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Shuffling a JSON array in Java
The 2019 Stack Overflow Developer Survey Results Are InSimplification of byte array comparison algorithmShuffling an array of cardsShuffling a deckShuffling array elements in CShuffling a list of track indicesLogic for shuffling sliding puzzleShuffling chunks of ints in an arrayBasic Pong GameJava Market Summary - JSONShuffling an array keeping some elements fixed
.everyoneloves__top-leaderboard:empty,.everyoneloves__mid-leaderboard:empty,.everyoneloves__bot-mid-leaderboard:empty{ margin-bottom:0;
}
$begingroup$
Since I did not get a satisfactory answer here (and I really needed to get it going on this weekend), I decided to implement my own Fisher–Yates shuffle, porting the code I found in other SO posts. I know my programming technique is far from optimal, so I decided to post this here.
What do you think? Can it be improved?
public static JSONArray shuffleJsonArray (JSONArray array) throws JSONException {
// Implementing Fisher–Yates shuffle
Random rnd = new Random();
for (int i = array.length() - 1; i >= 0; i--)
{
int j = rnd.nextInt(i + 1);
// Simple swap
Object object = array.get(j);
array.put(j, array.get(i));
array.put(i, object);
}
return array;
}
java array json shuffle
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
$endgroup$
add a comment |
$begingroup$
Since I did not get a satisfactory answer here (and I really needed to get it going on this weekend), I decided to implement my own Fisher–Yates shuffle, porting the code I found in other SO posts. I know my programming technique is far from optimal, so I decided to post this here.
What do you think? Can it be improved?
public static JSONArray shuffleJsonArray (JSONArray array) throws JSONException {
// Implementing Fisher–Yates shuffle
Random rnd = new Random();
for (int i = array.length() - 1; i >= 0; i--)
{
int j = rnd.nextInt(i + 1);
// Simple swap
Object object = array.get(j);
array.put(j, array.get(i));
array.put(i, object);
}
return array;
}
java array json shuffle
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
$endgroup$
add a comment |
$begingroup$
Since I did not get a satisfactory answer here (and I really needed to get it going on this weekend), I decided to implement my own Fisher–Yates shuffle, porting the code I found in other SO posts. I know my programming technique is far from optimal, so I decided to post this here.
What do you think? Can it be improved?
public static JSONArray shuffleJsonArray (JSONArray array) throws JSONException {
// Implementing Fisher–Yates shuffle
Random rnd = new Random();
for (int i = array.length() - 1; i >= 0; i--)
{
int j = rnd.nextInt(i + 1);
// Simple swap
Object object = array.get(j);
array.put(j, array.get(i));
array.put(i, object);
}
return array;
}
java array json shuffle
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
$endgroup$
Since I did not get a satisfactory answer here (and I really needed to get it going on this weekend), I decided to implement my own Fisher–Yates shuffle, porting the code I found in other SO posts. I know my programming technique is far from optimal, so I decided to post this here.
What do you think? Can it be improved?
public static JSONArray shuffleJsonArray (JSONArray array) throws JSONException {
// Implementing Fisher–Yates shuffle
Random rnd = new Random();
for (int i = array.length() - 1; i >= 0; i--)
{
int j = rnd.nextInt(i + 1);
// Simple swap
Object object = array.get(j);
array.put(j, array.get(i));
array.put(i, object);
}
return array;
}
java array json shuffle
java array json shuffle
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
edited Jul 4 '17 at 3:35
Jamal♦
30.6k11121227
30.6k11121227
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
asked Apr 4 '11 at 6:08
AleadamAleadam
11315
11315
add a comment |
add a comment |
1 Answer
1
active
oldest
votes
$begingroup$
It runs in $O(n)$ time so I'm not sure there's a way to improve this. It looks like you've implemented the algorithm pretty well, according the Fisher-Yates shuffle.
You might consider not using Object if you can use the type that's stored in the array instead.
I also thought I read somewhere that it should be safe to loop to $n/2$ instead of $n$ (because you're swapping with elements from $1 cdots n$ so in theory, you shouldn't need to swap every element), but I don't have hard proof of that, so you take your chances ;)
edited 5 hours ago
esote
3,02611241
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
$endgroup$
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it usingJSONObjectinstead ofObjectbut then I changed it to make it more reusable. What would be the advantage of usingJSONObjectinstead?
$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to useObject, but I don't know if you can do that with JSONArray.
