How to sort an array?

Quoting hanover

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Lucklogic,

Good question. Assuming that I've understood you correctly.........

If I have to sort multiple items, I build a string that consists of: sort key, item1, item2, item3, etc.

However, you can't use MQL4's ArraySort() to sort string arrays. I've added more than 70 new functions to the MQL4 language, which I've shared freely here. Among these are array sort functions, and number-to-string and string-to-number formatting functions.

RSI is always a positive...

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Quoting futurespec

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Think that is what I was trying to suggest in post #10

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Quoting lucklogic

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Wow thank you for that, I'll certainly have a good look at the additional functions

One additional hint request from you - if I where to use an indicator that produced -ve and +ve values, what addition preprocessing would be required so that the string sorting could occur

Thanks again

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Quoting hanover

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To sort negative numbers, I would add a suitably large number (e.g. 999999) to convert all numbers to positive values, in the sort key, and use NumberToStr() to format them. Then I would include the number itself as an item at the rightmost end of the string. In the example below, I've allowed numbers up to 2 decimal places to be sorted:

array_to_sort[i] = NumberToStr(999999+RSI_value[i],"Z8.2") + pair_symbol[i] + NumberToStr(RSI_value[i],"Z-3.2");

Hence a value of -17.83 for AUDUSD...

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Quoting futurespec

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Don't want to step on any toes here (especially hanover as he has more brain cells than my 1 and does great work for all here) but what is wrong with the original idea ... surely that will sort -ve numbers equally well?

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Quoting lucklogic

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Once you get the idea of where the characters are and then the required formatting code, its quite easy !

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Quoting lucklogic

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string Current = Pairs[aa];
......
array_for_sorting[aa] = NumberToStr(999999+Tally_value[aa],"Z8.2") + Current[aa] + NumberToStr(Tally_value[aa],"Z-3.2");
.......
Now what could that be ?

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Quoting futurespec

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If my post in any way sounded like I was upset/ expecting an apology then I myself apologize to you.

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Quoting hanover

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Anyway, one error that I see is that you've defined Current as a string, and then you're attempting to reference it later as an array (see text in red typeface). All of the items being constructed/sorted/deconstructed need to be arrays.

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Quoting lucklogic

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Hi, well all that I have tried to do is copy your instruction - you provided the following example where pair_symbol is created as a string and is then apparently used as an array - Post 20.

string pair_symbol[10] = {"EURUSD","USDCAD","NZDJPY","GBPJPY","GBPCHF","AUDUSD","USDJPY","USDCHF","EURAUD","AUDCAD"};
double RSI_value[10] = {46,10,55,79,28,93,12,66,51,8};



// build sort array: first 3 characters are the RSI, then the corresponding pair symbol.........

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Quoting hanover

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Is this all of your code? If not, please post all of it as an attachment (because the FF forum engine inserts unwanted spaces, deletes backslash characters, etc). It's impossible to perform any kind of troubleshooting unless I can compile and run the whole script/indicator/EA myself. You'll need to attach the "10.2 TMA slope" .mq4 also, otherwise I won't be able to compile your .mq4

Also, is your code part of a script, EA or indicator?

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//+------------------------------------------------------------------+
//|                                                            x.mq4 |
//+------------------------------------------------------------------+

#include <hanover --- function header.mqh>

//+------------------------------------------------------------------+
int start()   {
//+------------------------------------------------------------------+

string array_for_sorting[]; 
for(int aa = 0; aa < ArraySize(Pairs); aa++)   {
  string Current = Pairs[aa];

  double valsort = MathAbs( iCustom(Current,PERIOD_H1,"10.2 TMAslope",eintPeriod,6,0)); // need the absolute values for sorting 
  double val1sort = MathAbs( iCustom(Current,PERIOD_H4,"10.2 TMAslope",eintPeriod,6,0)); // 
  double val2sort = MathAbs( iCustom(Current,PERIOD_D1,"10.2 TMAslope",eintPeriod,6,0)); // 


  // need to load up the tally_value array so we can sort by maximum value both +ve and -ve
  Tally_value[aa]= (valsort + val1sort + val2sort);

  array_for_sorting[aa] = NumberToStr(999999+Tally_value[aa],"Z8.2") + Current[aa] + NumberToStr(Tally_value[aa],"Z-3.2");
  // perform the sort....... 
  ShellsortStringArray(array_for_sorting,true); // true sorts in descending order

  } //MAIN LOOP for(int a = 0; a < ArraySize(Pairs); a++)

  // now deconstruct the sorted values back to the original arrays...... 
  for (int i=0; i<ArraySize(Pairs); i++) {
    Pairs[i]; = StringSubstr(array_for_sorting[i],11); // pair is stored in position 11 onward
    Tally_value[i] = StrToDouble(StringSubstr(array_for_sorting[i],17,21)); // RSI is stored in character positions 17 thru 21
  }

  return(0);
}
//+------------------------------------------------------------------+

#include <hanover --- extensible functions.mqh>

Quoting hanover

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pair_symbol is defined as a (10 element) array in the above code.

I am sorry, but unless you post the code as I asked, I can not help you further. I need to be able to compile and run the whole procedure, because I suspect that the compile error you described is being caused by something that you haven't posted here.

Otherwise this will likely end up being a slow and painful exchange of posts, and I'd like to clear this up for you, and then move on, as quickly as possible. I need to resume my own backlog of work on Monday.

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