.\"	$OpenBSD: rs.1,v 1.10 2005/05/15 01:36:13 millert Exp $
.\"	$FreeBSD: src/usr.bin/rs/rs.1,v 1.4 1999/08/28 01:05:21 peter Exp $
.\"
.\" Copyright (c) 1993
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.\" modification, are permitted provided that the following conditions
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.\"	@(#)rs.1	8.2 (Berkeley) 12/30/93
.\"
.Dd December 30, 1993
.Dt RS 1
.Os
.Sh NAME
.Nm rs
.Nd reshape a data array
.Sh SYNOPSIS
.Nm rs
.Op Fl CcSs Ns Op Ar x
.Op Fl KkGgw Ar N
.Op Fl EejHhnnTtyz
.Op Ar rows Op Ar cols
.Sh DESCRIPTION
.Nm
reads the standard input, interpreting each line as a row
of blank-separated entries in an array,
transforms the array according to the options,
and writes it on the standard output.
With no arguments it transforms stream input into a columnar
format convenient for terminal viewing.
.Pp
The shape of the input array is deduced from the number of lines
and the number of columns on the first line.
If that shape is inconvenient, a more useful one might be
obtained by skipping some of the input with the
.Fl k
option.
Other options control interpretation of the input columns.
.Pp
The shape of the output array is influenced by the
.Ar rows
and
.Ar cols
specifications, which should be positive integers.
If only one of them is a positive integer,
.Nm
computes a value for the other which will accommodate
all of the data.
When necessary, missing data are supplied in a manner
specified by the options and surplus data are deleted.
There are options to control presentation of the output columns,
including transposition of the rows and columns.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl C Ns Ar x
Output columns are delimited by the single character
.Ar x .
A missing
.Ar x
is taken to be
.Ql ^I .
.It Fl c Ns Ar x
Input columns are delimited by the single character
.Ar x .
A missing
.Ar x
is taken to be
.Ql ^I .
.It Fl E
Consider each character of input as an array entry.
.It Fl e
Consider each line of input as an array entry.
.It Fl G Ns Ar N
The gutter width has
.Ar N
percent of the maximum column width added to it.
.It Fl g Ns Ar N
The gutter width (inter-column space), normally 2, is taken to be
.Ar N .
.It Fl H
Like
.Fl h ,
but also print the length of each line.
.It Fl h
Print the shape of the input array and do nothing else.
The shape is just the number of lines and the number of
entries on the first line.
.It Fl j
Right adjust entries within columns.
.It Fl K Ns Ar N
Like
.Fl k ,
but print the ignored lines.
.It Fl k Ns Ar N
Ignore the first
.Ar N
lines of input.
.It Fl m
Do not trim excess delimiters from the ends of the output array.
.It Fl n
On lines having fewer entries than the first line,
use null entries to pad out the line.
Normally, missing entries are taken from the next line of input.
.It Fl S Ns Ar x
Like
.Fl C ,
but padded strings of
.Ar x
are delimiters.
.It Fl s Ns Ar x
Like
.Fl c ,
but maximal strings of
.Ar x
are delimiters.
.It Fl t
Fill in the rows of the output array using the columns of the
input array, that is, transpose the input while honoring any
.Ar rows
and
.Ar cols
specifications.
.It Fl T
Print the pure transpose of the input, ignoring any
.Ar rows
or
.Ar cols
specification.
.It Fl w Ns Ar N
The width of the display, normally 80, is taken to be the positive
integer
.Ar N .
.It Fl y
If there are too few entries to make up the output dimensions,
pad the output by recycling the input from the beginning.
Normally, the output is padded with blanks.
.It Fl z
Adapt column widths to fit the largest entries appearing in them.
.El
.Pp
With no arguments,
.Nm
transposes its input, and assumes one array entry per input line
unless the first non-ignored line is longer than the display width.
Option letters which take numerical arguments interpret a missing
number as zero unless otherwise indicated.
.Sh EXAMPLES
.Nm
can be used as a filter to convert the stream output
of certain programs (e.g.,
.Xr spell ,
.Xr du ,
.Xr file ,
.Xr look ,
.Xr nm ,
.Xr who ,
and
.Xr wc 1 )
into a convenient
.Dq window
format, as in
.Bd -literal -offset indent
$ who | rs
.Ed
.Pp
This function has been incorporated into the
.Xr ls 1
program, though for most programs with similar output
.Nm
suffices.
.Pp
To convert stream input into vector output and back again, use
.Bd -literal -offset indent
$ rs 1 0 | rs 0 1
.Ed
.Pp
A 10 by 10 array of random numbers from 1 to 100 and
its transpose can be generated with
.Bd -literal -offset indent
$ jot \-r 100 | rs 10 10 | tee array | rs \-T > tarray
.Ed
.Pp
In the editor
.Xr vi 1 ,
a file consisting of a multi-line vector with 9 elements per line
can undergo insertions and deletions,
and then be neatly reshaped into 9 columns with
.Bd -literal -offset indent
:1,$!rs 0 9
.Ed
.Pp
Finally, to sort a database by the first line of each 4-line field, try
.Bd -literal -offset indent
$ rs \-eC 0 4 | sort | rs \-c 0 1
.Ed
.Sh SEE ALSO
.Xr jot 1 ,
.Xr pr 1 ,
.Xr sort 1 ,
.Xr vi 1
.Sh BUGS
Handles only two dimensional arrays.
.Pp
The algorithm currently reads the whole file into memory,
so files that do not fit in memory will not be reshaped.
.Pp
Fields cannot be defined yet on character positions.
.Pp
Re-ordering of columns is not yet possible.
.Pp
There are too many options.