Mixing
Sorting algorithm gone wrong
0
im trying to translate a sortingmethod from Javascript to php and i have run in to some trouble.
The code looks as follows:
private static function quicksort($ids, $dists, $left, $right) {
if ($right - $left <= 20) {
for ($i = $left + 1; $i <= $right; $i++) {
$temp = $ids[$i];
$tempDist = $dists[$temp];
$j = $i - 1;
while ($j >= $left && $dists[$ids[$j]] > $tempDist) {
$ids[$j + 1] = $ids[$j--];
}
$ids[$j + 1] = $temp;
}
} else {
$median = ($left + $right) >> 1;
$i = $left + 1;
$j = $right;
self::swap($ids, $median, $i);
if ($dists[$ids[$left]] > $dists[$ids[$right]]) self::swap($ids, $left, $right);
if ($dists[$ids[$i]] > $dists[$ids[$right]]) self::swap($ids, $i, $right);
if ($dists[$ids[$left]] > $dists[$ids[$i]]) self::swap($ids, $left, $i);
$temp = $ids[$i];
$tempDist = $dists[$temp];
while (true) {
do $i++; while ($dists[$ids[$i]] < $tempDist);
do $j--; while ($dists[$ids[$j]] > $tempDist);
if ($j < $i) break;
self::swap($ids, $i, $j);
}
$ids[$left + 1] = $ids[$j];
$ids[$j] = $temp;
if ($right - $i + 1 >= $j - $left) {
self::quicksort($ids, $dists, $i, $right);
self::quicksort($ids, $dists, $left, $j - 1);
} else {
self::quicksort($ids, $dists, $left, $j - 1);
self::quicksort($ids, $dists, $i, $right);
}
}
}
private static function swap($arr, $i, $j) {
$tmp = $arr[$i];
$arr[$i] = $arr[$j];
$arr[$j] = $tmp;
}
I run this code with these parameters:
- $ids - array with 80 objects
- $dists - array with 80 objects
- $left - 0
- $right - 79
and get an error on this line saying Undefined offset: 161
do $i++; while ($dists[$ids[$i]] < $tempDist);
php
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
|
show 1 more comment
0
im trying to translate a sortingmethod from Javascript to php and i have run in to some trouble.
The code looks as follows:
private static function quicksort($ids, $dists, $left, $right) {
if ($right - $left <= 20) {
for ($i = $left + 1; $i <= $right; $i++) {
$temp = $ids[$i];
$tempDist = $dists[$temp];
$j = $i - 1;
while ($j >= $left && $dists[$ids[$j]] > $tempDist) {
$ids[$j + 1] = $ids[$j--];
}
$ids[$j + 1] = $temp;
}
} else {
$median = ($left + $right) >> 1;
$i = $left + 1;
$j = $right;
self::swap($ids, $median, $i);
if ($dists[$ids[$left]] > $dists[$ids[$right]]) self::swap($ids, $left, $right);
if ($dists[$ids[$i]] > $dists[$ids[$right]]) self::swap($ids, $i, $right);
if ($dists[$ids[$left]] > $dists[$ids[$i]]) self::swap($ids, $left, $i);
$temp = $ids[$i];
$tempDist = $dists[$temp];
while (true) {
do $i++; while ($dists[$ids[$i]] < $tempDist);
do $j--; while ($dists[$ids[$j]] > $tempDist);
if ($j < $i) break;
self::swap($ids, $i, $j);
}
$ids[$left + 1] = $ids[$j];
$ids[$j] = $temp;
if ($right - $i + 1 >= $j - $left) {
self::quicksort($ids, $dists, $i, $right);
self::quicksort($ids, $dists, $left, $j - 1);
} else {
self::quicksort($ids, $dists, $left, $j - 1);
self::quicksort($ids, $dists, $i, $right);
}
}
}
private static function swap($arr, $i, $j) {
$tmp = $arr[$i];
$arr[$i] = $arr[$j];
$arr[$j] = $tmp;
}
I run this code with these parameters:
- $ids - array with 80 objects
- $dists - array with 80 objects
- $left - 0
- $right - 79
and get an error on this line saying Undefined offset: 161
do $i++; while ($dists[$ids[$i]] < $tempDist);
php
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
3
Are you doing this as an exercise? If not, you should just usesort()
– Karsten Koop
Nov 20 '18 at 11:03
I'm trying to translate a sortingmethod from Javascript to php... Why?
