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> How could I use VarSet to create an array of arrays?
As I wrote before multi-dimensional array in linear computer memory is represented
in all languages as array (or set) of array(s). Having that in mind it is easy to implement
multi-dim via VarSet/VarGet
I explained it here
http://finance.groups.yahoo.com/group/amibroker/message/86446
Quote:
"Desired access to tablename[x][y] can be implemented as follows
using VarSet / VarGet (note that this is only ONE OF MANY possible ways)
function Set2DimTable( tablename, x, y, value )
{
VarSet( tablename + StrFormat("%05.0f%05.0f", x, y ), value );
}
function Get2DimTable( tablename, x, y )
{
return VarGet( tablename + StrFormat("%05.0f%05.0f", x, y ) );
}
Example use:
Set2DimTable( "blabla", 2, 3, High[ 0 ] );
"
You can of course instead of storing single values you can store entire arrays.
Like this:
function Set2DimTableRow( tablename, row, array )
{
VarSet( tablename + StrFormat("%05.0f", row), array );
}
function Get2DimTableRow( tablename, row)
{
return VarGet( tablename + StrFormat("%05.0f", column ) );
}
In this second example, single row represents "normal" AFL array,
but you can store a number of rows (arrays) in a set of rows making
it array of the array.
Multi-dimensional arrays by nature are always mapped in one way
or another into linear (single-dimension) computer memory. Whenever
this mapping is done by means of multiple dynamic variables explicitely
like in the example above, or by the pointer manipulation (as in C),
or by another subscript - is pretty cosmetic issue and does not really matter.
Dynamic variables (VarGet/VarSet) and arrays are basically orthogonal concepts,
with only one difference, while arrays allow only NUMERIC subscripts,
dynamic variables allow free text subscripts (it is form of map or hash table - and internally
implemented as hash table), which actually is more flexible, not less as some may think.
Best regards,
Tomasz Janeczko
amibroker.com
----- Original Message -----
From: "brian_z111" <brian_z111@xxxxxxxxx>
To: <amibroker@xxxxxxxxxxxxxxx>
Sent: Tuesday, March 24, 2009 4:38 PM
Subject: [amibroker] Re: AFL 101
> Yes, I understand the distinction between array and multi-dimensional arrays and I appreciate ABs' capabilities in the speed with
> which it handles arrays.
>
>> I can understand your difficulties but the fact that you don't >understand something
>> or don't know how to use some functionality, does not mean that it >does not exist nor that it is not useful.
>
> Yes, that is true (except for the difficulties part ... I am not having any difficulties .... happy to discuss the pros and cons
> of AB for the benefit of newcomers though).
>
>> I sincerely appreciate your willingness to teach me what array is, >and what can be considered array function and what not.
>
> I don't know about that.
>
> Really I think it us just an interesting and educational discussion and other 101'ers must have got something out of it (possibly
> they found the Wiki link relevant too).
>
> Once again I thank you for a very good educational post.
>
>
> Re VarSet/VarGet:
>
> You have mentioned using them to produce dynamic arrays before (in this forum I think) BUT the help manual doesn't say anything
> about the possibility in using them that way .... it indicates that the function only accepts a value (singular) for the argument
> and the example uses only a single value .... unless you changed something in the beta (I don't use beta releases ... I wait for
> the new version upgrade + manual).
>
> How could I use VarSet to create an array of arrays?
>
>
> VARSET
> - sets the value of dynamic variable Miscellaneous functions
> (AFL 2.60)
>
>
> SYNTAX VarSet( ''varname'', value )
> RETURNS NUMBER
> FUNCTION Sets the value of dynamic variable. Returns 1 on success, 0 on failure.
> Dynamic variables are variables that are named dynamically, typically by creating a variable name from a static part and a
> variable part. The following example dynamically constructs the variable name from a variable prefix and a static suffix.
