différence de deux valeurs consécutives dans une ArrayList: Android

Question

J'ai un ArrayList() qui stocke certaines données générées en temps réel. Je veux obtenir la différence de l'élément consécutif de la ArrayList

1. J'ai essayé

   ArrayList<Long> difference = new ArrayList<>(); 
   difference.add(durationInMs); 
   //tried to store 
   for (int d = 0; d < difference.size()-1; d++){ 
        time1 = difference.get(d); 
        time2 = difference.get(d + 1); 
        timeDifference = time2 - time1; 
   } 
   

2. Ce:

   ----------------

   ArrayList<Long> difference = new ArrayList<>(); 
   difference.add(durationInMs); 
   
   ArrayList<Long> tempArray = new ArrayList<>(); 
   tempArray.add(0, difference.get(0)); 
   
   for (int d = 0; d < difference.size()-1; d++){ 
        timeDifference = tempArray.get(d+1) - difference.get(d); 
   } 
   Log.d("time", String.valueOf(timeDifference)); 
   

3. De plus, cette enter link description here

Mais aucun d'entre eux ne semble m'obtenir la valeur soustraite entre 2 éléments consécutifs. Probablement le problème est que les valeurs sont générées en temps réel et que lors de la soustraction, la valeur suivante n'est pas encore générée. Comment est-ce que je fais?

UPDATE: la méthode (si elle contribue)

@Override 
public void onPreviewFrame(long startTime, int ySum, int uSum, int vSum, long endTime) { 
    begin = startTime; 
    img_Y_Avg = ySum; 
    img_U_Avg = uSum; 
    img_V_Avg = vSum; 
    end = endTime; 


    //set value of Y on the text view 
    TextView valueOfY = (TextView)findViewById(R.id.valueY); 
    //valueY = img_Y_Avg; 
    valueOfY.setText(Double.toString(img_Y_Avg)); 

    //set value of U on the text view 
    TextView valueOfU = (TextView)findViewById(R.id.valueU); 
    // valueU = img_U_Avg; 
    valueOfU.setText(Double.toString(img_U_Avg)); 

    //set value of V on the text view 
    TextView valueOfV = (TextView)findViewById(R.id.valueV); 
    //valueV = img_V_Avg; 
    valueOfV.setText(Double.toString(img_V_Avg)); 

    //start time in milliseconds 
    long StartDurationInMs = TimeUnit.MILLISECONDS.convert(begin, TimeUnit.MILLISECONDS); 
    ArrayList<Long> startOfTime = new ArrayList<>(); 
    startOfTime.add(StartDurationInMs); 
    Log.d("time", "start: "+String.valueOf(startOfTime)); 

    //store value to array list 
    ArrayList<Integer> yAverage = new ArrayList<>(); 
    yAverage.add(img_Y_Avg); 
    //Log.d("MyEntryData", String.valueOf(yAverage)); 

    //store u values to array 
    ArrayList<Integer> uAverage = new ArrayList<>(); 
    uAverage.add(img_U_Avg); 
    //Log.d("MyEntryData", String.valueOf(uAverage)); 

    //store u values to array 
    ArrayList<Integer> vAverage = new ArrayList<>(); 
    vAverage.add(img_V_Avg); 
    //Log.d("MyEntryData", String.valueOf(vAverage)); 
    //time between frames 

    //end time in milliseconds 
    long EndDurationInMs = TimeUnit.MILLISECONDS.convert(end, TimeUnit.MILLISECONDS); 
    ArrayList<Long> endOfTime = new ArrayList<>(); 
    endOfTime.add(EndDurationInMs); 


    Log.d("time", "end: "+String.valueOf(endOfTime)); 


    ArrayList<Long> getValues = new ArrayList<>(); 
    for(int i = 0; i < yAverage.size(); i++) { 
     getValues.add(startOfTime.get(i)); 
     getValues.add((long)(yAverage.get(i))); 
     getValues.add((long)(uAverage.get(i))); 
     getValues.add((long)(vAverage.get(i))); 
    } 


