| as.data.frame {base} | R Documentation |
Functions to check if an object is a data frame, or coerce it if possible.
as.data.frame(x, row.names = NULL, optional = FALSE) is.data.frame(x)
x |
any R object. |
row.names |
NULL or a character vector giving the row
names for the data frame. Missing values are not allowed. |
optional |
logical. If TRUE, setting row names and
converting column names (to syntactic names) is optional. |
as.data.frame is a generic function with many methods, and
users and packages can supply further methods.
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"
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.
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.
In versions of R prior to 1.4.0 logical columns were converted to factors (as in S3 but not S4).
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.