Coerce to a Data Frame

Description

Functions to check if an object is a data frame, or coerce it if possible.

Usage

as.data.frame(x, row.names = NULL, optional = FALSE, ...)## S3 method for class 'character'as.data.frame(x, ...,              stringsAsFactors = FALSE)## S3 method for class 'list'as.data.frame(x, row.names = NULL, optional = FALSE, ...,              cut.names = FALSE, col.names = names(x), fix.empty.names = TRUE,              check.names = !optional,              stringsAsFactors = FALSE)## S3 method for class 'matrix'as.data.frame(x, row.names = NULL, optional = FALSE,              make.names = TRUE, ...,              stringsAsFactors = FALSE)is.data.frame(x)

Arguments

Details

as.data.frame is a generic function with many methods, andusers and packages can supply further methods. For classes that actas vectors, often a copy ofas.data.frame.vector will workas the method.

If a list is supplied, each element is converted to a column in thedata frame. Similarly, each column of a matrix is converted separately.This can be overridden if the object has a class which hasa method foras.data.frame: two examples arematrices of class"model.matrix" (which areincluded 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 aretreated like vectors and two-dimensional arrays like matrices. Arrayswith more than two dimensions are converted to matrices by‘flattening’ all dimensions after the first and creatingsuitable column labels.

Character variables are converted to factor columns unless protectedbyI.

If a data frame is supplied, all classes preceding"data.frame"are stripped, and the row names are changed if that argument is supplied.

Ifrow.names = NULL, row names are constructed from the namesor dimnames ofx, otherwise are the integer sequencestarting at one. Few of the methods check for duplicated row names.Names are removed from vector columns unlessI.

Value

as.data.frame returns a data frame, normally with all row names"" ifoptional = TRUE.

is.data.frame returnsTRUE if its argument is a dataframe (that is, has"data.frame" amongst its classes)andFALSE otherwise.

References

Chambers, J. M. (1992)Data for models.Chapter 3 ofStatistical Models in Seds J. M. Chambers and T. J. Hastie, Wadsworth & Brooks/Cole.

See Also

data.frame,as.data.frame.table for thetable method (which has additional arguments if called directly).