>
> EXAMPLE for( i = 1; i < 10; i++ )
> {
> VarSet( "C"+i, Ref( C, -i ) );
> }
>
> // creates variables C1, C2, C3, C4, ...., C10 equal to Ref( C, -1 ), Ref( C, -2 ), ..., Ref( C, -10 )
> // respectively
>
>
>
>
>
>
>
> --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@xxx> wrote:
>>
>> Hello,
>>
>> Sorry, but it is complete waste of time to discuss basics and wikipedia refs.
>> You are mixing terms and you don't really understand what I am saying.
>>
>> FWIW: matrix is not the same array, at least not in the meaning I used in the post.
>> When I speak about array - I mean one dimensional array (vector) the only one that is
>> directly representable in computer (linear) memory.
>> And array are of course natively supported in AFL (unlike other languages that DO NOT feature
>> array operations (you can not use simply operator + to add arrays (element by element) in other general purpose languages).
>> Matrix is 2 and higher dimension - the "array of the array(s)"
>>
>> (FWIW: MATLAB, IDL, S-lang are NOT general purpose languages. General purpose languages
>> are those in which actual applications are written, i.e. C, C++, Java, Basic, Pascal, etc).
>>
>> Your response clearly shows that you don't even know what you want
>> (see "very good for developers/instutions and the handful of traders who want to write their own trading program [...]
>> hardly what the average trader wants to have to do before they can start trading" in the response
>> to me pointing out direct database read/write interface that you claimed does not exist ).
>>
>>
>> I can understand your difficulties but the fact that you don't understand something
>> or don't know how to use some functionality, does not mean that it does not exist nor that it is not useful.
>> Some things simply require learning and time to "sink in". Take your time and you will see enourmous
>> possibilities existing in AFL and will understand that the limit is only your imagination.
>>
>> I sincerely appreciate your willingness to teach me what array is, and what can be considered array function and what not,
>> what is native function or not, but as far as I remember I wrote AmiBroker myself so probably, I know a little about all that
>> already.
>>
>> Best regards,
>> Tomasz Janeczko
>> amibroker.com
>> ----- Original Message -----
>> From: "brian_z111" <brian_z111@xxx>
>> To: <amibroker@xxxxxxxxxxxxxxx>
>> Sent: Tuesday, March 24, 2009 2:27 PM
>> Subject: [amibroker] Re: AFL 101
>>
>>
>> > Hello Tomasz,
>> >
>> > Thanks for your educational post, I thoroughly enjoyed it.
>> >
>> > Quirky != bad;
>> >
>> > (some people like quirkiness ... like Bob Dylan in his song "Simple Twist of Fate")
>> >
>> > Of course I am just giving an opinion from my perspective (personal).
>> >
>> > Re your points:
>> >
>> > C language - I was just quoting from one of your posts .... I should have given the link because you did include some context
>> >
>> > http://finance.groups.yahoo.com/group/amibroker/message/135059
>> >
>> >> As for "matrix" operations - that this does not belong to the >definition of any general purpose language.
>> >
>> > I did a little bit of reading on 'languages that have array functions' when we had a short discussion on array programming
>> > before
>> > and found this link:
>> >
>> > http://en.wikipedia.org/wiki/Comparison_of_programming_languages_(array)
>> >
>> > (it comes from the Wikipedia array page)
>> >
>> > http://en.wikipedia.org/wiki/Array
>> >
>> > As I said, there is no point in comparing AFL to a GP language .... it is quirky to me that AFL is an array language and
>> > doesn't
>> > have a full suite of array functions .... perhaps other languages that are intended to handle price arrays etc would be a
>> > better
>> > comparison.
>> >
>> >> Having said that, for anyone needing multiple dimensional arrays in AFL there are several options:
>> >
>> >> a) use VarGet/VarSet (the 2-dim array is simply array of the array, so for N:M 2-dim array you need N AFL arrays)
>> >> b) using embedded JScript parts with AFL
>> >> c) using free open source Osaka plugin (you can extend it to your needs since all sources are available)
>> >> d) using any external COM object (written in VB for example if you need that)
>> >
>> > Except for a) none of these meet the criteria of "Native" to the language (AFL)
>> >
>> > VarGet/VarSet can hardly be described as a suite of array functions.
