On Apr 10, 2009, at 3:40 PM, Shadley Thomas wrote:

Hi Everyone,

I'm new to programming R and have accomplished my goal, but feel that there
is probably a more efficient way of coding this.  I'd appreciate any
guidance that a more advanced programmer can provide.

My goal --
I would like to find the length of the longest word in a string containing
many words separated by spaces.

How I did it --
I was able to find the length of the longest word by parsing the string into a list of separate words, using the function "which.max" to determine the element with the longest length, and then using "nchar" to calculate the
length of that particular word.

My question --
It seems inefficient to determine which element is the longest and then calculate the length of that longest element. I was hoping to find a way to simply return the length of the longest word in a more straightforward way.

Short sample code --
shadstr <- c("My string of words with varying lengths. Longest word is
nine - 1 22 333 999999999 4444")
shadvector <- unlist(strsplit(shadstr, split=" "))
shadvlength <- lapply(shadvector,nchar)
shadmaxind <- which.max(shadvlength) ## Maximum element
shadmax <- nchar(shadvector[shadmaxind])
shadmax
[1] 9

Many thanks for your help and suggestions.
Shad

Welcome to R Shad.

Note that the 'x' argument to nchar() can be a vector, which means that it will return the character lengths of the individual elements of the vector. Thus:

# Get the individual components, I use list indexing here, but unlist() works as well
> strsplit(shadstr, " ")[[1]]
 [1] "My"        "string"    "of"        "words"     "with"
 [6] "varying"   "lengths."  ""          "Longest"   "word"
[11] "is"        "nine"      "-"         "1"         "22"
[16] "333"       "999999999" "4444"

# Get the lengths of each
> nchar(strsplit(shadstr, " ")[[1]])
 [1] 2 6 2 5 4 7 8 0 7 4 2 4 1 1 2 3 9 4

# Get the max length
> max(nchar(strsplit(shadstr, " ")[[1]]))
[1] 9


As an aside, note that there are two spaces between the period '.' and the word "Longest", which results in an empty element in the resultant vector. If you wanted to split on one or more spaces, you could use a 'regular expression' in strsplit() such as:

> strsplit(shadstr, " +")[[1]]
 [1] "My"        "string"    "of"        "words"     "with"
 [6] "varying"   "lengths."  "Longest"   "word"      "is"
[11] "nine"      "-"         "1"         "22"        "333"
[16] "999999999" "4444"

In the above, the use of " +" says to match one or more spaces as the split character. See ?regex for more information on that point.

HTH,

Marc Schwartz

______________________________________________
R-help@r-project.org mailing list
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.

Reply via email to