    String filename = new SimpleDateFormat("yyyyMMddHHmm'.csv'").format(new Date()); 

    File directoryDownload = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DOWNLOADS); 
    File logDir = new File (directoryDownload, "bpReader"); //Creates a new folder in DOWNLOAD directory 
    logDir.mkdirs(); 
    File file = new File(logDir, filename); 

    FileOutputStream outputStream = null; 
    try { 
      outputStream = new FileOutputStream(file, true); 
      //outputStream = openFileOutput(filename, Context.MODE_PRIVATE); 
      for (int i = 0; i < yAverage.size(); i += 4) { 
       outputStream.write((getValues.get(i) + ",").getBytes()); 
       outputStream.write((getValues.get(i + 1) + ",").getBytes()); 
       outputStream.write((getValues.get(i + 2) + ",").getBytes()); 
       outputStream.write((getValues.get(i + 3) + "\n").getBytes()); 

      } 
      outputStream.close(); 
     } catch (Exception e) { 
      e.printStackTrace(); 
     } 

    Log.d("MyEntryData", String.valueOf(getValues)); 


    handler = new Handler(); 
    final Runnable runnable = new Runnable() { 
     @Override 
     public void run() { 
      readingRemaining = readingRemaining -1; 

      if (readingRemaining > 0){ 
       plotGraph(img_Y_Avg); 
      } 
     } 
    }; 

    handler.postDelayed(runnable, 100); 

    //Log.d("MyEntryData", String.valueOf(img_Y_Avg +" "+ img_U_Avg+" "+img_V_Avg)); 

} 

Answer 1

Essayer de temps delta = difference.get (d + 1) - difference.get (d);

ArrayList<Long> difference = new ArrayList<>(); 
    for (int i = 0; i<10; i++) 
     difference.add((long)(Math.random() * 1000)); 
    for (int d = 0; d < difference.size()-1; d++){ 
     Log.i("diff", String.format(
       "element %d,%d:%d - %d = %d", 
       d+1, d, difference.get(d+1), difference.get(d), 
       difference.get(d+1) - difference.get(d))); 
    } 
    Log.i(TAG, "hello"); 

Sortie:

... I/diff: element 1,0:197 - 425 = -228 
... I/diff: element 2,1:389 - 197 = 192 
... I/diff: element 3,2:947 - 389 = 558 
... I/diff: element 4,3:510 - 947 = -437 
... I/diff: element 5,4:399 - 510 = -111 
... I/diff: element 6,5:971 - 399 = 572 
... I/diff: element 7,6:537 - 971 = -434 
... I/diff: element 8,7:326 - 537 = -211 
... I/diff: element 9,8:897 - 326 = 571 

Answer 2

Si vous craignez que le tableau est en cours de modification en temps réel que vous êtes en train de traiter, puis

Suggestion 1

Au Au moment où un nouveau point de données est généré, pourriez-vous regarder le point de données précédent et calculer delta à la volée, puis ajouter() le delta à un autre tableau?

long lastDatum = null; 
    ArrayList<long> diffArray = new ArrayList<>(); 

    void recordDataPoint(long datum) 
    { 
     if (lastDatum != null) { 
     diffArray.add(datum - lastDatum); 
     } 
     lastDatum = datum; 

     // ... do whatever else you need to do with datum.... 
    } 

Suggestion 2
Si le tableau est stable alors je pense que vous avez juste besoin de faire ceci:

// existing data is in durationInMs[] 

    ArrayList<Long> difference = new ArrayList<>(); 

    for (int d = 0; d < durationInMs.size()-1; d++){ 
     time1 = durationInMs.get(d); 
     time2 = durationInMs.get(d + 1); 
     timeDifference = time2 - time1; 

     difference.add(timeDifference); 
}