org.numenta.nupic.encoders.ScalarEncoder Maven / Gradle / Ivy
/* ---------------------------------------------------------------------
* Numenta Platform for Intelligent Computing (NuPIC)
* Copyright (C) 2014, Numenta, In Unless you have an agreement
* with Numenta, In, for a separate license for this software code, the
* following terms and conditions apply:
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 3 as
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
* See the GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
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package org.numenta.nupic.encoders;
import gnu.trove.list.TDoubleList;
import gnu.trove.list.array.TDoubleArrayList;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.LinkedHashSet;
import java.util.List;
import java.util.Map;
import java.util.Set;
import org.numenta.nupic.Connections;
import org.numenta.nupic.FieldMetaType;
import org.numenta.nupic.util.ArrayUtils;
import org.numenta.nupic.util.Condition;
import org.numenta.nupic.util.MinMax;
import org.numenta.nupic.util.SparseObjectMatrix;
import org.numenta.nupic.util.Tuple;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* DOCUMENTATION TAKEN DIRECTLY FROM THE PYTHON VERSION:
*
* A scalar encoder encodes a numeric (floating point) value into an array
* of bits. The output is 0's except for a contiguous block of 1's. The
* location of this contiguous block varies continuously with the input value.
*
* The encoding is linear. If you want a nonlinear encoding, just transform
* the scalar (e.g. by applying a logarithm function) before encoding.
* It is not recommended to bin the data as a pre-processing step, e.g.
* "1" = $0 - $.20, "2" = $.21-$0.80, "3" = $.81-$1.20, etc as this
* removes a lot of information and prevents nearby values from overlapping
* in the output. Instead, use a continuous transformation that scales
* the data (a piecewise transformation is fine).
*
*
* Parameters:
* -----------------------------------------------------------------------------
* w -- The number of bits that are set to encode a single value - the
* "width" of the output signal
* restriction: w must be odd to avoid centering problems.
*
* minval -- The minimum value of the input signal.
*
* maxval -- The upper bound of the input signal
*
* periodic -- If true, then the input value "wraps around" such that minval = maxval
* For a periodic value, the input must be strictly less than maxval,
* otherwise maxval is a true upper bound.
*
* There are three mutually exclusive parameters that determine the overall size of
* of the output. Only one of these should be specified to the constructor:
*
* n -- The number of bits in the output. Must be greater than or equal to w
* radius -- Two inputs separated by more than the radius have non-overlapping
* representations. Two inputs separated by less than the radius will
* in general overlap in at least some of their bits. You can think
* of this as the radius of the input.
* resolution -- Two inputs separated by greater than, or equal to the resolution are guaranteed
* to have different representations.
*
* Note: radius and resolution are specified w.r.t the input, not output. w is
* specified w.r.t. the output.
*
* Example:
* day of week.
* w = 3
* Minval = 1 (Monday)
* Maxval = 8 (Monday)
* periodic = true
* n = 14
* [equivalently: radius = 1.5 or resolution = 0.5]
*
* The following values would encode midnight -- the start of the day
* monday (1) -> 11000000000001
* tuesday(2) -> 01110000000000
* wednesday(3) -> 00011100000000
* ...
* sunday (7) -> 10000000000011
*
* Since the resolution is 12 hours, we can also encode noon, as
* monday noon -> 11100000000000
* monday midnight-> 01110000000000
* tuesday noon -> 00111000000000
* etc
*
*
* It may not be natural to specify "n", especially with non-periodic
* data. For example, consider encoding an input with a range of 1-10
* (inclusive) using an output width of 5. If you specify resolution =
* 1, this means that inputs of 1 and 2 have different outputs, though
* they overlap, but 1 and 1.5 might not have different outputs.
* This leads to a 14-bit representation like this:
*
* 1 -> 11111000000000 (14 bits total)
* 2 -> 01111100000000
* ...
* 10-> 00000000011111
* [resolution = 1; n=14; radius = 5]
*
* You could specify resolution = 0.5, which gives
* 1 -> 11111000... (22 bits total)
* 1.5 -> 011111.....
* 2.0 -> 0011111....
* [resolution = 0.5; n=22; radius=2.5]
*
* You could specify radius = 1, which gives
* 1 -> 111110000000.... (50 bits total)
* 2 -> 000001111100....
* 3 -> 000000000011111...
