Compactly display the internal structure of an R object, a
diagnostic function and an alternative to summary
(and to some extent, dput). Ideally, only one line for
each ‘basic’ structure is displayed. It is especially well suited
to compactly display the (abbreviated) contents of (possibly nested)
lists. The idea is to give reasonable output for any R
object. It calls args for (non-primitive) function objects.
strOptions() is a convenience function for setting
options(str = .), see the examples.
str(object, …)# S3 method for data.frame
str(object, …)
# S3 method for default
str(object, max.level = NA,
vec.len = strO$vec.len, digits.d = strO$digits.d,
nchar.max = 128, give.attr = TRUE,
drop.deparse.attr = strO$drop.deparse.attr,
give.head = TRUE, give.length = give.head,
width = getOption("width"), nest.lev = 0,
indent.str = paste(rep.int(" ", max(0, nest.lev + 1)),
collapse = ".."),
comp.str = "$ ", no.list = FALSE, envir = baseenv(),
strict.width = strO$strict.width,
formatNum = strO$formatNum, list.len = 99, …)
strOptions(strict.width = "no", digits.d = 3, vec.len = 4,
drop.deparse.attr = TRUE,
formatNum = function(x, ...)
format(x, trim = TRUE, drop0trailing = TRUE, ...))
any R object about which you want to have some information.
maximal level of nesting which is applied for displaying nested structures, e.g., a list containing sub lists. Default NA: Display all nesting levels.
numeric (>= 0) indicating how many ‘first few’ elements
are displayed of each vector. The number is multiplied by different
factors (from .5 to 3) depending on the kind of vector. Defaults to
the vec.len component of option "str" (see
options) which defaults to 4.
number of digits for numerical components (as for
print). Defaults to the digits.d component of
option "str" which defaults to 3.
maximal number of characters to show for
character strings. Longer strings are truncated, see
longch example below.
logical; if TRUE (default), show attributes
as sub structures.
logical; if TRUE (default),
deparse(control = <S>) will not have
"showAttributes" in <S>. Used to be hard coded to
FALSE and hence can be set via strOptions() for back
compatibility.
logical; if TRUE (default), indicate
length (as [1:…]).
logical; if TRUE (default), give (possibly
abbreviated) mode/class and length (as <type>[1:…]).
the page width to be used. The default is the currently
active options("width"); note that this has only a
weak effect, unless strict.width is not "no".
current nesting level in the recursive calls to
str.
the indentation string to use.
string to be used for separating list components.
logical; if true, no ‘list of …’ nor the class are printed.
the environment to be used for promise (see
delayedAssign) objects only.
string indicating if the width argument's
specification should be followed strictly, one of the values
c("no", "cut", "wrap"), which can be abbreviated.
Defaults to the strict.width component of option "str"
(see options) which defaults to "no" for back
compatibility reasons; "wrap" uses
strwrap(*, width = width) whereas "cut" cuts
directly to width. Note that a small vec.length
may be better than setting strict.width = "wrap".
numeric; maximum number of list elements to display within a level.
potential further arguments (required for Method/Generic reasons).
str does not return anything, for efficiency reasons.
The obvious side effect is output to the terminal.
ls.str for listing objects with their structure;
summary, args.
# NOT RUN {
require(stats); require(grDevices); require(graphics)
## The following examples show some of 'str' capabilities
str(1:12)
str(ls)
str(args) #- more useful than args(args) !
str(freeny)
str(str)
str(.Machine, digits.d = 20) # extra digits for identification of binary numbers
str( lsfit(1:9, 1:9))
str( lsfit(1:9, 1:9), max.level = 1)
str( lsfit(1:9, 1:9), width = 60, strict.width = "cut")
str( lsfit(1:9, 1:9), width = 60, strict.width = "wrap")
op <- options(); str(op) # save first;
# otherwise internal options() is used.
need.dev <-
!exists(".Device") || is.null(.Device) || .Device == "null device"
{ if(need.dev) postscript()
str(par())
if(need.dev) graphics.off()
}
ch <- letters[1:12]; is.na(ch) <- 3:5
str(ch) # character NA's
str(list(a = "A", L = as.list(1:100)), list.len = 9)
## ------------
## " .. [list output truncated] "
## Long strings, 'nchar.max'; 'strict.width' :
nchar(longch <- paste(rep(letters,100), collapse = ""))
str(longch)
str(longch, nchar.max = 52)
str(longch, strict.width = "wrap")
## Multibyte characters in strings (in multibyte locales):
oloc <- Sys.getlocale("LC_CTYPE")
mbyte.lc <- if(.Platform$OS.type == "windows")
"English_United States.28605" else "en_GB.UTF-8"
try(Sys.setlocale("LC_CTYPE", mbyte.lc))
## Truncation behavior (<-> correct width measurement) for "long" non-ASCII:
idx <- c(65313:65338, 65345:65350)
fwch <- intToUtf8(idx) # full width character string: each has width 2
ch <- strtrim(paste(LETTERS, collapse="._"), 64)
(ncc <- c(c.ch = nchar(ch), w.ch = nchar(ch, "w"),
c.fw = nchar(fwch), w.fw = nchar(fwch, "w")))
stopifnot(unname(ncc) == c(64,64, 32, 64))
## nchar.max: 1st line needs an increase of 2 in order to see 1 (in UTF-8!):
invisible(lapply(60:66, function(N) str(fwch, nchar.max = N)))
invisible(lapply(60:66, function(N) str( ch , nchar.max = N))) # "1 is 1" here
## revert locale to previous:
Sys.setlocale("LC_CTYPE", oloc)
## Settings for narrow transcript :
op <- options(width = 60,
str = strOptions(strict.width = "wrap"))
str(lsfit(1:9,1:9))
str(options())
## reset to previous:
options(op)
# }
# NOT RUN {
str(quote( { A+B; list(C, D) } ))
# }
# NOT RUN {
<!-- % package attaching/detaching only when needed: -->
# }
# NOT RUN {
## S4 classes :
require(stats4)
x <- 0:10; y <- c(26, 17, 13, 12, 20, 5, 9, 8, 5, 4, 8)
ll <- function(ymax = 15, xh = 6)
-sum(dpois(y, lambda=ymax/(1+x/xh), log=TRUE))
fit <- mle(ll)
str(fit)
# }
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