i want to create a mathematical formula in the context variable and use that formula in the job can anyone help please

[Anonymous]

talend for data integration, i want to create a mathematical formula in the context variable and use that formula in the job can anyone help please?

say formula is a+b and I want to store it in the context variable (context.c=a+b)

and then I want to use it in tjavaRow  int c= context.c(it should do the addition of a and b)

[Anonymous]

I'm afraid context variables are just variables. You cannot get them to act in this way. What is your use case? Maybe there is another way of achieving your requirement.

[Anonymous]

I need to take formula in context and I have to load formula from file to context since formula may change according to the requirement. In short I need to take formula from file to talend job(tMap or tJavaRow).

[Anonymous]

Can you give an example of the type of formula? Also, which product are you using? The Open Source Edition or the Enterprise Edition?

[Anonymous]

Hello,

Please use a tJava in Pre Job and write your formula.

context.c = a+b;

Then use context.c in the job and all child jobs.

Thanks,

Subhadip

[Anonymous]

I'm using talend open studio and formula some times (a*b*c)/d and some times (a*b*c*e)/d depends on the requirement. Can I get any solution to read the formula from file and execute the formula in talend job. Its going to be a great help...

[Anonymous]

OK, I have found a solution for you. It requires writing a Talend routine and using a third party library. There is a Java library found here (http://mathparser.org/) which allows you to what you want. Download the appropriate Jar and add a Talend routine like below....

package routines;

import org.mariuszgromada.math.mxparser.*;

public class Equations {

	public static Double runExpression(String expression, double a, double b, double c, double d, double f){
		
		Argument aVal = new Argument("a");
		Argument bVal = new Argument("b");
		Argument cVal = new Argument("c");
		Argument dVal = new Argument("d");
		Argument fVal = new Argument("f");
		
		aVal.setArgumentValue(a);
		bVal.setArgumentValue(b);
		cVal.setArgumentValue(c);
		dVal.setArgumentValue(d);
		fVal.setArgumentValue(f);
		
		//System.out.println(aVal.getArgumentName()+aVal.getArgumentValue());
		Expression ex = new Expression(expression, aVal, bVal, cVal, dVal, fVal);
		//System.out.println(ex.getExpressionString());
		//System.out.println(ex.getHelp());
		return ex.calculate();
		 
	}
}

You will need to set up the routine Jar dependencies by right-clicking and select "Edit Routine Libraries".

Once the above is done, you can supply your equations to a Context Variable and use that Context Variable at runtime with code similar to below...

	double a = 5.0;
	double b = 2.0;
	double c = 3.0;
	double d = 4.0;
	double f = 2.0;
	
        context.myEquation = "(a*b*c)/d"; 
        System.out.println(routines.Equations.runExpression(context.myEquation",a,b,c,d,f));
        context.myEquation = "(a*b*c*f)/d";
	System.out.println(routines.Equations.runExpression(context.myEquation,a,b,c,d,f));

Note that I didn't use "e" in the equations above since "e" is a reserved value for the mXParser tool. You will have to bare that in mind when using this method.