arsort
Dear mike at clear-link dot com!
I needed a case insensitive version of your function. It is still not perfect as I have to do something with country specific characters (öüóőúéáűíÖÜÓŐÚÉÁŰÍ)
function akisort(&$array,$valrev=false,$keyrev=false)
{
if ($valrev)
{
arsort($array);
}
else
{
asort($array);
};
$vals = array_count_values($array);
$i = 0;
foreach ($vals AS $val=>$num)
{
$first = array_splice($array,0,$i);
$tmp = array_splice($array,0,$num);
$tmp2 = array();
foreach($tmp as $key => $value)
{
$tmp2[] = $key;
$number = $value;
};
natcasesort($tmp2);
reset($tmp2);
print_r($tmp2);
unset($tmp);
foreach($tmp2 as $key => $value)
{
$tmp[$value] = $number;
};
if($keyrev)
{
$tmp = array_reverse($tmp, true);
};
$array = array_merge($first,$tmp,$array);
unset($tmp);
$i = $i+$num;
};
};
asort
(PHP 4, PHP 5)
asort — Sort an array and maintain index association
Description
bool asort
( array &$array
[, int $sort_flags
] )
This function sorts an array such that array indices maintain their correlation with the array elements they are associated with. This is used mainly when sorting associative arrays where the actual element order is significant.
Parameters
- array
-
The input array.
- sort_flags
-
You may modify the behavior of the sort using the optional parameter sort_flags , for details see sort().
Return Values
Returns TRUE on success or FALSE on failure.
Examples
Example #1 asort() example
<?php
$fruits = array("d" => "lemon", "a" => "orange", "b" => "banana", "c" => "apple");
asort($fruits);
foreach ($fruits as $key => $val) {
echo "$key = $val\n";
}
?>
The above example will output:
c = apple b = banana d = lemon a = orange
The fruits have been sorted in alphabetical order, and the index associated with each element has been maintained.
add a note
User Contributed Notesasort
bakatamas at freemail dot hu
15-Feb-2008 11:34
15-Feb-2008 11:34
mike at clear-link dot com
01-Feb-2008 12:56
01-Feb-2008 12:56
Small typo in the aksort function I just submitted. Here's the entire thing again, with the correction noted:
<?php
function aksort(&$array,$valrev=false,$keyrev=false) {
if ($valrev) { arsort($array); } else { asort($array); }
$vals = array_count_values($array);
$i = 0;
foreach ($vals AS $val=>$num) {
$first = array_splice($array,0,$i);
$tmp = array_splice($array,0,$num);
if ($keyrev) { krsort($tmp); } else { ksort($tmp); }
$array = array_merge($first,$tmp,$array);
unset($tmp);
$i = $i+$num;
// Fixed from previous post: $i = $num;
}
}
?>
mike at clear-link dot com
01-Feb-2008 12:23
01-Feb-2008 12:23
For a recent project I needed to sort an associative array by value first, and then by key if a particular value appeared multiple times. I wrote this function to accomplish the task. Note that the parameters default to sort ascending on both keys and values, but allow granular control over each.
<?php
function aksort(&$array,$valrev=false,$keyrev=false) {
if ($valrev) { arsort($array); } else { asort($array); }
$vals = array_count_values($array);
$i = 0;
foreach ($vals AS $val=>$num) {
$first = array_splice($array,0,$i);
$tmp = array_splice($array,0,$num);
if ($keyrev) { krsort($tmp); } else { ksort($tmp); }
$array = array_merge($first,$tmp,$array);
unset($tmp);
$i = $num;
}
}
// Example
$tmp = array('ca'=>1,'cb'=>2,'ce'=>1,'pa'=>2,'pe'=>1);
// Standard asort
asort($tmp);
print_r($tmp);
// Sort value ASC, key ASC
aksort($tmp);
print_r($tmp);
// Sort value DESC, key ASC
aksort($tmp,true);
print_r($tmp);
// Sort value DESC, key DESC
aksort($tmp,true,true);
print_r($tmp);
// Results
Array
(
[pe] => 1
[ca] => 1
[ce] => 1
[cb] => 2
[pa] => 2
)
Array
(
[ca] => 1
[ce] => 1
[pe] => 1
[cb] => 2
[pa] => 2
)
Array
(
[cb] => 2
[pa] => 2
[ca] => 1
[ce] => 1
[pe] => 1
)
Array
(
[pa] => 2
[cb] => 2
[pe] => 1
[ce] => 1
[ca] => 1
)
mzvarik at gmail dot com
16-Jan-2008 06:29
16-Jan-2008 06:29
I noticed that my function mentioned earlier is very misleading - somebody please delete that note!
