print.default Default Printing

Description

print.default is the default method of the generic print function which prints its argument.

Usage

## Default S3 method:
print(x, digits = NULL, quote = TRUE,
      na.print = NULL, print.gap = NULL, right = FALSE,
      max = NULL, width = NULL, useSource = TRUE, ...)

Arguments

x	the object to be printed.
digits	a non-null value for digits specifies the minimum number of significant digits to be printed in values. The default, NULL, uses getOption("digits"). (For the interpretation for complex numbers see signif.) Non-integer values will be rounded down, and only values greater than or equal to 1 and no greater than 22 are accepted.
quote	logical, indicating whether or not strings (characters) should be printed with surrounding quotes.
na.print	a character string which is used to indicate NA values in printed output, or NULL (see ‘Details’).
print.gap	a non-negative integer ≤ 1024, or NULL (meaning 1), giving the spacing between adjacent columns in printed vectors, matrices and arrays.
right	logical, indicating whether or not strings should be right aligned. The default is left alignment.
max	a non-null value for max specifies the approximate maximum number of entries to be printed. The default, NULL, uses getOption("max.print"): see that help page for more details.
width	controls the maximum number of columns on a line used in printing vectors, matrices, etc. The default, NULL, uses getOption("width"): see that help page for more details including allowed values.
useSource	logical, indicating whether to use source references or copies rather than deparsing language objects. The default is to use the original source if it is available.
...	further arguments to be passed to or from other methods. They are ignored in this function.

Details

The default for printing NAs is to print NA (without quotes) unless this is a character NA and quote = FALSE, when <NA> is printed.

The same number of decimal places is used throughout a vector. This means that digits specifies the minimum number of significant digits to be used, and that at least one entry will be encoded with that minimum number. However, if all the encoded elements then have trailing zeroes, the number of decimal places is reduced until at least one element has a non-zero final digit. Decimal points are only included if at least one decimal place is selected.

Attributes are printed respecting their class(es), using the values of digits to print.default, but using the default values (for the methods called) of the other arguments.

Option width controls the printing of vectors, matrices and arrays, and option deparse.cutoff controls the printing of language objects such as calls and formulae.

When the methods package is attached, print will call show for R objects with formal classes (‘S4’) if called with no optional arguments.

Large number of digits

Note that for large values of digits, currently for digits >= 16, the calculation of the number of significant digits will depend on the platform's internal (C library) implementation of sprintf() functionality.

Single-byte locales

If a non-printable character is encountered during output, it is represented as one of the ANSI escape sequences (\a, \b, \f, \n, \r, \t, \v, \\ and \0: see Quotes), or failing that as a 3-digit octal code: for example the UK currency pound sign in the C locale (if implemented correctly) is printed as \243. Which characters are non-printable depends on the locale. (Because some versions of Windows get this wrong, all bytes with the upper bit set are regarded as printable on Windows in a single-byte locale.)

Unicode and other multi-byte locales

In all locales, the characters in the ASCII range (0x00 to 0x7f) are printed in the same way, as-is if printable, otherwise via ANSI escape sequences or 3-digit octal escapes as described for single-byte locales. Whether a character is printable depends on the current locale and the operating system (C library).

Multi-byte non-printing characters are printed as an escape sequence of the form \uxxxx or \Uxxxxxxxx (in hexadecimal). This is the internal code for the wide-character representation of the character. If this is not known to be Unicode code points, a warning is issued. The only known exceptions are certain Japanese ISO 2022 locales on commercial Unixes, which use a concatenation of the bytes: it is unlikely that R compiles on such a system.

It is possible to have a character string in a character vector that is not valid in the current locale. If a byte is encountered that is not part of a valid character it is printed in hex in the form \xab and this is repeated until the start of a valid character. (This will rapidly recover from minor errors in UTF-8.)

See Also

The generic print, options. The "noquote" class and print method.

encodeString, which encodes a character vector the way it would be printed.

Examples

pi
print(pi, digits = 16)
LETTERS[1:16]
print(LETTERS, quote = FALSE)

M <- cbind(I = 1, matrix(1:10000, ncol = 10,
                         dimnames = list(NULL, LETTERS[1:10])))
utils::head(M)        # makes more sense than
print(M, max = 1000)  # prints 90 rows and a message about omitting 910