– B001ᛦ
Nov 20 '18 at 11:19
JavaScript allows accessing of non-existent array elements or string positions, and will just returnundefinedwithout issuing any warning or error; PHP however does not, and gives you an “undefined index/offset” in such a case. So you need to test whether what you want to access exists first.
– misorude
Nov 20 '18 at 11:41
@KarstenKoop: No but it is a part of a larger library that i am translating so i want it to be the same method.
– Pei-turn
Nov 20 '18 at 12:13
@B001ᛦ: because i need the code to run serverside and i dont have node.js
– Pei-turn
Nov 20 '18 at 12:18
|
show 1 more comment
0
0
0
im trying to translate a sortingmethod from Javascript to php and i have run in to some trouble.
The code looks as follows:
private static function quicksort($ids, $dists, $left, $right) {
if ($right - $left <= 20) {
for ($i = $left + 1; $i <= $right; $i++) {
$temp = $ids[$i];
$tempDist = $dists[$temp];
$j = $i - 1;
while ($j >= $left && $dists[$ids[$j]] > $tempDist) {
$ids[$j + 1] = $ids[$j--];
}
$ids[$j + 1] = $temp;
}
} else {
$median = ($left + $right) >> 1;
$i = $left + 1;
$j = $right;
self::swap($ids, $median, $i);
if ($dists[$ids[$left]] > $dists[$ids[$right]]) self::swap($ids, $left, $right);
if ($dists[$ids[$i]] > $dists[$ids[$right]]) self::swap($ids, $i, $right);
if ($dists[$ids[$left]] > $dists[$ids[$i]]) self::swap($ids, $left, $i);
$temp = $ids[$i];
$tempDist = $dists[$temp];
while (true) {
do $i++; while ($dists[$ids[$i]] < $tempDist);
do $j--; while ($dists[$ids[$j]] > $tempDist);
if ($j < $i) break;
self::swap($ids, $i, $j);
}
$ids[$left + 1] = $ids[$j];
$ids[$j] = $temp;
if ($right - $i + 1 >= $j - $left) {
self::quicksort($ids, $dists, $i, $right);
self::quicksort($ids, $dists, $left, $j - 1);
} else {
self::quicksort($ids, $dists, $left, $j - 1);
self::quicksort($ids, $dists, $i, $right);
}
}
}
private static function swap($arr, $i, $j) {
$tmp = $arr[$i];
$arr[$i] = $arr[$j];
$arr[$j] = $tmp;
}
I run this code with these parameters:
- $ids - array with 80 objects
- $dists - array with 80 objects
- $left - 0
- $right - 79
and get an error on this line saying Undefined offset: 161
do $i++; while ($dists[$ids[$i]] < $tempDist);
php
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
im trying to translate a sortingmethod from Javascript to php and i have run in to some trouble.
The code looks as follows:
private static function quicksort($ids, $dists, $left, $right) {
if ($right - $left <= 20) {
for ($i = $left + 1; $i <= $right; $i++) {
$temp = $ids[$i];
$tempDist = $dists[$temp];
$j = $i - 1;
while ($j >= $left && $dists[$ids[$j]] > $tempDist) {
$ids[$j + 1] = $ids[$j--];
}
$ids[$j + 1] = $temp;
}
} else {
$median = ($left + $right) >> 1;
$i = $left + 1;
$j = $right;
self::swap($ids, $median, $i);
if ($dists[$ids[$left]] > $dists[$ids[$right]]) self::swap($ids, $left, $right);
if ($dists[$ids[$i]] > $dists[$ids[$right]]) self::swap($ids, $i, $right);
if ($dists[$ids[$left]] > $dists[$ids[$i]]) self::swap($ids, $left, $i);
$temp = $ids[$i];
$tempDist = $dists[$temp];
while (true) {
do $i++; while ($dists[$ids[$i]] < $tempDist);
do $j--; while ($dists[$ids[$j]] > $tempDist);
if ($j < $i) break;
self::swap($ids, $i, $j);
}
$ids[$left + 1] = $ids[$j];
$ids[$j] = $temp;
if ($right - $i + 1 >= $j - $left) {
self::quicksort($ids, $dists, $i, $right);
self::quicksort($ids, $dists, $left, $j - 1);
} else {
self::quicksort($ids, $dists, $left, $j - 1);
self::quicksort($ids, $dists, $i, $right);
}
}
}
private static function swap($arr, $i, $j) {
$tmp = $arr[$i];
$arr[$i] = $arr[$j];
$arr[$j] = $tmp;
}
I run this code with these parameters:
- $ids - array with 80 objects
- $dists - array with 80 objects
- $left - 0
- $right - 79
and get an error on this line saying Undefined offset: 161
do $i++; while ($dists[$ids[$i]] < $tempDist);
php
php
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
asked Nov 20 '18 at 11:00
Pei-turnPei-turn
177
177
3
Are you doing this as an exercise? If not, you should just usesort()
– Karsten Koop
Nov 20 '18 at 11:03
I'm trying to translate a sortingmethod from Javascript to php... Why?