$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
add a comment |
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1 Answer
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active
oldest
votes
1 Answer
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active
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votes
$begingroup$
It runs in $O(n)$ time so I'm not sure there's a way to improve this. It looks like you've implemented the algorithm pretty well, according the Fisher-Yates shuffle.
You might consider not using Object if you can use the type that's stored in the array instead.
I also thought I read somewhere that it should be safe to loop to $n/2$ instead of $n$ (because you're swapping with elements from $1 cdots n$ so in theory, you shouldn't need to swap every element), but I don't have hard proof of that, so you take your chances ;)
edited 5 hours ago
esote
3,02611241
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
$endgroup$
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it usingJSONObjectinstead ofObjectbut then I changed it to make it more reusable. What would be the advantage of usingJSONObjectinstead?
$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to useObject, but I don't know if you can do that with JSONArray.
$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
add a comment |
$begingroup$
It runs in $O(n)$ time so I'm not sure there's a way to improve this. It looks like you've implemented the algorithm pretty well, according the Fisher-Yates shuffle.
You might consider not using Object if you can use the type that's stored in the array instead.
I also thought I read somewhere that it should be safe to loop to $n/2$ instead of $n$ (because you're swapping with elements from $1 cdots n$ so in theory, you shouldn't need to swap every element), but I don't have hard proof of that, so you take your chances ;)
edited 5 hours ago
esote
3,02611241
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
$endgroup$
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it usingJSONObjectinstead ofObjectbut then I changed it to make it more reusable. What would be the advantage of usingJSONObjectinstead?
$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to useObject, but I don't know if you can do that with JSONArray.
$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
add a comment |
$begingroup$
It runs in $O(n)$ time so I'm not sure there's a way to improve this. It looks like you've implemented the algorithm pretty well, according the Fisher-Yates shuffle.
You might consider not using Object if you can use the type that's stored in the array instead.
I also thought I read somewhere that it should be safe to loop to $n/2$ instead of $n$ (because you're swapping with elements from $1 cdots n$ so in theory, you shouldn't need to swap every element), but I don't have hard proof of that, so you take your chances ;)
edited 5 hours ago
esote
3,02611241
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
$endgroup$
It runs in $O(n)$ time so I'm not sure there's a way to improve this. It looks like you've implemented the algorithm pretty well, according the Fisher-Yates shuffle.
You might consider not using Object if you can use the type that's stored in the array instead.
I also thought I read somewhere that it should be safe to loop to $n/2$ instead of $n$ (because you're swapping with elements from $1 cdots n$ so in theory, you shouldn't need to swap every element), but I don't have hard proof of that, so you take your chances ;)
edited 5 hours ago
esote
3,02611241
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
edited 5 hours ago
esote
3,02611241
edited 5 hours ago
esote
3,02611241
edited 5 hours ago
esote
3,02611241
3,02611241
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
answered Apr 4 '11 at 15:15
FrustratedWithFormsDesignerFrustratedWithFormsDesigner
484210
484210
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it usingJSONObjectinstead ofObjectbut then I changed it to make it more reusable. What would be the advantage of usingJSONObjectinstead?
$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to useObject, but I don't know if you can do that with JSONArray.
$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
add a comment |
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it usingJSONObjectinstead ofObjectbut then I changed it to make it more reusable. What would be the advantage of usingJSONObjectinstead?
$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to useObject, but I don't know if you can do that with JSONArray.
$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it using
JSONObject instead of Object but then I changed it to make it more reusable. What would be the advantage of using JSONObject instead?$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
Thanks for looking at it. I based it on that wikipedia page and a couple of posts in SO. I will keep in mind the n/2 loops to change it if needed. Lastly, I wrote it using
JSONObject instead of Object but then I changed it to make it more reusable. What would be the advantage of using JSONObject instead?$endgroup$
– Aleadam
Apr 4 '11 at 15:30
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to use
Object, but I don't know if you can do that with JSONArray.$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
@Aleadam: I don't know the JSONArray datatype well, I guess I was trying to suggest to use Java generics so you don't have to use
Object, but I don't know if you can do that with JSONArray.$endgroup$
– FrustratedWithFormsDesigner
Apr 4 '11 at 15:36
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
$begingroup$
I also think that there is no faster way for shuffling an array. Every try in doing it faster (O(log n) or O(sqrt n)) would result in a poorly shuffled array.
$endgroup$
– leemes
May 17 '12 at 20:58
add a comment |
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