This is how you sort:
<?php
setlocale (LC_ALL, 'czech');
$array = array("a", "č", "c");
usort ($array, 'strcoll');
print_r($array);
?>
mzvarik at gmail dot com
16-Jan-2008 11:46
16-Jan-2008 11:46
I made a sorting function for czech alphabetics, maybe not the most effective function, but it did what I needed.
<?php
function myStrCmp($a, $b)
{
$cz_chars = "Aa Áá Bb Cc Čč Dd Ďď Ee Éé Ěě Ff Gg Hh Ii Íí Jj Kk Ll Mm Nn Ňň Oo Óó Pp Qq Rr Řř Ss Šš Tt Ťť Uu Úú Ůů Vv Ww Xx Yy Ýý Zz Žž";
$cz_ch = 39; // CH
if($a == $b) return 0;
$pos = 0;
$advantage = false;
while(true)
{
if(!isset($a{$pos})) {
$result = !isset($b{$pos}) ? $advantage : -1;
break;
}
elseif(!isset($b{$pos})) {
$result = 1;
break;
}
// A
if(strtolower($a{$pos}) == 'c' && strtolower($a{$pos+1}) == 'h') { // CH
$aa = $cz_ch;
} else {
$aa = strpos($cz_chars, $a{$pos});
}
// B
if(strtolower($b{$pos}) == 'c' && strtolower($b{$pos+1}) == 'h') {
$bb = $cz_ch;
} else {
$bb = strpos($cz_chars, $b{$pos});
}
if($aa === false) return 1;
if($bb === false) return -1;
if($aa != $bb)
{
$diff = $aa-$bb;
if($diff > 1 || $diff < -1) {
$result = $aa > $bb ? -1 : 1;
break;
}
elseif(!$advantage) {
$advantage = $diff == 1 ? -1 : 1;
}
}
$pos++;
}
return $result;
}
function MySort(&$array, $orderby = 'asc')
{
$orderby = $orderby == 'asc' ? 1 : -1;
$keys = array_keys($array);
$values = array_values($array);
$sorted[0] = array_shift($values);
$count = count($values);
foreach($values as $i => $wordA)
{
for($j=0; $j<=$i; $j++) {
if(myStrCmp($wordA, $sorted[$j]) == $orderby) break;
}
array_splice($sorted, $j, 0, array($wordA));
}
$array = array_combine($keys, $sorted);
}
?>
przemekkus [at] interia [dot] pl
02-Nov-2007 03:34
02-Nov-2007 03:34
Function written by a dot brandon at chello dot nl has an error - wrong variable name. It should be:
if($rev) arsort($named_hash,$flags=0) ;
instead of
if($reverse) arsort($named_hash,$flags=0) ;
greenie2600 at yahoo dot com
09-Aug-2007 09:22
09-Aug-2007 09:22
The function offered by richard at happymango dot me dot uk does not handle numeric indices properly. smileaf's suggested fix did not work for me. Use with caution.
a dot brandon at chello dot nl
26-Jun-2007 04:18
26-Jun-2007 04:18
I use this for quasi-SQL orderby. Loosely based on smileaf. Any good for you nerds?
<?