>> >
>> >
>> > Neither a, b, c or d achieve your own stated objective:
>> >
>> >> SIMPLICITY OF USE plus compactness of code is the paramount design >decision.
>> >
>> >> The database is exposed in two ways:
>> >> First (more general)
>> >> full OLE read/write direct access to the database - see Stocks/Stock/Quotations/Quotation objects:
>> >> http://www.amibroker.com/guide/objects.html
>> >> - and this OLE interface is DIRECTLY available from AFL level.
>> >
>> >
>> > That is very good for developers/instutions and the handful of traders who want to write their own trading program built around
>> > AB.
>> >
>> >
>> .
>> >
>> > Anyway, all of this could be done much easier from within AFL using AFL functions .... there is no need at all to use OLE for
>> > this
>> > type of thing .... it seems like overkill to me for a simple array processing language.
>> >
>> >
>> >
>> >> Second (easier)
>> >> AddToComposite/Foreign - gives you easy to use way to STORE and >READ from the AmiBroker database.
>> >
>> > ATC is time dependent ... when timeframe compression is used it starts to become quirky and that is just the beginning.
>> >
>> > Once again hardly a substitute for a full suite of native database functions.
>> >
>> >
>> > --- In amibroker@xxxxxxxxxxxxxxx, "Tomasz Janeczko" <groups@> wrote:
>> >>
>> >> Hello,
>> >>
>> >> There are several misconceptions in what was written here.
>> >> AFL is specifically designed to protect the newbie and people without coding experience
>> >> from programming stuff like memory allocation/deallocation, pointer manipulation,
>> >> declarations, type casting, etc.
>> >>
>> >> So although it looks like C it is way more easy than C.
>> >>
>> >> What is single operator in AFL (like array addition) involves many line of code in C
>> >> plus memory allocation/deallocation (and keeping track on all that).
>> >>
>> >> SIMPLICITY OF USE plus compactness of code is the paramount design decision.
>> >> That's why arrays in AFL are automatically managed, have size that automatically
>> >> refers to "visible" area, so you can simply add arrays with single + operator.
>> >>
>> >> With general purpose C language with "normal" arrays you would need to manage memory for arrays by yourself,
>> >> alignment (if size differs which elements to add), looping (you need to perform calculations
>> >> on individual elements of array).
>> >> (maybe you don't know but in C and there are no built-in dynamic arrays, only fixed compile-time size is supported,
>> >> and dynamic array is implemented via pointers and explicit memory allocation malloc/free)
>> >>
>> >> As for "matrix" operations - that this does not belong to the definition of any general purpose language.
>> >>
>> >> There are no "matrix" operations in any popular general purpose language C/C++/Java/JScript/Basic/Pascal.
>> >>
>> >> In C/C++ even scalar trigonometric operations like sin( x) or string concatenation are NOT part of the language.
>> >>
>> >> The language itself defines:
>> >> a) syntax
>> >> b) basic arithmetic operators + precedence working on primitive types only (scalar integer and/or float)
>> >> c) flow control (conditional execution, loops)
>> >> d) structural concepts (variables/functions/procedures/structures/objects)
>> >> e) some miscellaneous stuff like run-time type info, exception handling etc.
>> >>
>> >> And that's it.
>> >>
>> >> Anything more is supplied by LIBRARIES. In C there is a library for basic string manipulation (such as concatenation
>> >> - strcat) or floating point. The same with any high-level stuff like matrices - this is the area which
>> >> is implemented by EXTERNAL libraries (not part of the language).
>> >> Libraries in AFL can be provided by:
>> >> a) #include - the AFL code implementing features via functions
>> >> b) AmiBroker Development Kit - allowing to write extensions (functions) as a DLL in any compiled language.
>> >> c) JScript/VBScript
>> >> d) any external COM object http://www.amibroker.com/guide/a_aflcom.html
>> >>
>> >> This covers any imaginable application and any imaginable need you may have.