– B001ᛦ
Nov 20 '18 at 11:19
JavaScript allows accessing of non-existent array elements or string positions, and will just returnundefinedwithout issuing any warning or error; PHP however does not, and gives you an “undefined index/offset” in such a case. So you need to test whether what you want to access exists first.
– misorude
Nov 20 '18 at 11:41
@KarstenKoop: No but it is a part of a larger library that i am translating so i want it to be the same method.
– Pei-turn
Nov 20 '18 at 12:13
@B001ᛦ: because i need the code to run serverside and i dont have node.js
– Pei-turn
Nov 20 '18 at 12:18
|
show 1 more comment
3
Are you doing this as an exercise? If not, you should just usesort()
– Karsten Koop
Nov 20 '18 at 11:03
I'm trying to translate a sortingmethod from Javascript to php... Why?
– B001ᛦ
Nov 20 '18 at 11:19
JavaScript allows accessing of non-existent array elements or string positions, and will just returnundefinedwithout issuing any warning or error; PHP however does not, and gives you an “undefined index/offset” in such a case. So you need to test whether what you want to access exists first.
– misorude
Nov 20 '18 at 11:41
@KarstenKoop: No but it is a part of a larger library that i am translating so i want it to be the same method.
– Pei-turn
Nov 20 '18 at 12:13
@B001ᛦ: because i need the code to run serverside and i dont have node.js
– Pei-turn
Nov 20 '18 at 12:18
3
3
Are you doing this as an exercise? If not, you should just use
sort()– Karsten Koop
Nov 20 '18 at 11:03
Are you doing this as an exercise? If not, you should just use
sort()– Karsten Koop
Nov 20 '18 at 11:03
I'm trying to translate a sortingmethod from Javascript to php... Why?
– B001ᛦ
Nov 20 '18 at 11:19
I'm trying to translate a sortingmethod from Javascript to php... Why?
– B001ᛦ
Nov 20 '18 at 11:19
JavaScript allows accessing of non-existent array elements or string positions, and will just return
undefined without issuing any warning or error; PHP however does not, and gives you an “undefined index/offset” in such a case. So you need to test whether what you want to access exists first.– misorude
Nov 20 '18 at 11:41
JavaScript allows accessing of non-existent array elements or string positions, and will just return
undefined without issuing any warning or error; PHP however does not, and gives you an “undefined index/offset” in such a case. So you need to test whether what you want to access exists first.– misorude
Nov 20 '18 at 11:41
@KarstenKoop: No but it is a part of a larger library that i am translating so i want it to be the same method.
– Pei-turn
Nov 20 '18 at 12:13
@KarstenKoop: No but it is a part of a larger library that i am translating so i want it to be the same method.
– Pei-turn
Nov 20 '18 at 12:13
@B001ᛦ: because i need the code to run serverside and i dont have node.js
– Pei-turn
Nov 20 '18 at 12:18
@B001ᛦ: because i need the code to run serverside and i dont have node.js
– Pei-turn
Nov 20 '18 at 12:18
|
show 1 more comment
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3
Are you doing this as an exercise? If not, you should just use
sort()– Karsten Koop
Nov 20 '18 at 11:03
I'm trying to translate a sortingmethod from Javascript to php... Why?
– B001ᛦ
Nov 20 '18 at 11:19
JavaScript allows accessing of non-existent array elements or string positions, and will just return
undefinedwithout issuing any warning or error; PHP however does not, and gives you an “undefined index/offset” in such a case. So you need to test whether what you want to access exists first.– misorude
Nov 20 '18 at 11:41
@KarstenKoop: No but it is a part of a larger library that i am translating so i want it to be the same method.
– Pei-turn
Nov 20 '18 at 12:13
@B001ᛦ: because i need the code to run serverside and i dont have node.js
– Pei-turn
Nov 20 '18 at 12:18