/**
* Updates the minimum duty cycles defining normal activity for a column. A column with activity
* duty cycle below this minimum threshold is boosted.
*
* @param c
*/
public void updateMinDutyCycles(Connections c) {
if (c.getGlobalInhibition() || c.getInhibitionRadius() > c.getNumInputs()) {
updateMinDutyCyclesGlobal(c);
} else {
updateMinDutyCyclesLocal(c);
}
}
/**
* Update the inhibition radius. The inhibition radius is a measure of the square (or hypersquare)
* of columns that each a column is "connected to" on average. Since columns are are not connected
* to each other directly, we determine this quantity by first figuring out how many *inputs* a
* column is connected to, and then multiplying it by the total number of columns that exist for
* each input. For multiple dimension the aforementioned calculations are averaged over all
* dimensions of inputs and columns. This value is meaningless if global inhibition is enabled.
*
* @param c the {@link Connections} (spatial pooler memory)
*/
public void updateInhibitionRadius(Connections c) {
if (c.getGlobalInhibition()) {
c.setInhibitionRadius(ArrayUtils.max(c.getColumnDimensions()));
return;
}
TDoubleArrayList avgCollected = new TDoubleArrayList();
int len = c.getNumColumns();
for (int i = 0; i < len; i++) {
avgCollected.add(avgConnectedSpanForColumnND(c, i));
}
double avgConnectedSpan = ArrayUtils.average(avgCollected.toArray());
double diameter = avgConnectedSpan * avgColumnsPerInput(c);
double radius = (diameter - 1) / 2.0d;
radius = Math.max(1, radius);
c.setInhibitionRadius((int) Math.round(radius));
}
/**
* Performs inhibition. This method calculates the necessary values needed to actually perform
* inhibition and then delegates the task of picking the active columns to helper functions.
*
* @param c the {@link Connections} matrix
* @param overlaps an array containing the overlap score for each column. The overlap score for a
* column is defined as the number of synapses in a "connected state" (connected synapses)
* that are connected to input bits which are turned on.
* @return
*/
public int[] inhibitColumns(Connections c, double[] overlaps) {
overlaps = Arrays.copyOf(overlaps, overlaps.length);
double density;
double inhibitionArea;
if ((density = c.getLocalAreaDensity()) <= 0) {
inhibitionArea = Math.pow(2 * c.getInhibitionRadius() + 1, c.getColumnDimensions().length);
inhibitionArea = Math.min(c.getNumColumns(), inhibitionArea);
density = c.getNumActiveColumnsPerInhArea() / inhibitionArea;
density = Math.min(density, 0.5);
}
// Add our fixed little bit of random noise to the scores to help break ties.
// ArrayUtils.d_add(overlaps, c.getTieBreaker());
if (c.getGlobalInhibition()
|| c.getInhibitionRadius() > ArrayUtils.max(c.getColumnDimensions())) {
return inhibitColumnsGlobal(c, overlaps, density);
}
return inhibitColumnsLocal(c, overlaps, density);
}
