'\"
'\" Copyright (c) 1993 The Regents of the University of California.
'\" Copyright (c) 1994-1996 Sun Microsystems, Inc.
'\" Copyright (c) 1999 Scriptics Corporation
'\" Copyright (c) 2001 Kevin B. Kenny.  All rights reserved.
'\"
'\" See the file "license.terms" for information on usage and redistribution
'\" of this file, and for a DISCLAIMER OF ALL WARRANTIES.
'\" 
'\" RCS: @(#) $Id: lsort.n,v 1.12.4.1 2003/03/17 14:25:20 dkf Exp $
'\" 
'\" The definitions below are for supplemental macros used in Tcl/Tk
'\" manual entries.
'\"
'\" .AP type name in/out ?indent?
'\"	Start paragraph describing an argument to a library procedure.
'\"	type is type of argument (int, etc.), in/out is either "in", "out",
'\"	or "in/out" to describe whether procedure reads or modifies arg,
'\"	and indent is equivalent to second arg of .IP (shouldn't ever be
'\"	needed;  use .AS below instead)
'\"
'\" .AS ?type? ?name?
'\"	Give maximum sizes of arguments for setting tab stops.  Type and
'\"	name are examples of largest possible arguments that will be passed
'\"	to .AP later.  If args are omitted, default tab stops are used.
'\"
'\" .BS
'\"	Start box enclosure.  From here until next .BE, everything will be
'\"	enclosed in one large box.
'\"
'\" .BE
'\"	End of box enclosure.
'\"
'\" .CS
'\"	Begin code excerpt.
'\"
'\" .CE
'\"	End code excerpt.
'\"
'\" .VS ?version? ?br?
'\"	Begin vertical sidebar, for use in marking newly-changed parts
'\"	of man pages.  The first argument is ignored and used for recording
'\"	the version when the .VS was added, so that the sidebars can be
'\"	found and removed when they reach a certain age.  If another argument
'\"	is present, then a line break is forced before starting the sidebar.
'\"
'\" .VE
'\"	End of vertical sidebar.
'\"
'\" .DS
'\"	Begin an indented unfilled display.
'\"
'\" .DE
'\"	End of indented unfilled display.
'\"
'\" .SO
'\"	Start of list of standard options for a Tk widget.  The
'\"	options follow on successive lines, in four columns separated
'\"	by tabs.
'\"
'\" .SE
'\"	End of list of standard options for a Tk widget.
'\"
'\" .OP cmdName dbName dbClass
'\"	Start of description of a specific option.  cmdName gives the
'\"	option's name as specified in the class command, dbName gives
'\"	the option's name in the option database, and dbClass gives
'\"	the option's class in the option database.
'\"
'\" .UL arg1 arg2
'\"	Print arg1 underlined, then print arg2 normally.
'\"
'\" RCS: @(#) $Id: man.macros,v 1.4 2000/08/25 06:18:32 ericm Exp $
'\"
'\"	# Set up traps and other miscellaneous stuff for Tcl/Tk man pages.
.if t .wh -1.3i ^B
.nr ^l \n(.l
.ad b
'\"	# Start an argument description
.de AP
.ie !"\\$4"" .TP \\$4
.el \{\
.   ie !"\\$2"" .TP \\n()Cu
.   el          .TP 15
.\}
.ta \\n()Au \\n()Bu
.ie !"\\$3"" \{\
\&\\$1	\\fI\\$2\\fP	(\\$3)
.\".b
.\}
.el \{\
.br
.ie !"\\$2"" \{\
\&\\$1	\\fI\\$2\\fP
.\}
.el \{\
\&\\fI\\$1\\fP
.\}
.\}
..
'\"	# define tabbing values for .AP
.de AS
.nr )A 10n
.if !"\\$1"" .nr )A \\w'\\$1'u+3n
.nr )B \\n()Au+15n
.\"
.if !"\\$2"" .nr )B \\w'\\$2'u+\\n()Au+3n
.nr )C \\n()Bu+\\w'(in/out)'u+2n
..
.AS Tcl_Interp Tcl_CreateInterp in/out
'\"	# BS - start boxed text
'\"	# ^y = starting y location
'\"	# ^b = 1
.de BS
.br
.mk ^y
.nr ^b 1u
.if n .nf
.if n .ti 0
.if n \l'\\n(.lu\(ul'
.if n .fi
..
'\"	# BE - end boxed text (draw box now)
.de BE
.nf
.ti 0
.mk ^t
.ie n \l'\\n(^lu\(ul'
.el \{\
.\"	Draw four-sided box normally, but don't draw top of
.\"	box if the box started on an earlier page.
.ie !\\n(^b-1 \{\
\h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.el \}\
\h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\l'|0u-1.5n\(ul'
.\}
.\}
.fi
.br
.nr ^b 0
..
'\"	# VS - start vertical sidebar
'\"	# ^Y = starting y location
'\"	# ^v = 1 (for troff;  for nroff this doesn't matter)
.de VS
.if !"\\$2"" .br
.mk ^Y
.ie n 'mc \s12\(br\s0
.el .nr ^v 1u
..
'\"	# VE - end of vertical sidebar
.de VE
.ie n 'mc
.el \{\
.ev 2
.nf
.ti 0
.mk ^t
\h'|\\n(^lu+3n'\L'|\\n(^Yu-1v\(bv'\v'\\n(^tu+1v-\\n(^Yu'\h'-|\\n(^lu+3n'
.sp -1
.fi
.ev
.\}
.nr ^v 0
..
'\"	# Special macro to handle page bottom:  finish off current
'\"	# box/sidebar if in box/sidebar mode, then invoked standard
'\"	# page bottom macro.
.de ^B
.ev 2
'ti 0
'nf
.mk ^t
.if \\n(^b \{\
.\"	Draw three-sided box if this is the box's first page,
.\"	draw two sides but no top otherwise.
.ie !\\n(^b-1 \h'-1.5n'\L'|\\n(^yu-1v'\l'\\n(^lu+3n\(ul'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.el \h'-1.5n'\L'|\\n(^yu-1v'\h'\\n(^lu+3n'\L'\\n(^tu+1v-\\n(^yu'\h'|0u'\c
.\}
.if \\n(^v \{\
.nr ^x \\n(^tu+1v-\\n(^Yu
\kx\h'-\\nxu'\h'|\\n(^lu+3n'\ky\L'-\\n(^xu'\v'\\n(^xu'\h'|0u'\c
.\}
.bp
'fi
.ev
.if \\n(^b \{\
.mk ^y
.nr ^b 2
.\}
.if \\n(^v \{\
.mk ^Y
.\}
..
'\"	# DS - begin display
.de DS
.RS
.nf
.sp
..
'\"	# DE - end display
.de DE
.fi
.RE
.sp
..
'\"	# SO - start of list of standard options
.de SO
.SH "STANDARD OPTIONS"
.LP
.nf
.ta 5.5c 11c
.ft B
..
'\"	# SE - end of list of standard options
.de SE
.fi
.ft R
.LP
See the \\fBoptions\\fR manual entry for details on the standard options.
..
'\"	# OP - start of full description for a single option
.de OP
.LP
.nf
.ta 4c
Command-Line Name:	\\fB\\$1\\fR
Database Name:	\\fB\\$2\\fR
Database Class:	\\fB\\$3\\fR
.fi
.IP
..
'\"	# CS - begin code excerpt
.de CS
.RS
.nf
.ta .25i .5i .75i 1i
..
'\"	# CE - end code excerpt
.de CE
.fi
.RE
..
.de UL
\\$1\l'|0\(ul'\\$2
..
.TH lsort n 8.3 Tcl "Tcl Built-In Commands"
.BS
'\" Note:  do not modify the .SH NAME line immediately below!
.SH NAME
lsort \- Sort the elements of a list
.SH SYNOPSIS
\fBlsort \fR?\fIoptions\fR? \fIlist\fR
.BE

