Re: [amibroker] How to increment dates in a for loop?

[Steve Dugas]

I would think you could associate your dates to BarIndex() and increment that 
by 100, something like...

BegISbar = Valuewhen(  DateNum() == BegISdate, BarIndex() );
EndISbar = Valuewhen(  DateNum() == EndISdate, BarIndex() );
...
for (FromISbarNum = BegISbar; FromISbarNum <= EndISbar; FromISbarNum = 
FromISbarNum + StepIS)

  ----- Original Message ----- 
  From: ozzyapeman 
  To: amibroker@yahoogroups.com 
  Sent: Tuesday, May 12, 2009 8:18 PM
  Subject: [amibroker] How to increment dates in a for loop?




  Hello, hoping someone can point out a good method for incrementing dates. I 
am currently trying to build a basic Walk-Forward engine that does an 
Optimization on In-Sample (IS) data using one formula, followed by an 
Optimization on Out-Of-Sample (OOS) data using a second formula.  

  This is different than AB's built-in WF engine, which performs an 
Optimization, followed by a Backtest using only one formula.

  Anyway, I am currently stuck right at the beginning, trying to figure out a 
sensible way to increment dates. This is what I have so far:

  // datenum format:   10000 * (year - 1900) + 100 * month + day, 
  // so 2001-12-31 becomes 1011231 and 1995-12-31 becomes 951231

  BegISdate  = 1031201;
  EndISdate  = 1090201;
  StepIS     =     100;

  BegOOSdate = 1050101;
  EndOOSdate = 1090301;
  StepOOS    =     100;

  Formula1   = "F:\\formula1.afl";    
  Formula2   = "F:\\formula2.afl";
  Database   = "F:\\AB Databases\\MyDB";
  Settings   = "F:\\My Settings.ABS";


  for (FromISdateNum = BegISDate; FromISdateNum <= EndISdate; FromISdateNum = 
FromISdateNum + StepIS)
    {

        AB = CreateObject("Broker.Application"); 

                // Etc. .........

  Now the above won't exactly work because simply adding 100 to a datenum will 
not allow the datenum to correctly roll over from December to January. For 
example, incrementing 1031201 by 100 yields 1031301 instead of 1040101.

  I know I can first convert the datenum to a string, then build a parser that 
splits the datenum apart and analyzes the last four digits, converting 1301 to 
0101, then reconstitute the string and reconvert to a datenum again. But that 
all feels rather convoluted.

  Is there an easier way to increment dates in AFL? I've searched the help 
manual and can't seem to find anything. What if I first converted to DateTime 
format? Is there an easy way to step through that format month by month?

  Any pointers much appreciated.

  And when I complete the WF Opt-Opt engine, I will be happy to post it here, 
in case anyone else has a need for it.

  Thanks!