* ...
* 10 -> .....000011111
* [radius = 1; resolution = 0.2; n=50]
*
*
* An N/M encoding can also be used to encode a binary value,
* where we want more than one bit to represent each state.
* For example, we could have: w = 5, minval = 0, maxval = 1,
* radius = 1 (which is equivalent to n=10)
* 0 -> 1111100000
* 1 -> 0000011111
*
*
* Implementation details:
* --------------------------------------------------------------------------
* range = maxval - minval
* h = (w-1)/2 (half-width)
* resolution = radius / w
* n = w * range/radius (periodic)
* n = w * range/radius + 2 * h (non-periodic)
*
* @author metaware
*/
public class ScalarEncoder extends Encoder {
private static final Logger LOGGER = LoggerFactory.getLogger(ScalarEncoder.class);
/**
* Constructs a new {@code ScalarEncoder}
*/
ScalarEncoder() {}
/**
* Returns a builder for building ScalarEncoders.
* This builder may be reused to produce multiple builders
*
* @return a {@code ScalarEncoder.Builder}
*/
public static Encoder.Builder builder() {
return new ScalarEncoder.Builder();
}
/**
* Returns true if the underlying encoder works on deltas
*/
@Override
public boolean isDelta() {
return false;
}
/**
* w -- number of bits to set in output
* minval -- minimum input value
* maxval -- maximum input value (input is strictly less if periodic == True)
*
* Exactly one of n, radius, resolution must be set. "0" is a special
* value that means "not set".
*
* n -- number of bits in the representation (must be > w)
* radius -- inputs separated by more than, or equal to this distance will have non-overlapping
* representations
* resolution -- inputs separated by more than, or equal to this distance will have different
* representations
*
* name -- an optional string which will become part of the description
*
* clipInput -- if true, non-periodic inputs smaller than minval or greater
* than maxval will be clipped to minval/maxval
*
* forced -- if true, skip some safety checks (for compatibility reasons), default false
*/
public void init() {
if(getW() % 2 == 0) {
throw new IllegalStateException(
"W must be an odd number (to eliminate centering difficulty)");
}
setHalfWidth((getW() - 1) / 2);
// For non-periodic inputs, padding is the number of bits "outside" the range,
// on each side. I.e. the representation of minval is centered on some bit, and
// there are "padding" bits to the left of that centered bit; similarly with
// bits to the right of the center bit of maxval
setPadding(isPeriodic() ? 0 : getHalfWidth());
if(!Double.isNaN(getMinVal()) && !Double.isNaN(getMaxVal())) {
if(getMinVal() >= getMaxVal()) {
throw new IllegalStateException("maxVal must be > minVal");
}
setRangeInternal(getMaxVal() - getMinVal());
}
// There are three different ways of thinking about the representation. Handle
// each case here.
initEncoder(getW(), getMinVal(), getMaxVal(), getN(), getRadius(), getResolution());
//nInternal represents the output area excluding the possible padding on each side
setNInternal(getN() - 2 * getPadding());
if(getName() == null) {
if((getMinVal() % ((int)getMinVal())) > 0 ||
(getMaxVal() % ((int)getMaxVal())) > 0) {
setName("[" + getMinVal() + ":" + getMaxVal() + "]");
}else{
setName("[" + (int)getMinVal() + ":" + (int)getMaxVal() + "]");
}
}
//Checks for likely mistakes in encoder settings
if(!isForced()) {
checkReasonableSettings();
}
description.add(new Tuple((name = getName()).equals("None") ? "[" + (int)getMinVal() + ":" + (int)getMaxVal() + "]" : name, 0));
}
/**
* There are three different ways of thinking about the representation.
* Handle each case here.
*
* @param c
* @param minVal
* @param maxVal
* @param n
* @param radius
* @param resolution
*/
public void initEncoder(int w, double minVal, double maxVal, int n, double radius, double resolution) {
if(n != 0) {
if(!Double.isNaN(minVal) && !Double.isNaN(maxVal)) {
if(!isPeriodic()) {
setResolution(getRangeInternal() / (getN() - getW()));
}else{
setResolution(getRangeInternal() / getN());
}
setRadius(getW() * getResolution());
if(isPeriodic()) {
setRange(getRangeInternal());
}else{
setRange(getRangeInternal() + getResolution());
}
}
}else{
if(radius != 0) {
setResolution(getRadius() / w);
}else if(resolution != 0) {
setRadius(getResolution() * w);
}else{
throw new IllegalStateException(
"One of n, radius, resolution must be specified for a ScalarEncoder");
}
if(isPeriodic()) {
setRange(getRangeInternal());
}else{
setRange(getRangeInternal() + getResolution());
}
double nFloat = w * (getRange() / getRadius()) + 2 * getPadding();
setN((int)Math.ceil(nFloat));
}
}
/**
* Return the bit offset of the first bit to be set in the encoder output.
* For periodic encoders, this can be a negative number when the encoded output
* wraps around.
*
* @param c the memory
* @param input the input data
* @return an encoded array
*/
public Integer getFirstOnBit(double input) {
if(input == SENTINEL_VALUE_FOR_MISSING_DATA) {
return null;
}else{
if(input < getMinVal()) {
if(clipInput() && !isPeriodic()) {
LOGGER.info("Clipped input " + getName() + "=" + input + " to minval " + getMinVal());
input = getMinVal();
}else{
throw new IllegalStateException("input (" + input +") less than range (" +
getMinVal() + " - " + getMaxVal());
}
}
}
if(isPeriodic()) {
if(input >= getMaxVal()) {
throw new IllegalStateException("input (" + input +") greater than periodic range (" +
getMinVal() + " - " + getMaxVal());
}
}else{
if(input > getMaxVal()) {
if(clipInput()) {
LOGGER.info("Clipped input " + getName() + "=" + input + " to maxval " + getMaxVal());
input = getMaxVal();
}else{
throw new IllegalStateException("input (" + input +") greater than periodic range (" +
getMinVal() + " - " + getMaxVal());
}
}
}
int centerbin;
if(isPeriodic()) {
centerbin = ((int)((input - getMinVal()) * getNInternal() / getRange())) + getPadding();
}else{
centerbin = ((int)(((input - getMinVal()) + getResolution()/2) / getResolution())) + getPadding();
}
return centerbin - getHalfWidth();
}
/**
* Check if the settings are reasonable for the SpatialPooler to work
* @param c
*/
public void checkReasonableSettings() {
if(getW() < 21) {
throw new IllegalStateException(
"Number of bits in the SDR (%d) must be greater than 2, and recommended >= 21 (use forced=True to override)");
}
}
/**
* {@inheritDoc}
*/
@Override
public Set getDecoderOutputFieldTypes() {
return new LinkedHashSet<>(Arrays.asList(FieldMetaType.FLOAT, FieldMetaType.INTEGER));
}
/**
* Should return the output width, in bits.
*/
@Override
public int getWidth() {
return getN();
}
/**
* {@inheritDoc}
* NO-OP
*/
@Override
public int[] getBucketIndices(String input) { return null; }
/**
* Returns the bucket indices.
*
* @param input
*/
@Override
public int[] getBucketIndices(double input) {
int minbin = getFirstOnBit(input);
//For periodic encoders, the bucket index is the index of the center bit
int bucketIdx;
if(isPeriodic()) {
bucketIdx = minbin + getHalfWidth();
if(bucketIdx < 0) {
bucketIdx += getN();
}
}else{//for non-periodic encoders, the bucket index is the index of the left bit
bucketIdx = minbin;
}
return new int[] { bucketIdx };
}
/**
* Encodes inputData and puts the encoded value into the output array,
* which is a 1-D array of length returned by {@link Connections#getW()}.
*
* Note: The output array is reused, so clear it before updating it.
* @param inputData Data to encode. This should be validated by the encoder.
* @param output 1-D array of same length returned by {@link Connections#getW()}
*/
@Override
public void encodeIntoArray(Double input, int[] output) {
if(Double.isNaN(input)) {
Arrays.fill(output, 0);
return;
}
Integer bucketVal = getFirstOnBit(input);
if(bucketVal != null) {
int bucketIdx = bucketVal;
Arrays.fill(output, 0);
int minbin = bucketIdx;
int maxbin = minbin + 2*getHalfWidth();
if(isPeriodic()) {
if(maxbin >= getN()) {
int bottombins = maxbin - getN() + 1;
int[] range = ArrayUtils.range(0, bottombins);
ArrayUtils.setIndexesTo(output, range, 1);
maxbin = getN() - 1;
}
if(minbin < 0) {
int topbins = -minbin;
ArrayUtils.setIndexesTo(
output, ArrayUtils.range(getN() - topbins, getN()), 1);
minbin = 0;
}
}
ArrayUtils.setIndexesTo(output, ArrayUtils.range(minbin, maxbin + 1), 1);
}
// Added guard against immense string concatenation
if(LOGGER.isTraceEnabled()) {
LOGGER.trace("");
LOGGER.trace("input: " + input);
LOGGER.trace("range: " + getMinVal() + " - " + getMaxVal());
LOGGER.trace("n:" + getN() + "w:" + getW() + "resolution:" + getResolution() +
"radius:" + getRadius() + "periodic:" + isPeriodic());
LOGGER.trace("output: " + Arrays.toString(output));
LOGGER.trace("input desc: " + decode(output, ""));
}
}
/**
* Returns a {@link DecodeResult} which is a tuple of range names
* and lists of {@link RangeLists} in the first entry, and a list
* of descriptions for each range in the second entry.
*
* @param encoded the encoded bit vector
* @param parentFieldName the field the vector corresponds with
* @return
*/
@Override
public DecodeResult decode(int[] encoded, String parentFieldName) {
// For now, we simply assume any top-down output greater than 0
// is ON. Eventually, we will probably want to incorporate the strength
// of each top-down output.
if(encoded == null || encoded.length < 1) {
return null;
}
int[] tmpOutput = Arrays.copyOf(encoded, encoded.length);
// ------------------------------------------------------------------------
// First, assume the input pool is not sampled 100%, and fill in the
// "holes" in the encoded representation (which are likely to be present
// if this is a coincidence that was learned by the SP).
// Search for portions of the output that have "holes"
int maxZerosInARow = getHalfWidth();
for(int i = 0;i < maxZerosInARow;i++) {
int[] searchStr = new int[i + 3];
Arrays.fill(searchStr, 1);
ArrayUtils.setRangeTo(searchStr, 1, -1, 0);
int subLen = searchStr.length;
// Does this search string appear in the output?
if(isPeriodic()) {
for(int j = 0;j < getN();j++) {
int[] outputIndices = ArrayUtils.range(j, j + subLen);
outputIndices = ArrayUtils.modulo(outputIndices, getN());
if(Arrays.equals(searchStr, ArrayUtils.sub(tmpOutput, outputIndices))) {
ArrayUtils.setIndexesTo(tmpOutput, outputIndices, 1);
}
}
}else{
for(int j = 0;j < getN() - subLen + 1;j++) {
if(Arrays.equals(searchStr, ArrayUtils.sub(tmpOutput, ArrayUtils.range(j, j + subLen)))) {
ArrayUtils.setRangeTo(tmpOutput, j, j + subLen, 1);
}
}
}
}
LOGGER.trace("raw output:" + Arrays.toString(
ArrayUtils.sub(encoded, ArrayUtils.range(0, getN()))));
LOGGER.trace("filtered output:" + Arrays.toString(tmpOutput));
// ------------------------------------------------------------------------
// Find each run of 1's.
int[] nz = ArrayUtils.where(tmpOutput, new Condition.Adapter() {
@Override
public boolean eval(int n) {
return n > 0;
}
});
List runs = new ArrayList(); //will be tuples of (startIdx, runLength)
Arrays.sort(nz);
int[] run = new int[] { nz[0], 1 };
int i = 1;
while(i < nz.length) {
if(nz[i] == run[0] + run[1]) {
run[1] += 1;
}else{
runs.add(new Tuple(run[0], run[1]));
run = new int[] { nz[i], 1 };
}
i += 1;
}
runs.add(new Tuple(run[0], run[1]));
// If we have a periodic encoder, merge the first and last run if they
// both go all the way to the edges
if(isPeriodic() && runs.size() > 1) {
int l = runs.size() - 1;
if(((Integer)runs.get(0).get(0)) == 0 && ((Integer)runs.get(l).get(0)) + ((Integer)runs.get(l).get(1)) == getN()) {
runs.set(l, new Tuple((Integer)runs.get(l).get(0),
((Integer)runs.get(l).get(1)) + ((Integer)runs.get(0).get(1)) ));
runs = runs.subList(1, runs.size());
}
}
// ------------------------------------------------------------------------
// Now, for each group of 1's, determine the "left" and "right" edges, where
// the "left" edge is inset by halfwidth and the "right" edge is inset by
// halfwidth.
// For a group of width w or less, the "left" and "right" edge are both at
// the center position of the group.
int left = 0;
int right = 0;
List ranges = new ArrayList();
for(Tuple tupleRun : runs) {
int start = (Integer)tupleRun.get(0);
int runLen = (Integer)tupleRun.get(1);
if(runLen <= getW()) {
left = right = start + runLen / 2;
}else{
left = start + getHalfWidth();
right = start + runLen - 1 - getHalfWidth();
}
double inMin, inMax;
// Convert to input space.
if(!isPeriodic()) {
inMin = (left - getPadding()) * getResolution() + getMinVal();
inMax = (right - getPadding()) * getResolution() + getMinVal();
}else{
inMin = (left - getPadding()) * getRange() / getNInternal() + getMinVal();
inMax = (right - getPadding()) * getRange() / getNInternal() + getMinVal();
}
// Handle wrap-around if periodic
if(isPeriodic()) {
if(inMin >= getMaxVal()) {
inMin -= getRange();
inMax -= getRange();
}
}
// Clip low end
if(inMin < getMinVal()) {
inMin = getMinVal();
}
if(inMax < getMinVal()) {
inMax = getMinVal();
}
// If we have a periodic encoder, and the max is past the edge, break into
// 2 separate ranges
if(isPeriodic() && inMax >= getMaxVal()) {
ranges.add(new MinMax(inMin, getMaxVal()));
ranges.add(new MinMax(getMinVal(), inMax - getRange()));
}else{
if(inMax > getMaxVal()) {
inMax = getMaxVal();
}
if(inMin > getMaxVal()) {
inMin = getMaxVal();
}
ranges.add(new MinMax(inMin, inMax));
}
}
String desc = generateRangeDescription(ranges);
String fieldName;
// Return result
if(parentFieldName != null && !parentFieldName.isEmpty()) {
fieldName = String.format("%s.%s", parentFieldName, getName());
}else{
fieldName = getName();
}
RangeList inner = new RangeList(ranges, desc);
Map fieldsDict = new HashMap();
fieldsDict.put(fieldName, inner);
return new DecodeResult(fieldsDict, Arrays.asList(fieldName));
}
/**
* Generate description from a text description of the ranges
*
* @param ranges A list of {@link MinMax}es.
*/
public String generateRangeDescription(List ranges) {
StringBuilder desc = new StringBuilder();
int numRanges = ranges.size();
for(int i = 0;i < numRanges;i++) {
if(ranges.get(i).min() != ranges.get(i).max()) {
desc.append(String.format("%.2f-%.2f", ranges.get(i).min(), ranges.get(i).max()));
}else{
desc.append(String.format("%.2f", ranges.get(i).min()));
}
if(i < numRanges - 1) {
desc.append(", ");
}
}
return desc.toString();
}
/**
* Return the internal topDownMapping matrix used for handling the
* bucketInfo() and topDownCompute() methods. This is a matrix, one row per
* category (bucket) where each row contains the encoded output for that
* category.
*
* @param c the connections memory
* @return the internal topDownMapping
*/
public SparseObjectMatrix getTopDownMapping() {
if(topDownMapping == null) {
//The input scalar value corresponding to each possible output encoding
if(isPeriodic()) {
setTopDownValues(
ArrayUtils.arange(getMinVal() + getResolution() / 2.0,
getMaxVal(), getResolution()));
}else{
//Number of values is (max-min)/resolutions
setTopDownValues(
ArrayUtils.arange(getMinVal(), getMaxVal() + getResolution() / 2.0,
getResolution()));
}
}
//Each row represents an encoded output pattern
int numCategories = getTopDownValues().length;
SparseObjectMatrix topDownMapping;
setTopDownMapping(
topDownMapping = new SparseObjectMatrix(
new int[] { numCategories }));
double[] topDownValues = getTopDownValues();
int[] outputSpace = new int[getN()];
double minVal = getMinVal();
double maxVal = getMaxVal();
for(int i = 0;i < numCategories;i++) {
double value = topDownValues[i];
value = Math.max(value, minVal);
value = Math.min(value, maxVal);
encodeIntoArray(value, outputSpace);
topDownMapping.set(i, Arrays.copyOf(outputSpace, outputSpace.length));
}
return topDownMapping;
}
/**
* {@inheritDoc}
*
* @param the input value, in this case a double
* @return a list of one input double
*/
@Override
public TDoubleList getScalars(S d) {
TDoubleList retVal = new TDoubleArrayList();
retVal.add((Double)d);
return retVal;
}
/**
* Returns a list of items, one for each bucket defined by this encoder.
* Each item is the value assigned to that bucket, this is the same as the
* EncoderResult.value that would be returned by getBucketInfo() for that
* bucket and is in the same format as the input that would be passed to
* encode().
*
* This call is faster than calling getBucketInfo() on each bucket individually
* if all you need are the bucket values.
*
* @param returnType class type parameter so that this method can return encoder
* specific value types
*
* @return list of items, each item representing the bucket value for that
* bucket.
*/
@SuppressWarnings("unchecked")
@Override
public List getBucketValues(Class t) {
if(bucketValues == null) {
SparseObjectMatrix topDownMapping = getTopDownMapping();
int numBuckets = topDownMapping.getMaxIndex() + 1;
bucketValues = new ArrayList();
for(int i = 0;i < numBuckets;i++) {
((List)bucketValues).add((Double)getBucketInfo(new int[] { i }).get(0).get(1));
}
}
return (List)bucketValues;
}
/**
* {@inheritDoc}
*/
@Override
public List getBucketInfo(int[] buckets) {
SparseObjectMatrix topDownMapping = getTopDownMapping();
//The "category" is simply the bucket index
int category = buckets[0];
int[] encoding = topDownMapping.getObject(category);
//Which input value does this correspond to?
double inputVal;
if(isPeriodic()) {
inputVal = getMinVal() + getResolution() / 2 + category * getResolution();
}else{
inputVal = getMinVal() + category * getResolution();
}
return Arrays.asList(new EncoderResult(inputVal, inputVal, encoding));
}
/**
* {@inheritDoc}
*/
@Override
public List topDownCompute(int[] encoded) {
//Get/generate the topDown mapping table
SparseObjectMatrix topDownMapping = getTopDownMapping();
// See which "category" we match the closest.
int category = ArrayUtils.argmax(rightVecProd(topDownMapping, encoded));
return getBucketInfo(new int[]{category});
}
/**
* Returns a list of {@link Tuple}s which in this case is a list of
* key value parameter values for this {@code ScalarEncoder}
*
* @return a list of {@link Tuple}s
*/
public List dict() {
List l = new ArrayList();
l.add(new Tuple("maxval", getMaxVal()));
l.add(new Tuple("bucketValues", getBucketValues(Double.class)));
l.add(new Tuple("nInternal", getNInternal()));
l.add(new Tuple("name", getName()));
l.add(new Tuple("minval", getMinVal()));
l.add(new Tuple("topDownValues", Arrays.toString(getTopDownValues())));
l.add(new Tuple("clipInput", clipInput()));
l.add(new Tuple("n", getN()));
l.add(new Tuple("padding", getPadding()));
l.add(new Tuple("range", getRange()));
l.add(new Tuple("periodic", isPeriodic()));
l.add(new Tuple("radius", getRadius()));
l.add(new Tuple("w", getW()));
l.add(new Tuple("topDownMappingM", getTopDownMapping()));
l.add(new Tuple("halfwidth", getHalfWidth()));
l.add(new Tuple("resolution", getResolution()));
l.add(new Tuple("rangeInternal", getRangeInternal()));
return l;
}
/**
* Returns a {@link EncoderBuilder} for constructing {@link ScalarEncoder}s
*
* The base class architecture is put together in such a way where boilerplate
* initialization can be kept to a minimum for implementing subclasses, while avoiding
* the mistake-proneness of extremely long argument lists.
*
* @see ScalarEncoder.Builder#setStuff(int)
*/
public static class Builder extends Encoder.Builder {
private Builder() {}
@Override
public ScalarEncoder build() {
//Must be instantiated so that super class can initialize
//boilerplate variables.
encoder = new ScalarEncoder();
//Call super class here
super.build();
////////////////////////////////////////////////////////
// Implementing classes would do setting of specific //
// vars here together with any sanity checking //
////////////////////////////////////////////////////////
((ScalarEncoder)encoder).init();
return (ScalarEncoder)encoder;
}
}
}
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