.SH DESCRIPTION
.PP
This command sorts the elements of \fIlist\fR, returning a new
list in sorted order.  The implementation of the \fBlsort\fR command
uses the merge\-sort algorithm which is a stable sort that has O(n log
n) performance characteristics.
.PP
By default ASCII sorting is used with the result returned in
increasing order.  However, any of the following options may be
specified before \fIlist\fR to control the sorting process (unique
abbreviations are accepted):
.TP 20
\fB\-ascii\fR
Use string comparison with Unicode code-point collation order (the
name is for backward-compatability reasons.)  This is the default.
.TP 20
\fB\-dictionary\fR
Use dictionary-style comparison.  This is the same as \fB\-ascii\fR
except (a) case is ignored except as a tie-breaker and (b) if two
strings contain embedded numbers, the numbers compare as integers,
not characters.  For example, in \fB\-dictionary\fR mode, \fBbigBoy\fR
sorts between \fBbigbang\fR and \fBbigboy\fR, and \fBx10y\fR
sorts between \fBx9y\fR and \fBx11y\fR.
.TP 20
\fB\-integer\fR
Convert list elements to integers and use integer comparison.
.TP 20
\fB\-real\fR
Convert list elements to floating-point values and use floating comparison.
.TP 20
\fB\-command\0\fIcommand\fR
Use \fIcommand\fR as a comparison command.
To compare two elements, evaluate a Tcl script consisting of
\fIcommand\fR with the two elements appended as additional
arguments.  The script should return an integer less than,
equal to, or greater than zero if the first element is to
be considered less than, equal to, or greater than the second,
respectively.
.TP 20
\fB\-increasing\fR
Sort the list in increasing order (``smallest'' items first).
This is the default.
.TP 20
\fB\-decreasing\fR
Sort the list in decreasing order (``largest'' items first).
.TP 20
\fB\-index\0\fIindex\fR
If this option is specified, each of the elements of \fIlist\fR must
itself be a proper Tcl sublist.  Instead of sorting based on whole
sublists, \fBlsort\fR will extract the \fIindex\fR'th element from
each sublist and sort based on the given element.  The keyword
\fBend\fP is allowed for the \fIindex\fP to sort on the last sublist
element,
.VS 8.4
and \fBend-\fIindex\fR sorts on a sublist element offset from
the end.
.VE
For example,
.RS
.CS
lsort -integer -index 1 {{First 24} {Second 18} {Third 30}}
.CE
returns \fB{Second 18} {First 24} {Third 30}\fR, and
.VS 8.4
'\"
'\" This example is from the test suite!
'\"
.CS
lsort -index end-1 {{a 1 e i} {b 2 3 f g} {c 4 5 6 d h}}
.CE
returns \fB{c 4 5 6 d h} {a 1 e i} {b 2 3 f g}\fR.
.VE
This option is much more efficient than using \fB\-command\fR
to achieve the same effect.
.RE
.TP 20
\fB\-unique\fR
If this option is specified, then only the last set of duplicate
elements found in the list will be retained.  Note that duplicates are
determined relative to the comparison used in the sort.  Thus if 
\fI-index 0\fR is used, \fB{1 a}\fR and \fB{1 b}\fR would be
considered duplicates and only the second element, \fB{1 b}\fR, would
be retained.