>> >>
>> >> Having said that, for anyone needing multiple dimensional arrays in AFL there are several options:
>> >> a) use VarGet/VarSet (the 2-dim array is simply array of the array, so for N:M 2-dim array you need N AFL arrays)
>> >> b) using embedded JScript parts with AFL
>> >> c) using free open source Osaka plugin (you can extend it to your needs since all sources are available)
>> >> d) using any external COM object (written in VB for example if you need that)
>> >>
>> >> If anyone is "advanced enough" to need multiple dimensional arrays, it is also "advanced enough" to use these options
>> >> without any trouble.
>> >>
>> >>
>> >> Also with regards to:
>> >> > - some of the architecture of AB is quirky also e.g. essentially it is a database, at the binary level, but you can't write
>> >> > directly to the native database
>> >> That is entirely not true.
>> >> The database is exposed in two ways:
>> >> First (more general)
>> >> full OLE read/write direct access to the database - see Stocks/Stock/Quotations/Quotation objects:
>> >> http://www.amibroker.com/guide/objects.html
>> >> - and this OLE interface is DIRECTLY available from AFL level.
>> >>
>> >> Second (easier)
>> >> AddToComposite/Foreign - gives you easy to use way to STORE and READ from the AmiBroker database.
>> >>
>> >> Best regards,
>> >> Tomasz Janeczko
>> >> amibroker.com
>> >> ----- Original Message -----
>> >> From: "brian_z111" <brian_z111@>
>> >> To: <amibroker@xxxxxxxxxxxxxxx>
>> >> Sent: Tuesday, March 24, 2009 1:46 AM
>> >> Subject: [amibroker] Re: AFL 101
>> >>
>> >>
>> >> > My perspective as a newcomer to programming when I started into AB/AFL around 2-3 years ago:
>> >> >
>> >> > - Tomasz says that AB is most like C
>> >> > - primarily one has to learn AFL fullstop
>> >> > - experienced programmers sometimes have to unlearn somethings and find this hard to do for a while
>> >> > - in some ways programming naivity paid off for me as I am at home with array programming
>> >> > - in other places I am lost because nothing can fill the missing link of not being familiar with syntax that is common to
>> >> > other
>> >> > languages (called experience)
>> >> > - AFL is quirky ..... some things that intuitively and logically seem needed are 'missing' and then you have to work around
>> >> > that
>> >> > e.g. IMO it is bizarre that AFL has been around for many years but doesn't have dynamic arrays or matrix functions ... the
>> >> > quirky
>> >> > aspects of AFL make it extremely difficult for lay people ... every time you get on a roll you find an exception
>> >> > - some of the architecture of AB is quirky also e.g. essentially it is a database, at the binary level, but you can't write
>> >> > directly to the native database
>> >> > - to save you future distress....many in the past have asked for an AFL book...the logic seems compelling to me
>> >> > - everyone starts from a different place so some need an 'Intro to AB', book
>> >> > - I like Howards contributions overall but IMO it is rather old world to publish in hard copy ... an ebook would be much
>> >> > better
>> >> > ... we have to consider that AB/AFL is way beyond the 500 pages allocated to it ib Howard's 2 books.
>> >> > - the AFL library is not the place to learn code ... good for sharing code between experienced AFL'ers
>> >> > - this forum is a book and contains at least 1000* the code, help, code and trading tips available anywhere else .....
>> >> > unfortunately it lacks sections, an index and topics etc .... once again the logic for a better forum (from an educational
>> >> > perspective) seems compelling.
>> >> >
>> >> > (Sorry Rik but Google searching Yahoo doesn't reference threads does it?)
>> >> >
>> >> > - AB/AFL is huge ... I don't think any layperson will ever cover it all without a big effort to become a programming expert,
>> >> > albeit one who specialises in AFL
>> >> >
>> >> > - AB is not a democracy or an open project
>> >> >
>> >> > BTW all of the advice given in this thread so far is spot on.
