c(dd, rep("", add))
> ddm <- matrix(dd2, ncol = nc)
> library(Hmisc)
> latex(ddm, file = "")
> 
> Any ideas for a more elegant way to do this?
> 
Use a LaTeX longtable environment (and add \usepackage{longtable} to the header
of your document). Put something like this in your *.Rnw file:

% longtable header goes here

<<results=tex>>cat( paste(dd, ifelse( seq(along = dd) %% 3 == 0,
"\\\\\n", "&")) )
@

% longtable footer goes here

should do it. But if there are exactly 3*k elements, you might skip the trailing
`\\'.

If you are unclear what the header/footer ought to look like try this:

HMisc::latex(ddm, file="", longtable=TRUE)

and you should figure it out.

HTH,

Chuck

I think this is cuter, and it is a hair faster.

n <- length(dd)
ddm <- matrix("", (n+2) %/% nc, nc)
ddm[1:n] <- dd

Rich

> system.time(for (i in 1:10000) {
+ add <- nc - (length(dd) %% nc)
+ dd2 <- c(dd, rep("", add))
+ ddm <- matrix(dd2, ncol = nc)
+ })
   user  system elapsed
  0.064   0.100   0.483
>
> system.time(for (i in 1:10000) {
+ n <- length(dd)
+ ddm <- matrix("", (n+2) %/% nc, nc)
+ ddm[1:n] <- dd
+ })
   user  system elapsed
  0.045   0.000   0.045

On Tue, Jun 5, 2018 at 12:45 PM, Christopher W Ryan
<cryan at binghamton.edu> wrote:
> I'm writing code for a recurring report, using an R --> Sweave
--> pdflatex
> workflow. It includes a character vector of short words that I would like
> to display compactly, in columns on a page, rather than one word per line,
> which would waste a lot of space. The vector of words will increase
> unpredictably over time, with future versions of the report.
>
> I thought I would go about it by turning the character vector into a
> matrix, as follows:
>
> dd <- LETTERS
> ## set number of columns. Three for now
> nc <- 3
> ## have to pad the character vector to a length that is multiple of nc
> add <- nc - (length(dd) %% nc)
> dd2 <- c(dd, rep("", add))
> ddm <- matrix(dd2, ncol = nc)
> library(Hmisc)
> latex(ddm, file = "")
>
> Any ideas for a more elegant way to do this?
>
> Thanks.
>
> --Chris Ryan
> Binghamton University
> and
> Broome County Health Department
> Binghamton, NY, US
>
>         [[alternative HTML version deleted]]
>
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Richard--

Nice. If I understand your code correctly, in the line

ddm <- matrix("", (n+2) %/% nc, nc)

I could instead use

ddm <- matrix("", (n + nc - 1) %/% nc, nc)

for generalizability, as I may have to increase nc as the list of words
grows ever longer.

Thanks everyone. Several good suggestions.

--Chris Ryan

Richard M. Heiberger wrote:
> n <- length(dd)
> ddm <- matrix("", (n+2) %/% nc, nc)
> ddm[1:n] <- dd