.SH "NOTES"
.PP
The options to \fBlsort\fR only control what sort of comparison is
used, and do not necessarily constrain what the values themselves
actually are.  This distinction is only noticeable when the list to be
sorted has fewer than two elements.
.PP
The \fBlsort\fR command is reentrant, meaning it is safe to use as
part of the implementation of a command used in the \fB\-command\fR
option.

.SH "EXAMPLES"

.PP
Sorting a list using ASCII sorting:
.CS
% lsort {a10 B2 b1 a1 a2}
B2 a1 a10 a2 b1
.CE

.PP
Sorting a list using Dictionary sorting:
.CS
% lsort -dictionary {a10 B2 b1 a1 a2}
a1 a2 a10 b1 B2
.CE

.PP
Sorting lists of integers:
.CS
% lsort -integer {5 3 1 2 11 4}
1 2 3 4 5 11
% lsort -integer {1 2 0x5 7 0 4 -1}
-1 0 1 2 4 0x5 7
.CE

.PP
Sorting lists of floating-point numbers:
.CS
% lsort -real {5 3 1 2 11 4}
1 2 3 4 5 11
% lsort -real {.5 0.07e1 0.4 6e-1}
0.4 .5 6e-1 0.07e1
.CE

.PP
Sorting using indices:
.CS
% # Note the space character before the c
% lsort {{a 5} { c 3} {b 4} {e 1} {d 2}}
{ c 3} {a 5} {b 4} {d 2} {e 1}
% lsort -index 0 {{a 5} { c 3} {b 4} {e 1} {d 2}}
{a 5} {b 4} { c 3} {d 2} {e 1}
% lsort -index 1 {{a 5} { c 3} {b 4} {e 1} {d 2}}
{e 1} {d 2} { c 3} {b 4} {a 5}
.CE

.PP
Stripping duplicate values using sorting:
.CS
% lsort -unique {a b c a b c a b c}
a b c
.CE

.PP
More complex sorting using a comparison function:
.CS
% proc compare {a b} {
    set a0 [lindex $a 0]
    set b0 [lindex $b 0]
    if {$a0 < $b0} {
        return -1
    } elseif {$a0 > $b0} {
        return 1
    }
    return [string compare [lindex $a 1] [lindex $b 1]]
}
% lsort -command compare \\
        {{3 apple} {0x2 carrot} {1 dingo} {2 banana}}
{1 dingo} {2 banana} {0x2 carrot} {3 apple}
.CE

.SH "SEE ALSO"
.VS 8.4
list(n), lappend(n), lindex(n), linsert(n), llength(n), lsearch(n), 
lset(n), lrange(n), lreplace(n)
.VE

.SH KEYWORDS
element, list, order, sort