function named_records_sort($named_recs, $order_by, $rev=false, $flags=0)
{// Create 1-dimensional named array with just
// sortfield (in stead of record) values
$named_hash = array();
foreach($named_recs as $key=>$fields)
$named_hash["$key"] = $fields[$order_by];
// Order 1-dimensional array,
// maintaining key-value relations
if($reverse) arsort($named_hash,$flags=0) ;
else asort($named_hash, $flags=0);
// Create copy of named records array
// in order of sortarray
$sorted_records = array();
foreach($named_hash as $key=>$val)
$sorted_records["$key"]= $named_recs[$key];
return $sorted_records;} // named_recs_sort()
function show_sorted_records($named_recs, $order_by, $rev=false, $flags=0)
{$sorted_records=named_records_sort($named_recs, $order_by, $rev, $flags);
foreach($sorted_records as $name=>$fields)
{echo "<b>$name</b> ";
foreach($fields as $field=>$val)
echo "$field = $val "; echo "<br>";}
} // show_sorted_records()
$girl_friends=array();
$girl_friends["Anna"]=
array("born"=>'1989-08-22',"cupsize"=>'B-',"IQ"=>105, "daddy"=>'rich');
$girl_friends["Zoe"]
=array("born"=>'1978-03-11',"cupsize"=>'C#',"IQ"=>130, "daddy"=>'poor');
$girl_friends["Lilly"]
=array("born"=>'1985-06-16',"cupsize"=>'DD',"IQ"=>90, "daddy"=>'nasty');
$order_by="cupsize"; echo "And the winners are: <br>";
show_sorted_records($girl_friends, $order_by, true);
?>
gunnar at taljaren dot se
14-Jun-2007 10:00
14-Jun-2007 10:00
for ($i=0;$i<5;$i++)
$values[] = $i;
asort($values);
works, but
for ($i=0;$i<5;$i++)
$values[$i] =$i;
asort($values);
doesn't!
nilesh dot gamit at gmail dot com
25-Apr-2007 12:50
25-Apr-2007 12:50
function to sort 2d array: recordSort(); It is really helpful as most PHP sort functions provides facility for sorting 1d array & multi dimensional array sorting is not handy. Normally this function will help u.. if u r displaying some records n u want sorting by clicking on some column. basically same is achieved by direct SQL changes like ORDER BY ASC/DESC. But in case, if your records are not actual records, this function will help. i.e. some table has following fields in DB.
name, email, telephone and are_you_married; are_you_married is either 0 / 1. now u r displaying N for 1 and Y for 0; and you want sorting on are_you_married on display. then ORDER BY ASC/DESC. will not work. So, try this…
<?php
function recordSort($records, $field, $reverse, $defaultSortField = 0)
{
$uniqueSortId = 0;
$hash = array(); $sortedRecords = array(); $tempArr = array(); $indexedArray = array(); $recordArray = array();
foreach($records as $record) {
$uniqueSortId++;
$recordStr = implode("|", $record)."|".$uniqueSortId;
$recordArray[] = explode("|", $recordStr);
}
$primarySortIndex = count($record);
$records = $recordArray;
foreach($records as $record) {
$hash[$record[$primarySortIndex]] = $record[$field];
}
uasort($hash, "strnatcasecmp");
if($reverse)
$hash = array_reverse($hash, true);
$valueCount = array_count_values($hash);
foreach($hash as $primaryKey => $value) {
$indexedArray[] = $primaryKey;
}
$i = 0;
foreach($hash as $primaryKey => $value) {
$i++;
if($valueCount[$value] > 1) {
foreach($records as $record) {
if($primaryKey == $record[$primarySortIndex]) {
$tempArr[$record[$defaultSortField]."__".$i] = $record;
break;
}
}
$index = array_search($primaryKey, $indexedArray);
if( ($i == count($records)) || ($value != $hash[$indexedArray[$index+1]]) ) {
uksort($tempArr, "strnatcasecmp");
if($reverse)
$tempArr = array_reverse($tempArr);
foreach($tempArr as $newRecs) {
$sortedRecords [] = $newRecs;
}
$tempArr = array();
}
}
else {
foreach($records as $record) {
if($primaryKey == $record[$primarySortIndex]) {
$sortedRecords[] = $record;
break;
}
}
}
}
return $sortedRecords;
}
$array[0][0] = 'nilesh'; // sort_index = 0
$array[0][1] = 'yogesh'; // sort_index = 1
$array[0][2] = 'aakash'; // sort_index = 2
$array[0][3] = '100'; // sort_index = 3
$array[0][4] = 'nilesh'; // sort_index = 4
$array[0][5] = 'Nil100'; // sort_index = 5
$array[0][6] = 'Y'; // sort_index = 6
$array[1][0] = 'Nil100';
$array[1][1] = '1001';
$array[1][2] = 'nilesh';
$array[1][3] = 'nilesh';
$array[1][4] = 'nilesh';
$array[1][5] = 'yogesh';
$array[1][6] = 'Nil100';
$array[2][0] = 'Nil100';
$array[2][1] = 'Y';
$array[2][2] = '100';
$array[2][3] = '10nilesh';
$array[2][4] = 'aakash';
$array[2][5] = '_aakash';
$array[2][6] = 'aakash_';
echo "array before sorting..."
