Sort 2 arrays by the same way

Question

I have two arrays that are not sorted: a float array (float[]), and a String array (String[]) for the descriptions.

I need to sort the float array from the highest value to the lowest, but the descriptions are in the String array and if I sort them, the String array won't be sorted accordingly.

In Processing, there is a sort(Array) function, but it only sorts one array.

How can I sort the float array and have the descriptions match?

float totalCount = 0;
float maxValue = 0;
String[] statusDescriptions = new String[finishStatusesJSON.size()];
float[] countData = new float[finishStatusesJSON.size()]; 
for (int i = 0; i < finishStatusesJSON.size(); i++) {
  JSONObject finishStatusJSON = (JSONObject) finishStatusesJSON.get(i);
  float count = finishStatusJSON.getFloat("count"); 
  String status = finishStatusJSON.getString("status");
  totalCount += count;
  statusDescriptions[i] = status;
  countData[i] = count;

  // Max value of the table
  if(maxValue < count) maxValue = count;

}

Create a simple class that holds both values and use that in your array — Joakim Danielson, Jan 30 '19 at 18:56
I wanted to avoid create a lot more code. Is this that hard to achive? — user10992206, Jan 30 '19 at 18:57
Possible duplicate of [Java - Sort one array based on values of another array?](https://stackoverflow.com/questions/28556129/java-sort-one-array-based-on-values-of-another-array) — Lev Leontev, Jan 30 '19 at 18:57
@LeoLeontev this is basic java, I can't use that 8 stuff here — user10992206, Jan 30 '19 at 18:59
you can use a `dictionary` to find the values of `String` array using float values as __key__. The you only need to order float array and get the String values from dictionary (HasMap). — elbraulio, Jan 30 '19 at 19:02

score 1 · Answer 1 · answered Jan 30 '19 at 18:59

1

One solution would be to create a class that contains your entries, i.e. that combines a float with its description. For example, if you store movies as strings and their scores as floats, you could create a class MovieScore that contains the movie description (the string) and its score (the float). You could make this class Comparable and then sort an array of MovieScores to achieve your goal.

answered Jan 30 '19 at 18:59

Yannick Buehler

84
9

this is not java 8 – user10992206 Jan 30 '19 at 18:59
2

@user10992206 This answer works in all versions of Java – 4castle Jan 30 '19 at 19:00

Joakim Danielson · Accepted Answer · 2019-01-30T19:23:57.660

How to use a simple class to hold both pieces of data and keep it in one array for easier sorting. Sorting is supported by implementing the Comparable protocol.

class Status implements Comparable<Status> {
    String  status;
    float count;

    public Status(String status, float count) {
        this.status = status;
        this.count = count;
    }

    @Override
    public int compareTo(Status s) {        
        if (this.count < s.count) {
            return 1;
        } else if (this.count > s.count) {
            return -1;
        }

        return 0;
    }
}

Status[] statusArray = new Status[finishStatusesJSON.size()];

for (int i = 0; i < finishStatusesJSON.size(); i++) {
    JSONObject finishStatusJSON = (JSONObject) finishStatusesJSON.get(i);
    Status status = new Status(finishStatusJSON.getString("status"), finishStatusJSON.getFloat("count")); 

    statusArray[i] = status;
}

Arrays.sort(statusArray);

@user10992206, hold on a second I am getting there. I forgot to include it. — Joakim Danielson, Jan 30 '19 at 19:07

Prometheos II · Answer 3 · 2019-01-30T19:57:12.903

1

Maybe you could use a Map<K,V> type of array, where the K would be the Float class, while the V would be the String class.

Thus, you could use the put(K,V) method, like below, and then, sort properly.

float count = finishStatusJSON.getFloat("count");
totalCount += count;

map.put( count, finishStatusJSON.getString("status") );

Although, it seems like you're talking about Processing, not Java.

Erratum: It might be better to use a SortedMap implementing class; since you would be able to put a Comparator directly into the constructor, or use the natural ordering, and the Map will sort itself.

If you still want to use a Map implementing class, then I suggest that you use Map's keySet() method, then follow the same algorithm as suggested in this answer.

However, I'm skeptical of using those classes in Processing, since it might be in fact invalid for its framework; but if it compiles and there is no execution error/exception, then it may be worth a try.

edited Jan 30 '19 at 19:57

answered Jan 30 '19 at 19:03

Prometheos II

334
3
14

but this is not sorted – user10992206 Jan 30 '19 at 19:05
Processing is inspired by Java, but it's still far from Java. You can't use class (static) methods, for example. – Prometheos II Jan 30 '19 at 19:35
I have edited my message. If the classes seem to work, then you should try with a [Comparator](https://docs.oracle.com/javase/8/docs/api/java/util/Comparator.html) class which will sort the keys in a decreasing order. – Prometheos II Jan 30 '19 at 19:59

Sort 2 arrays by the same way

3 Answers3