first.word {Hmisc} | R Documentation

## First Word in a String or Expression

### Description

`first.word` finds the first word in an expression. A word is defined by unlisting the elements of the expression found by the S parser and then accepting any elements whose first character is either a letter or period. The principal intended use is for the automatic generation of temporary file names where it is important to exclude special characters from the file name. For Microsoft Windows, periods in names are deleted and only up to the first 8 characters of the word is returned.

### Usage

    first.word(x, i=1, expr=substitute(x))

### Arguments

`x` | any scalar character string
`i` | word number, default value = 1. Used when the second or `i`th word is wanted. Currently only the `i=1` case is implemented.
`expr` | any S object of mode `expression`.

### Value

a character string

### Author(s)

Frank E. Harrell, Jr.,
Department of Biostatistics,
Vanderbilt University,
`f.harrell@vanderbilt.edu`

Richard M. Heiberger,
Department of Statistics,
Temple University, Philadelphia, PA.
`rmh@astro.ocis.temple.edu`

### Examples

    first.word(expr=expression(y ~ x + log(w)))

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