print_r($array);
/* $sortedList = recordSort(2d_array, sort_index, reverse, second_level_sort_index_if_duplicates_found_default_is_0 = '0'); */
$sortedList = recordSort($array, 4, 0, 5);
echo "array after sorting..."
print_r($sortedList);
?>
smileaf at smileaf dot org
25-Jan-2007 03:34
25-Jan-2007 03:34
Ok I was mistaken, after re-reading the previous post the ".$key" is important. What caused the sorting issue for me wasn't that at all. But rather something else.
doing an: asort($records, $flags); before returning fixes the sorting problems.
The sorting problem I was refearing to causes a character based sorting done on numeric data.
so instead of:
1
2
3
...
10
12
20
It was returned back as
1
10
12
2
20
3
...
basically what I was trying to fix in the first place.
smileaf at smileaf dot org
25-Jan-2007 01:59
25-Jan-2007 01:59
This revised version removes the ".$key" from the hash as I wasn't sure why it was there and caused sorting problems for me.
And allows the use of the array flags in both ksort and krsort.
<?
function record_sort($records, $field, $reverse=false, $flags=0)
{
$hash = array();
foreach($records as $key => $record)
{
$hash[$record[$field]] = $record;
}
($reverse)? krsort($hash, $flags) : ksort($hash, $flags);
$records = array();
foreach($hash as $record)
{
$records []= $record;
}
return $records;
}
?>
richard at happymango dot me dot uk
23-Nov-2006 12:52
23-Nov-2006 12:52
This is a fixed version of the same function I posted below. Now it will handle duplicate entries in the sorted field. EG: If there were two records that had the name Heathrow it would still work.
<?php
function record_sort($records, $field, $reverse=false)
{
$hash = array();
foreach($records as $key => $record)
{
$hash[$record[$field].$key] = $record;
}
($reverse)? krsort($hash) : ksort($hash);
$records = array();
foreach($hash as $record)
{
$records []= $record;
}
return $records;
}
?>
richard at happymango dot me dot uk
22-Nov-2006 12:35
22-Nov-2006 12:35
This is a function to sort an indexed 2D array by a specified sub array key, either ascending or descending.
It is usefull for sorting query results from a database by a particular field after the query has been returned
This function can be quite greedy. It recreates the array as a hash to use ksort() then back again
By default it will sort ascending but if you specify $reverse as true it will return the records sorted descending
<?php
function record_sort($records, $field, $reverse=false)
{
$hash = array();
foreach($records as $record)
{
$hash[$record[$field]] = $record;
}
($reverse)? krsort($hash) : ksort($hash);
$records = array();
foreach($hash as $record)
{
$records []= $record;
}
return $records;
}
// Example below
$airports = array
(
array( "code" => "LHR", "name" => "Heathrow" ),
array( "code" => "LGW", "name" => "Gatwick" ),
);
printf("Before: <pre>%s</pre>", print_r($airports, true));
$airports = record_sort($airports, "name");
printf("After: <pre>%s</pre>", print_r($airports, true));
?>
Example Outputs:
Before: Array
(
[0] => Array ( [code] => LHR, [name] => Heathrow )
[1] => Array ( [code] => LGW, [name] => Gatwick )
)
After: Array
(
[0] => Array ( [code] => LGW, [name] => Gatwick )
[1] => Array ( [code] => LHR, [name] => Heathrow )
)
php at web-in-time dot com
05-Sep-2006 11:47
05-Sep-2006 11:47
acecream's function works fine, especially with the spectre extension.
nevertheless sometimes the index values have to be kept. To achieve this, just replace:
$sorted_arr[] = $array[$arr_key];
with:
$sorted_arr[$arr_key] = $array[$arr_key];
rojaro
24-Jun-2004 04:38
24-Jun-2004 04:38
Advanced sort array by second index function, which produces ascending (default) or descending output and uses optionally natural case insensitive sorting (which can be optionally case sensitive as well).
Only the first two arguments are required.
