com.scudata.expression.fn.gather.Median Maven / Gradle / Ivy

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SPL(Structured Process Language) A programming language specially for structured data computing.
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package com.scudata.expression.fn.gather;

import com.scudata.common.MessageManager;
import com.scudata.common.RQException;
import com.scudata.dm.Context;
import com.scudata.dm.Sequence;
import com.scudata.expression.Expression;
import com.scudata.expression.Gather;
import com.scudata.expression.IParam;
import com.scudata.resources.EngineMessage;

/**
 * ?ۺϺ???Median??
 * 
 * @author ??־??
 *
 */
public class Median extends Gather  {
	int	parK = 0;	// ѡ???ĸ??ֶΡ???Ϊ0????ʽ??ֵΪ??
	int	parN = 0;	// ?ֶ??ٶΣ???Ϊ0??ʾ??ֵΪ?ա?
	private Expression exp;	// ???????ʽ
	
	/**
	 * ????median(k:n, exp)?ֱ????k??n??exp
	 */
	public void prepare(Context ctx) {
		if (param == null || param.getSubSize() != 2) {
			MessageManager mm = EngineMessage.get();
			throw new RQException("median" + mm.getMessage("function.invalidParam"));
		}
		
		IParam sub0 = param.getSub(0);
		IParam sub1 = param.getSub(1);
		exp = sub1.getLeafExpression();
		
		// median k??n??????????Ϊ?գ???ʱȡ??ֵ??
		if (null == sub0) {
			parK	= 1;
			parN	= 2;
			return;
		}
		
		sub1 = sub0.getSub(1);
		sub0 = sub0.getSub(0);
		
		try {
			Expression data;
			Object obj;
			if (null == sub0)
				parK = 0;
			else {
				data = sub0.getLeafExpression();
				obj = data.calculate(null);
				parK = (Integer)obj;
			}
			
			if (null == sub1)
				parN = 0;
			else {
				data = sub1.getLeafExpression();
				obj = data.calculate(null);
				parN = (Integer)obj;
			}
			
			if (parN < 2) {
				MessageManager mm = EngineMessage.get();
				throw new RQException("median" + mm.getMessage("function.invalidParam"));
			}
			
			if (parK > parN) {
				MessageManager mm = EngineMessage.get();
				throw new RQException("median" + mm.getMessage("function.invalidParam"));
			}
			
		} catch(Exception e) {
			MessageManager mm = EngineMessage.get();
			throw new RQException("median" + mm.getMessage("function.invalidParam"));
		}
	}

	/**
	 * ??һ????¼???ӵ?meidan?м????ݻ????????ʱ???????ϵ?median??
	 * 		?????????ݰ??????????ݺͷ????????ݡ?
	 * 		??????????Ҫ?????в?ֺ󣬺ϲ?????????ֺ?????ݻ????????У???????һ????֣?
	 * 		??????????ֱ?Ӻϲ???
	 * @param	oldValue	??ǰ???м?????
	 * @param	ctx	?????ı??????ṩ?????м????ݵ???????
	 */
	public Object gather(Object oldValue, Context ctx) {
		Object val = exp.calculate(ctx);
		if (val == null)
			return oldValue;
		
		if(oldValue == null) {
			if (val instanceof Sequence) {
				return val;
			} else {
				Sequence seq = new Sequence();
				seq.add(val);
				return seq;
			}
		} else {
			if (val instanceof Sequence) {
				((Sequence)oldValue).addAll((Sequence)val);
			} else {
				((Sequence)oldValue).add(val);
			}
			
			return oldValue;
		}

	}

	/**
	 * ?Ѽ????????ݺϲ?Ϊ?ڴ???м?????
	 * 		
	 */
	public Object gather(Context ctx) {
		Object val = exp.calculate(ctx);

		if (val instanceof Sequence) {
			return val;
		} else {
			Sequence seq = new Sequence();
			seq.add(val);
			return seq;
		}
	}

	/**
	 * ????median?ڵĲ???????ԭ????ʽ?ַ?????
	 * @param	q	??ԭʱ????Ӧ???????С?
	 */
	public Expression getRegatherExpression(int q) {
		String str = "median("+parK+":"+parN+",#"+ + q + ")";
		return new Expression(str);

	}

	public Object calculate(Context ctx) {
		MessageManager mm = EngineMessage.get();
		throw new RQException(mm.getMessage("Expression.unknownFunction") + "median");
	}

	/**
	 * ?Ƿ???Ҫ????ͳ?Ʋ???
	 */
	public boolean needFinish() {
		return true;
	}
	
	/**
	 * ͳ????ʱ?м????ݣ????????ս????
	 */
	public Object finish(Object val) {
		if (val == null || !(val instanceof Sequence)) {
			return val;
		}
	
		Sequence seq = ((Sequence)val).sort(null);
		return seq.median(1, seq.length(), parK, parN);	
	}
	
	public int getParK() {
		return parK;
	}

	public int getParN() {
		return parN;
	}

	public Expression getExp() {
		return exp;
	}
}