Functions to check if an object is a data frame, or coerce it if possible.
as.data.frame(x, row.names = NULL, optional = FALSE, …)# S3 method for character
as.data.frame(x, …,
stringsAsFactors = default.stringsAsFactors())
# S3 method for list
as.data.frame(x, row.names = NULL, optional = FALSE, …,
cut.names = FALSE, col.names = names(x), fix.empty.names = TRUE,
stringsAsFactors = default.stringsAsFactors())
# S3 method for matrix
as.data.frame(x, row.names = NULL, optional = FALSE,
make.names = TRUE, …,
stringsAsFactors = default.stringsAsFactors())
is.data.frame(x)
any R object.
NULL or a character vector giving the row
names for the data frame. Missing values are not allowed.
logical. If TRUE, setting row names and
converting column names (to syntactic names: see
make.names) is optional. Note that all of R's
base package as.data.frame() methods use
optional only for column names treatment, basically with the
meaning of data.frame(*, check.names = !optional).
See also the make.names argument of the matrix method.
additional arguments to be passed to or from methods.
logical: should the character vector be converted to a factor?
logical or integer; indicating if column names with
more than 256 (or cut.names if that is numeric) characters
should be shortened (and the last 6 characters replaced by " ...").
(optional) character vector of column names.
logical indicating if empty column names, i.e.,
"" should be fixed up (in data.frame) or not.
a logical, i.e., one of FALSE, NA, TRUE,
indicating what should happen if the row names (of the matrix
x) are invalid. If they are invalid, the default,
TRUE, calls make.names(*, unique=TRUE);
make.names=NA will use “automatic” row names and a
FALSE value will signal an error for invalid row names.
as.data.frame returns a data frame, normally with all row names
"" if optional = TRUE.
is.data.frame returns TRUE if its argument is a data
frame (that is, has "data.frame" amongst its classes)
and FALSE otherwise.
as.data.frame is a generic function with many methods, and
users and packages can supply further methods. For classes that act
as vectors, often a copy of as.data.frame.vector will work
as the method.
If a list is supplied, each element is converted to a column in the
data frame. Similarly, each column of a matrix is converted separately.
This can be overridden if the object has a class which has
a method for as.data.frame: two examples are
matrices of class "model.matrix" (which are
included as a single column) and list objects of class
"POSIXlt" which are coerced to class
"POSIXct".
Arrays can be converted to data frames. One-dimensional arrays are treated like vectors and two-dimensional arrays like matrices. Arrays with more than two dimensions are converted to matrices by ‘flattening’ all dimensions after the first and creating suitable column labels.
Character variables are converted to factor columns unless protected
by I.
If a data frame is supplied, all classes preceding "data.frame"
are stripped, and the row names are changed if that argument is supplied.
If row.names = NULL, row names are constructed from the names
or dimnames of x, otherwise are the integer sequence
starting at one. Few of the methods check for duplicated row names.
Names are removed from vector columns unless I.
Chambers, J. M. (1992) Data for models. Chapter 3 of Statistical Models in S eds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.
data.frame, as.data.frame.table for the
table method (which has additional arguments if called directly).