<?php
function sabsi ($array, $index, $order='asc', $natsort=FALSE, $case_sensitive=FALSE) {
if(is_array($array) && count($array)>0) {
foreach(array_keys($array) as $key) $temp[$key]=$array[$key][$index];
if(!$natsort) ($order=='asc')? asort($temp) : arsort($temp);
else {
($case_sensitive)? natsort($temp) : natcasesort($temp);
if($order!='asc') $temp=array_reverse($temp,TRUE);
}
foreach(array_keys($temp) as $key) (is_numeric($key))? $sorted[]=$array[$key] : $sorted[$key]=$array[$key];
return $sorted;
}
return $array;
}
?>
csaba at alum dot mit dot edu
23-Jun-2004 01:47
23-Jun-2004 01:47
If you have a pair of arrays which have a one to one association (examples: spouses, first to last name, SSN to name), when you sort one, you might wish to sort the other in the same way to maintain the correlation. This example illustrates a way:
<?php
$aMen = array('Fred', 'Bob', 'Tim', 'John', 'Bill');
$aPartner = array('Sue', 'Mary', 'Ann', 'Cathy', 'Nancy');
asort($aMen); // aMen now sorted; numeric keys out of order
$aWomen = array_keys($aMen); // create a new array for result
foreach ($aWomen as $idx => &$name) $name=$aPartner[$name];
// aWomen now has the sorted partners
$aMen = array_merge($aMen); // put the numeric keys in order
?>
Csaba Gabor
KOmaSHOOTER at gmx dot de
21-May-2003 02:52
21-May-2003 02:52
here another version from acecream multisorting for arrays :)
<?php
function array_sort_multi2($array, $key,$key2)
{
for ($i = 0; $i < sizeof($array); $i++) {
if(! empty($array[$i][$key][$key2])){
$sort_values[$i] = $array[$i][$key][$key2];
}else{
$sort_values[$i] = $array[$i];
}
}
asort ($sort_values);
reset ($sort_values);
while (list ($arr_keys, $arr_values) = each ($sort_values)) {
$sorted_arr[] = $array[$arr_keys];
}
return $sorted_arr;
}
?>
spectre at hellfish dot NOSPAM dot org
28-Apr-2003 06:54
28-Apr-2003 06:54
that works nicely, tho it breaks the result-array up if one or more of arrays indexes are deleted before sorting. this one should fix it up:
change:
for ($i = 0; $i < sizeof($array); $i++) {
to:
foreach ($array as $i => $k) {
acecream
23-Apr-2003 01:02
23-Apr-2003 01:02
my version of sorting multi dimensional array
<?php
function array_sort($array, $key)
{
for ($i = 0; $i < sizeof($array); $i++) {
$sort_values[$i] = $array[$i][$key];
}
asort ($sort_values);
reset ($sort_values);
while (list ($arr_key, $arr_val) = each ($sort_values)) {
$sorted_arr[] = $array[$arr_key];
}
return $sorted_arr;
}
?>
mbevan at marginsoftware dot com
03-Dec-2002 10:25
03-Dec-2002 10:25
Nevermind... use my last note as a quick tip: if you wish to keep the keys, use asort() and arsort() in place of sort() and rsort().
01-Aug-2002 03:48
Sorry, my last post had a typo:
// unnecessary backslashes break create_function, oops.
if ( is_string($var) ) $var = "\'$var\'";
//it should be:
if ( is_string($var) ) $var = "'$var'";
-- FIXED and TESTED -- :)
Similar to above but for an array of arrays instead of an array of objects.
<?php
function aasort($x,$var,$cmp='strcasecmp'){
if ( is_string($var) ) $var = "'$var'";
uasort($x,
create_function('$a,$b',
'return '.$cmp.'( $a['.$var.'],$b['.$var.']);')
);
return $x;
}
?>
phzzzt .a.t. acm .d.o.t. org
01-Aug-2002 03:32
01-Aug-2002 03:32
Similar to above but for an array of arrays instead of an array of objects.
<?php
function aasort($x,$var,$cmp='strcasecmp'){
if ( is_string($var) ) $var = "\'$var\'";
uasort($x,
create_function('$a,$b',
'return '.$cmp.'( $a['.$var.'],$b['.$var.']);')
);
return $x;
}
?>
salchicha at cable dot net dot co
03-Apr-2002 11:23
03-Apr-2002 11:23
Here's one I whipped up to allow you to sort an array of a specific class by a member or function:
<?php
// Sort a class by one of its members (even lowercase!!!)
function casort($arr, $var) {
$tarr = array();
$rarr = array();
for($i = 0; $i < count($arr); $i++) {
$element = $arr[$i];
$tarr[] = strtolower($element->{$var});
}
reset($tarr);
asort($tarr);
$karr = array_keys($tarr);
for($i = 0; $i < count($tarr); $i++) {
$rarr[] = $arr[intval($karr[$i])];
}
return $rarr;
}
?>
It works very well. For example, I have a Room class with members title, isActive(), date, etc. I can sort an array by casort($rooms, "title") or casort($rooms, "isActive()") and it'll work.
rcwang at cmu dot edu
03-Mar-2002 02:42
03-Mar-2002 02:42
Here's my version of sorting multi-dimensional array by 2nd index.
