Re: [R] concatenate vector after strsplit()

[Robert Baer]

Thanks Jorge and David.  Both worked.  Looks like I have to read more on "[" 
as an extractor function for lists.  do.call() is also on my list of "low 
level magic' I don't understand. <G>   Appreciate the help!

fil1 = do.call(c, lapply(lapply(ls1, "[", 1:4), paste, sep = "", collapse = 
"-"))
fil2 = sapply(lapply(ls1, "[", 1:4), paste, collapse="-")
ls1 <- list(c("Focused", "10k", "A12", "t04.tif", "+", "µm"), 
c("Focused",
"10k", "A12", "t08.tif", "+", "µm"), c("Focused", "10k", "A12",
"t12.tif", "+", "µm"), c("Focused", "10k", "A12", "t16.tif",
"+", "µm"), c("Focused", "10k", "A12", "t20.tif", "+", "µm"),
  c("Focused", "10k", "A12", "t24.tif", "+", "µm"), c("Focused",
  "10k", "A12", "t36.tif", "+", "µm"), c("Focused", "10k",
  "A12", "t48.tif", "+", "µm"), c("Focused", "10k", "B12",
  "t04.tif", "+", "µm"), c("Focused", "10k", "B12", "t08.tif",
  "+", "µm"))

Perhaps:

> sapply(ls1, paste, collapse="")
[1] "Focused10kA12t04.tif+µm" "Focused10kA12t08.tif+µm"
[3] "Focused10kA12t12.tif+µm" "Focused10kA12t16.tif+µm"
[5] "Focused10kA12t20.tif+µm" "Focused10kA12t24.tif+µm"
[7] "Focused10kA12t36.tif+µm" "Focused10kA12t48.tif+µm"
[9] "Focused10kB12t04.tif+µm" "Focused10kB12t08.tif+µm"

(I changed the name and will not illustrate its assignment to  "file". It 
is generally considered poor programming practice  to use  function names 
for variable objects.)

I suppose it would be better practice on my part to read the question 
more thoroughly:

> sapply(lapply(ls1, "[", 1:4), paste, collapse="")
 [1] "Focused10kA12t04.tif" "Focused10kA12t08.tif"
 [3] "Focused10kA12t12.tif" "Focused10kA12t16.tif"
 [5] "Focused10kA12t20.tif" "Focused10kA12t24.tif"
 [7] "Focused10kA12t36.tif" "Focused10kA12t48.tif"
 [9] "Focused10kB12t04.tif" "Focused10kB12t08.tif"

--
David.

# Test the waters with one element
cat(unlist(ls[1])[1:4])      # WHY DOES THE COMMAND PROMPT NOT  APPEAR 
ON NEXT LINE AS USUAL???

# Appears to work except for command prompt glitch

# Attempts to use tapply() don't get me anywhere
file <- tapply(unlist(ls), list(1:length(unlist(ls))), 
cat(unlist(ls[1])[1:4]))

I'm grateful for an approach to putting my vector together, but I'd 
also love to understand the headache I've apparently given the  command 
parser.  I'm apparently doing some "no no".

Thanks,

Rob

R.Version()
$platform
[1] "i386-pc-mingw32"

$arch
[1] "i386"

$os
[1] "mingw32"

$system
[1] "i386, mingw32"

$status
[1] ""

$major
[1] "2"

$minor
[1] "12.1"

$year
[1] "2010"

$month
[1] "12"

$day
[1] "16"

$`svn rev`
[1] "53855"

$language
[1] "R"

$version.string
[1] "R version 2.12.1 (2010-12-16)"



David Winsemius, MD
West Hartford, CT

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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.