Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>This is an interesting algorithm for generating values. Here is an implementation that I have created based on the explanation give at <a href="http://www.gameprogrammer.com/fractal.html#diamond" rel="noreferrer">this page in the references from the wikipedia article</a>. It will create "spherical values" (wrapped at all the edges). There are notes in the comments for how to change it to generate new values on the edges instead of wrapping (though the meaning of average for the edges isn't really correct in these cases).</p> <pre><code>//size of grid to generate, note this must be a //value 2^n+1 final int DATA_SIZE = 9; //an initial seed value for the corners of the data final double SEED = 1000.0; double[][] data = new double[DATA_SIZE][DATA_SIZE]; //seed the data data[0][0] = data[0][DATA_SIZE-1] = data[DATA_SIZE-1][0] = data[DATA_SIZE-1][DATA_SIZE-1] = SEED; double h = 500.0;//the range (-h -&gt; +h) for the average offset Random r = new Random();//for the new value in range of h //side length is distance of a single square side //or distance of diagonal in diamond for(int sideLength = DATA_SIZE-1; //side length must be &gt;= 2 so we always have //a new value (if its 1 we overwrite existing values //on the last iteration) sideLength &gt;= 2; //each iteration we are looking at smaller squares //diamonds, and we decrease the variation of the offset sideLength /=2, h/= 2.0){ //half the length of the side of a square //or distance from diamond center to one corner //(just to make calcs below a little clearer) int halfSide = sideLength/2; //generate the new square values for(int x=0;x&lt;DATA_SIZE-1;x+=sideLength){ for(int y=0;y&lt;DATA_SIZE-1;y+=sideLength){ //x, y is upper left corner of square //calculate average of existing corners double avg = data[x][y] + //top left data[x+sideLength][y] +//top right data[x][y+sideLength] + //lower left data[x+sideLength][y+sideLength];//lower right avg /= 4.0; //center is average plus random offset data[x+halfSide][y+halfSide] = //We calculate random value in range of 2h //and then subtract h so the end value is //in the range (-h, +h) avg + (r.nextDouble()*2*h) - h; } } //generate the diamond values //since the diamonds are staggered we only move x //by half side //NOTE: if the data shouldn't wrap then x &lt; DATA_SIZE //to generate the far edge values for(int x=0;x&lt;DATA_SIZE-1;x+=halfSide){ //and y is x offset by half a side, but moved by //the full side length //NOTE: if the data shouldn't wrap then y &lt; DATA_SIZE //to generate the far edge values for(int y=(x+halfSide)%sideLength;y&lt;DATA_SIZE-1;y+=sideLength){ //x, y is center of diamond //note we must use mod and add DATA_SIZE for subtraction //so that we can wrap around the array to find the corners double avg = data[(x-halfSide+DATA_SIZE)%DATA_SIZE][y] + //left of center data[(x+halfSide)%DATA_SIZE][y] + //right of center data[x][(y+halfSide)%DATA_SIZE] + //below center data[x][(y-halfSide+DATA_SIZE)%DATA_SIZE]; //above center avg /= 4.0; //new value = average plus random offset //We calculate random value in range of 2h //and then subtract h so the end value is //in the range (-h, +h) avg = avg + (r.nextDouble()*2*h) - h; //update value for center of diamond data[x][y] = avg; //wrap values on the edges, remove //this and adjust loop condition above //for non-wrapping values. if(x == 0) data[DATA_SIZE-1][y] = avg; if(y == 0) data[x][DATA_SIZE-1] = avg; } } } //print out the data for(double[] row : data){ for(double d : row){ System.out.printf("%8.3f ", d); } System.out.println(); } </code></pre>
    singulars
    1. This table or related slice is empty.
    1. PODiamond square algorithm
      singulars
      1. PTQuestion
    1. PTAnswer
    1. This table or related slice is empty.
    1. USM. Jessup
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. PODiamond square algorithm
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    1. COI'll have to study it a little more for customization purposes and general knowledge, but it works! BTW, thanks for your time.
      singulars
      1. PO
      1. USGabriel A. Zorrilla
    2. CODo you get pinching of peaks and troughs when you use a high number of iterations?
      singulars
      1. PO
      1. USArcane Engineer
    3. CO"wrapped at all edges" is not a sphere. It's a toroid. You've made a dough-nut, not a globe. A globe has less of a circumference the further north you go. A doughnut does not. -- Not dissing the geometry, it's *WAY* easier, but it's not a sphere by any metric.
      singulars
      1. PO
      1. USTatarize
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload