C2SChunk.java

package water.fvec;

import java.util.Arrays;
import water.*;

/**
 * The scale/bias function, where data is in SIGNED bytes before scaling.
 */
public class C2SChunk extends Chunk {
  static final int OFF=8+8;
  public double _scale;
  long _bias;
  C2SChunk( byte[] bs, long bias, double scale ) { _mem=bs; _start = -1; _len = (_mem.length-OFF)>>1;
    _bias = bias; _scale = scale;
    UDP.set8d(_mem,0,scale);
    UDP.set8 (_mem,8,bias );
  }
  @Override protected final long at8_impl( int i ) {
    long res = UDP.get2(_mem,(i<<1)+OFF);
    if( res == C2Chunk._NA ) throw new IllegalArgumentException("at8 but value is missing");
    return (long)((res + _bias)*_scale);
  }
  @Override protected final double atd_impl( int i ) {
    long res = UDP.get2(_mem,(i<<1)+OFF);
    return (res == C2Chunk._NA)?Double.NaN:(res + _bias)*_scale;
  }
  @Override protected final boolean isNA_impl( int i ) { return UDP.get2(_mem,(i<<1)+OFF) == C2Chunk._NA; }
  @Override boolean set_impl(int idx, long l) {
    long res = (long)(l/_scale)-_bias; // Compressed value
    double d = (res+_bias)*_scale;     // Reverse it
    if( (long)d != l ) return false;   // Does not reverse cleanly?
    if( !(Short.MIN_VALUE < res && res <= Short.MAX_VALUE) ) return false; // Out-o-range for a short array
    UDP.set2(_mem,(idx<<1)+OFF,(short)res);
    return true;
  }
  @Override boolean set_impl(int i, double d) {
    short s = (short)((d/_scale)-_bias);
    if( s == C2Chunk._NA ) return false;
    double d2 = (s+_bias)*_scale;
    if( d!=d2 ) return false;
    UDP.set2(_mem,(i<<1)+OFF,s);
    return true;
  }
  @Override boolean set_impl(int i, float f ) { return false; }
  @Override boolean setNA_impl(int idx) { UDP.set2(_mem,(idx<<1)+OFF,(short)C2Chunk._NA); return true; }
  @Override boolean hasFloat() { return _scale < 1.0; }
  @Override public AutoBuffer write(AutoBuffer bb) { return bb.putA1(_mem,_mem.length); }
  @Override public C2SChunk read(AutoBuffer bb) {
    _mem = bb.bufClose();
    _start = -1;
    _len = (_mem.length-OFF)>>1;
    _scale= UDP.get8d(_mem,0);
    _bias = UDP.get8 (_mem,8);
    return this;
  }
  @Override NewChunk inflate_impl(NewChunk nc) {
    double dx = Math.log10(_scale);
    assert PrettyPrint.fitsIntoInt(dx);
    nc.set_len(nc.set_sparseLen(0));
    final int len = len();
    for( int i=0; i<len; i++ ) {
      int res = UDP.get2(_mem,(i<<1)+OFF);
      if( res == C2Chunk._NA ) nc.addNA();
      else nc.addNum((res+_bias),(int)dx);
    }
    return nc;
  }
  public int pformat_len0() { 
    if( _scale==0.01 ) return 5;
    return hasFloat() ? pformat_len0(_scale,5) : super.pformat_len0(); 
  }
  public String  pformat0() { 
    if( _scale==0.01 ) return "%7.2f";
    return hasFloat() ? "% 10.4e" : super.pformat0(); 
  }
}