question about Previous()

[#1]

Hi,

please, look at my script:

-------------------------------------

load

  id,

  text,

  balance,

  Previous(debt)-balance as debt

;

load * inline [

id, text, balance, debt

0,      ,       , 400

1, aaa, 250, 0

2, bbb, 200, 0

3, ccc, 100, 0

];

-------------------------------------------

I expected this:

0,      ,       ,  -

1, aaa, 250, 150

2, bbb, 200, -50

3, ccc, 100, -150

but, the result is

0,      ,       ,  -

1, aaa, 250, 150

2, bbb, 200, -200

3, ccc, 100, -100

what's wrong?

thanks in advance!

[kaushiknsolanki · Accepted solution]

Try this,

Data:

LOAD *,If(Rowno()=1, debt,Peek(Bal)-balance) as Bal;

load * inline [

id, text, balance, debt

0,,, 400

1, aaa, 250, 0

2, bbb, 200, 0

3, ccc, 100, 0

];

Final:

NoConcatenate

Load id,text,balance,debt,if(debt=Bal,0,Bal) as Value Resident Data;

drop Table Data;

Regards,

Kaushik Solanki

[#3]

Many thanks, Kaushik!

Works good!

[aveeeeeee7en]

Hi Oleg

Do you know why this has happened???

That Previous() function gives you a different Result from Peek() function.

This has happened because of the below Reson:

Previous() operates on the Input to the Load statement,

whereas Peek() operates on the Output of the Load statement.

So, when is it best to use each function?

• The previous() and peek() functions could be used when a user needs to show the current value versus the previous value of a field that was loaded from the original file.

• The peek() function would be better suited when the user is targeting either a field that has not been previously loaded into the table or if the user needs to target a specific row.

See the detailed description here:

Peek() vs Previous() – When to Use Each

Hope that has given you some conceptual Clarity.

Regards

Av7eN