Print Values
Description
print prints its argument and returns it invisibly (via
invisible(x)). It is a generic function which means that
new printing methods can be easily added for new class es.
Usage
print(x, ...)
## S3 method for class 'factor'
print(x, quote = FALSE, max.levels = NULL,
width = getOption("width"), ...)
## S3 method for class 'table'
print(x, digits = getOption("digits"), quote = FALSE,
na.print = "", zero.print = "0",
right = is.numeric(x) || is.complex(x),
justify = "none", ...)
## S3 method for class 'function'
print(x, useSource = TRUE, ...)
Arguments
x
an object used to select a method.
...
further arguments passed to or from other methods.
quote
logical, indicating whether or not strings should be printed with surrounding quotes.
max.levels
integer, indicating how many levels should be
printed for a factor; if 0, no extra "Levels" line will be
printed. The default, NULL, entails choosing max.levels
such that the levels print on one line of width width.
width
only used when max.levels is NULL, see above.
digits
minimal number of significant digits, see
print.default .
na.print
character string (or NULL) indicating
NA values in printed output, see
print.default .
zero.print
character specifying how zeros (0) should be
printed; for sparse tables, using "." can produce more
readable results, similar to printing sparse matrices in Matrix.
right
logical, indicating whether or not strings should be right aligned.
justify
character indicating if strings should left- or
right-justified or left alone, passed to format .
useSource
logical indicating if internally stored source
should be used for printing when present, e.g., if
options(keep.source = TRUE) has been in use.
Details
The default method, print.default has its own help page.
Use methods("print") to get all the methods for the
print generic.
print.factor allows some customization and is used for printing
ordered factors as well.
print.table for printing table s allows other
customization. As of R 3.0.0, it only prints a description in case of a table
with 0-extents (this can happen if a classifier has no valid data).
See noquote as an example of a class whose main
purpose is a specific print method.
References
Chambers, J. M. and Hastie, T. J. (1992) Statistical Models in S. Wadsworth & Brooks/Cole.
See Also
The default method print.default , and help for the
methods above; further options , noquote .
For more customizable (but cumbersome) printing, see
cat , format or also write .
For a simple prototypical print method, see
.print.via.format in package tools.
Examples
require(stats)
ts(1:20) #-- print is the "Default function" --> print.ts(.) is called
for(i in 1:3) print(1:i)
## Printing of factors
attenu$station ## 117 levels -> 'max.levels' depending on width
## ordered factors: levels "l1 < l2 < .."
esoph$agegp[1:12]
esoph$alcgp[1:12]
## Printing of sparse (contingency) tables
set.seed(521)
t1 <- round(abs(rt(200, df = 1.8)))
t2 <- round(abs(rt(200, df = 1.4)))
table(t1, t2) # simple
print(table(t1, t2), zero.print = ".") # nicer to read
## same for non-integer "table":
T <- table(t2,t1)
T <- T * (1+round(rlnorm(length(T)))/4)
print(T, zero.print = ".") # quite nicer,
print.table(T[,2:8] * 1e9, digits=3, zero.print = ".")
## still slightly inferior to Matrix::Matrix(T) for larger T
## Corner cases with empty extents:
table(1, NA) # < table of extent 1 x 0 >