Truncate Strings and Add Ellipses If a String is Truncated.

Truncates one or more strings to a specified length, adding an ellipsis (...) to those strings that have been truncated. The truncation can also be performed using word boundaries. Use StrAlign() to justify the strings if needed.

StrTrunc(x, maxlen = 20, ellipsis = "...", wbound = FALSE)

Arguments

x

a vector of strings.

maxlen

the maximum length of the returned strings (NOT counting the appended ellipsis). maxlen is recycled.

ellipsis

the string to be appended, if the string is longer than the given maximal length. The default is "...".

wbound

logical. Determines if the maximal length should be reduced to the next smaller word boundary and so words are not chopped. Default is FALSE.

Value

The string(s) passed as x now with a maximum length of maxlen + 3 (for the ellipsis).

Author

Andri Signorell,
once following an idea of Jim Lemon in truncString()

See also

String functions: nchar, match, grep, regexpr, substr, sub, gsub, StrTrim, StrDist

Examples

x <- c("this is short", "and this is a longer text", 
       "whereas this is a much longer story, which could not be told shorter")

# simple truncation on 10 characters
StrTrunc(x, maxlen=10)
#> [1] "this is sh..." "and this i..." "whereas th..."

# NAs remain NA
StrTrunc(c(x, NA_character_), maxlen=15, wbound=TRUE)
#> [1] "this is short"     "and this is a ..." "whereas this ..." 
#> [4] NA                 

# using word boundaries
for(i in -5:20)
  print(StrTrunc(x, maxlen=i, wbound=TRUE))
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "t..." "a..." "w..."
#> [1] "th..." "an..." "wh..."
#> [1] "thi..." "and..." "whe..."
#> [1] "this..." "and ..." "wher..."
#> [1] "this ..." "and ..."  "where..."
#> [1] "this ..."  "and ..."   "wherea..."
#> [1] "this ..."   "and ..."    "whereas..."
#> [1] "this is ..." "and ..."     "whereas ..."
#> [1] "this is ..."  "and this ..." "whereas ..." 
#> [1] "this is ..."  "and this ..." "whereas ..." 
#> [1] "this is ..."  "and this ..." "whereas ..." 
#> [1] "this is ..."     "and this is ..." "whereas ..."    
#> [1] "this is short"    "and this is ..."  "whereas this ..."
#> [1] "this is short"     "and this is a ..." "whereas this ..." 
#> [1] "this is short"     "and this is a ..." "whereas this ..." 
#> [1] "this is short"       "and this is a ..."   "whereas this is ..."
#> [1] "this is short"       "and this is a ..."   "whereas this is ..."
#> [1] "this is short"         "and this is a ..."     "whereas this is a ..."
#> [1] "this is short"         "and this is a ..."     "whereas this is a ..."
#> [1] "this is short"         "and this is a ..."     "whereas this is a ..."

# compare
for(i in -5:20)
  print(StrTrunc(x, maxlen=i, wbound=FALSE))
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "..." "..." "..."
#> [1] "t..." "a..." "w..."
#> [1] "th..." "an..." "wh..."
#> [1] "thi..." "and..." "whe..."
#> [1] "this..." "and ..." "wher..."
#> [1] "this ..." "and t..." "where..."
#> [1] "this i..." "and th..." "wherea..."
#> [1] "this is..." "and thi..." "whereas..."
#> [1] "this is ..." "and this..." "whereas ..."
#> [1] "this is s..." "and this ..." "whereas t..."
#> [1] "this is sh..." "and this i..." "whereas th..."
#> [1] "this is sho..." "and this is..." "whereas thi..."
#> [1] "this is shor..." "and this is ..." "whereas this..."
#> [1] "this is short"    "and this is a..." "whereas this ..."
#> [1] "this is short"     "and this is a ..." "whereas this i..."
#> [1] "this is short"      "and this is a l..." "whereas this is..."
#> [1] "this is short"       "and this is a lo..." "whereas this is ..."
#> [1] "this is short"        "and this is a lon..." "whereas this is a..."
#> [1] "this is short"         "and this is a long..." "whereas this is a ..."
#> [1] "this is short"          "and this is a longe..." "whereas this is a m..."
#> [1] "this is short"           "and this is a longer..."
#> [3] "whereas this is a mu..."