Feel free to change the code to suit your needs.
<?php
function aSortBySecondIndex($multiArray, $secondIndex) {
while (list($firstIndex, ) = each($multiArray))
$indexMap[$firstIndex] = $multiArray[$firstIndex][$secondIndex];
asort($indexMap);
while (list($firstIndex, ) = each($indexMap))
if (is_numeric($firstIndex))
$sortedArray[] = $multiArray[$firstIndex];
else $sortedArray[$firstIndex] = $multiArray[$firstIndex];
return $sortedArray;
}
?>
markus at runout dot at
29-Nov-2001 09:37
29-Nov-2001 09:37
for sorting CASEINSENSITIVE try
natcasesort()
there's little difference to sort,
but maybe that doesn't matter for you.
freeman at generalresources dot com
04-May-2001 01:51
04-May-2001 01:51
The asortbyindex($sortarray, $index) looks like sort not asort. The key of the $sortarray was changed.
sweetland at whoadammit dot com
15-Aug-2000 09:02
15-Aug-2000 09:02
Here's a little routine I whipped up to sort multi-dimensional arrays:
<?php
/**
** comesafter ($s1, $s2)
**
** Returns 1 if $s1 comes after $s2 alphabetically, 0 if not.
**/
function comesafter ($s1, $s2) {
/**
** We don't want to overstep the bounds of one of the strings and segfault,
** so let's see which one is shorter.
**/
$order = 1;
if (strlen ($s1) > strlen ($s2)) {
$temp = $s1;
$s1 = $s2;
$s2 = $temp;
$order = 0;
}
for ($index = 0; $index < strlen ($s1); $index++) {
/**
** $s1 comes after $s2
**/
if ($s1[$index] > $s2[$index]) return ($order);
/**
** $s1 comes before $s2
**/
if ($s1[$index] < $s2[$index]) return (1 - $order);
}
/**
** Special case in which $s1 is a substring of $s2
**/
return ($order);
}
/**
** asortbyindex ($sortarray, $index)
**
** Sort a multi-dimensional array by a second-degree index. For instance, the 0th index
** of the Ith member of both the group and user arrays is a string identifier. In the
** case of a user array this is the username; with the group array it is the group name.
** asortby
**/
function asortbyindex ($sortarray, $index) {
$lastindex = count ($sortarray) - 1;
for ($subindex = 0; $subindex < $lastindex; $subindex++) {
$lastiteration = $lastindex - $subindex;
for ($iteration = 0; $iteration < $lastiteration; $iteration++) {
$nextchar = 0;
if (comesafter ($sortarray[$iteration][$index], $sortarray[$iteration + 1][$index])) {
$temp = $sortarray[$iteration];
$sortarray[$iteration] = $sortarray[$iteration + 1];
$sortarray[$iteration + 1] = $temp;
}
}
}
return ($sortarray);
}
?>
It's a bit long with all the comments, but I hope it helps.
bwuhlman at tallships dot ca
03-Aug-2000 12:01
03-Aug-2000 12:01
Well, actually, asort has *two* annoying features.
It works perfectly well sorting hashes (or associative arrays, as you might have it), but doggedly refuses to sort regular arrays maintaining index assocation. Kind've makes sense, but the docs don't explicitly say you can't do it.
Urgggh.
jacko at kring dot co dot uk
25-Feb-2000 08:26
25-Feb-2000 08:26
asort has one anoying feature, it ignores any default or implicit order in the data. i.e. if two elements of an array contain "banana" then it is not garanteed that the first will still be the first after the sort.
This makes the Burrows-Wheeler block sort a bit of a pain to impliment, with a trailing string having to be appended to all strings before sorting, and removed after sorting. To maintain the so called "banana" order.