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MQL4 - Preloading bars for a given timeframe

  • #1
  • First Post: Sep 2, 2012 2:00pm Sep 2, 2012 2:00pm
Hello,
In an expert adviser I would like to use iHigh and iLow functions for a timeframe which is different than the current timeframe. How can I be sure that a reasonable amount of bars are loaded for this timeframe? Can I call some function which will preload the bars on the chart?

Thanks
  • #2
  • Sep 2, 2012 3:51pm Sep 2, 2012 3:51pm
I don't think anybody has ever had that concern before. There have been some who were concerned about lack of bars for back testing, but I don't remember any who needed a lot of bars for live trading.

You didn't define reasonable and to most people, reasonable is the last few hundred bars which will no doubt be present on your chart, unless you have a peculiar broker. The way I would do it is use the Bars value and compare it to whatever number you want and issue an alert if it is less. Then you could manually load up the chart with the number of bars necessary. Otherwise you would have to review every chart on a regular basis to determine if there are sufficient bars.
  • #3
  • Sep 2, 2012 4:14pm Sep 2, 2012 4:14pm
Quoting jaxx80
Hello,
In an expert adviser I would like to use iHigh and iLow functions for a timeframe which is different than the current timeframe. How can I be sure that a reasonable amount of bars are loaded for this timeframe? Can I call some function which will preload the bars on the chart?

Thanks
There is a script on codebase for loading history data for all symbols on your Mt4.
http://codebase.mql4.com/6693

If you really need to integrate this into your EA,
it should be possible by modifying the code accordingly.

I just tested the script and yes, after attaching it to a random chart, it starts opening M1 of the first symbol it finds in symbol-list, loads data, then switches timeframe to M5 .... etc. until it has finished loading all history data for that symbol, then starts with M1 of the next symbol.

In your EA, you just "tell" the new function ( loading history data) the name of the symbol and maybe the period and let it do its work
on that symbol and you are done.
  • #4
  • Sep 2, 2012 4:35pm Sep 2, 2012 4:35pm
Quoting jaxx80
How can I be sure that a reasonable amount of bars are loaded for this timeframe?
You can check the nr of bars like this:
Inserted Code
nr_of_bars_on_Chart=iBars(cur_symbol, PERIOD_M15);
  • #5
  • Sep 3, 2012 2:29am Sep 3, 2012 2:29am
Quoting CodeMeister
I don't think anybody has ever had that concern before. There have been some who were concerned about lack of bars for back testing, but I don't remember any who needed a lot of bars for live trading.

You didn't define reasonable and to most people, reasonable is the last few hundred bars which will no doubt be present on your chart, unless you have a peculiar broker. The way I would do it is use the Bars value and compare it to whatever number you want and issue an alert if it is less. Then you could manually load up the chart with the number...
yes, but only if you use the EA yourself. If you send it to someone else, you will have to ask him to preload bars manually, which is not convinient.
  • #6
  • Sep 3, 2012 2:31am Sep 3, 2012 2:31am
Quoting fxtr51
There is a script on codebase for loading history data for all symbols on your Mt4.
http://codebase.mql4.com/6693

If you really need to integrate this into your EA,
it should be possible by modifying the code accordingly.

I just tested the script and yes, after attaching it to a random chart, it starts opening M1 of the first symbol it finds in symbol-list, loads data, then switches timeframe to M5 .... etc. until it has finished loading all history data for that symbol, then starts with M1 of the next symbol.

In your EA, you just...
Thanks.
I'll try it.

Do you know what will happen if my expert is attached on H1, and I try to get the iMA from D1, but there are not enough bars on D1? will MT4 load the bars automatically or it will return error?
  • #7
  • Sep 3, 2012 3:33am Sep 3, 2012 3:33am
Quoting jaxx80
Do you know what will happen if my expert is attached on H1, and I try to get the iMA from D1, but there are not enough bars on D1? will MT4 load the bars automatically or it will return error?
I donīt know.
You can test it.
  • #8
  • Last Post: Sep 3, 2012 4:52am Sep 3, 2012 4:52am
Quoting jaxx80
Thanks.
I'll try it.

Do you know what will happen if my expert is attached on H1, and I try to get the iMA from D1, but there are not enough bars on D1? will MT4 load the bars automatically or it will return error?
pretty sure it works exactly the same as if you ask for the high low open close of the current bar in any timeframe... the close is ever-changing until it finally reaches the end of that bars slice of time. the ma will just keep changing until it stops changing...
Congratulations ScalaFX for coming out of the closet!
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