R: Encode in a Common Format

format {base} | R Documentation

## Encode in a Common Format

### Description

Format an R object for pretty printing: `format.pval` is intended for formatting p-values.

### Usage

    format(x, ...)
    format.AsIs(x, width = 12, ...)
    format.data.frame(x, ..., justify = "none")
    format.default(x, trim = FALSE, digits = getOption("digits"),
                   nsmall = 0, justify = c("left", "right", "none"), ...)
    format.factor(x, ...)
    format.pval(pv, digits = max(1, getOption("digits") - 2),
                eps = .Machine$double.eps, na.form = "NA")

### Arguments

`x` | any R object (conceptually); typically numeric.
`trim` | logical; if `TRUE`, leading blanks are trimmed off the strings.
`digits` | how many significant digits are to be used for `numeric x`. This is a suggestion: enough decimal places will be used so that the smallest (in magnitude) number has this many significant digits.
`nsmall` | number of digits which will always appear to the right of the decimal point in formatting real/complex numbers in non-scientific formats. Allowed values `0 <= nsmall <= 20`.
`justify` | should character vector be left-justified, right-justified or left alone. When justifying, the field width is that of the longest string.
`pv` | a numeric vector.
`eps` | a numerical tolerance: see Details.
`na.form` | character representation of `NA`s.
`width` | the returned vector has elements of at most `width`.
`...` | further arguments passed to or from other methods.

### Details

These functions convert their first argument to a vector (or array) of character strings which have a common format (as is done by `print`), fulfilling `length(format*(x, *)) == length(x)`. The trimming with `trim = TRUE` is useful when the strings are to be used for plot `axis` annotation.

`format.AsIs` deals with columns of complicated objects that have been extracted from a data frame.

`format.pval` is mainly an auxiliary function for `print.summary.lm` etc., does separate formatting for fixed, floating point and very small values (those `< eps`).

The function `formatC` provides a rather more flexible formatting facility for numbers, but does not provide a common format for several numbers, nor it is platform-independent.

`format.data.frame` formats the data frame column by column, applying the appropriate method of `format` for each column.

### Note

Currently `format` drops trailing zeroes, so `format(6.001, digits=2)` gives `"6"` and `format(c(6.0, 13.1), digits=2)` gives `c(" 6", "13")`.

Character(s) `"` in input strings `x` are escaped to `\"`.

### See Also

`formatC`, `paste`, `as.character`.

### Examples

    format(1:10)

    zz <- data.frame("(row names)"= c("aaaaa", "b"), check.names=FALSE)
    format(zz)
    format(zz, justify="left")

    ## use of nsmall
    format(13.7)
    format(13.7, nsmall=3)

    ## handling of quotes
    zz <- data.frame(a=I("abc"), b=I("def\"gh"))
    format(zz)

    p <- c(47,13,2,.1,.023,.0045, 1e-100)/1000
    format.pval(p)
    format.pval(p / 0.9)
    format.pval(p / 0.9, dig=3)

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