>> >> >
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > --- In amibroker@xxxxxxxxxxxxxxx, "louies88" <Louies88@> wrote:
>> >> >>
>> >> >> I think Amibroker is great, especially its AFL. Although I don't know enough about it to claim that it's superior than most
>> >> >> other
>> >> >> scripting languages out there, I know for a fact that this is one of the best. That also begs the question of how a person
>> >> >> w/
>> >> >> virtually no programming background can get started w/ AFL. I followed this forum long enough to note that some of you in
>> >> >> here
>> >> >> are excellent coders. The codes that I often see are flawless and eloquent, which then makes me think how long does it take
>> >> >> a
>> >> >> coding newbie such as myself to attain that coding level.
>> >> >>
>> >> >> I look at it this way. Coding a computer language is pretty similar to learning a foreign language. I remember how my first
>> >> >> English class went. I started out by learning a few basic vocabulary words, then use some of it in the form of a noun, then
>> >> >> a
>> >> >> verb, finally an object. Sentence structures, or in computer language better known as syntax, govern if a sentence is
>> >> >> grammatically correct or if it's not. With that in mind, I also started out by looking at the AFL Library in Amibroker. I
>> >> >> downloaded all of the functions in the hope of building myself an Amibroker vocabulary and started to put some of the basic
>> >> >> vocabulary words together to make a "sentence."
>> >> >>
>> >> >> However, since there isn't any kind of document FORMALLY teaching the ABC of coding in Amibroker, I'm left w/ a question
>> >> >> how
>> >> >> does
>> >> >> Amibroker syntax work? Some of the experienced coders here often compare AFL syntax to that of C++. But for a person w/
>> >> >> neither
>> >> >> background in AFL or C++ or any other computer langugae, the question remains: How do I get start? Where's the square one?
>> >> >>
>> >> >> Anybody w/ such experience is highly appreciated if he/she's willing to shed a light on this.
>> >> >>
>> >> >>
>> >> >> Thanks
>> >> >>
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > ------------------------------------
>> >> >
>> >> > **** IMPORTANT PLEASE READ ****
>> >> > This group is for the discussion between users only.
>> >> > This is *NOT* technical support channel.
>> >> >
>> >> > TO GET TECHNICAL SUPPORT send an e-mail directly to
>> >> > SUPPORT {at} amibroker.com
>> >> >
>> >> > TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
>> >> > http://www.amibroker.com/feedback/
>> >> > (submissions sent via other channels won't be considered)
>> >> >
>> >> > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
>> >> > http://www.amibroker.com/devlog/
>> >> >
>> >> > Yahoo! Groups Links
>> >> >
>> >> >
>> >> >
>> >>
>> >
>> >
>> >
>> >
>> > ------------------------------------
>> >
>> > **** IMPORTANT PLEASE READ ****
>> > This group is for the discussion between users only.
>> > This is *NOT* technical support channel.
>> >
>> > TO GET TECHNICAL SUPPORT send an e-mail directly to
>> > SUPPORT {at} amibroker.com
>> >
>> > TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
>> > http://www.amibroker.com/feedback/
>> > (submissions sent via other channels won't be considered)
>> >
>> > For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
>> > http://www.amibroker.com/devlog/
>> >
>> > Yahoo! Groups Links
>> >
>> >
>> >
>>
>
>
>
>
> ------------------------------------
>
> **** IMPORTANT PLEASE READ ****
> This group is for the discussion between users only.
> This is *NOT* technical support channel.
>
> TO GET TECHNICAL SUPPORT send an e-mail directly to
> SUPPORT {at} amibroker.com
>
> TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
> http://www.amibroker.com/feedback/
> (submissions sent via other channels won't be considered)
>
> For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
> http://www.amibroker.com/devlog/
>
> Yahoo! Groups Links
>
>
>
------------------------------------
**** IMPORTANT PLEASE READ ****
This group is for the discussion between users only.
This is *NOT* technical support channel.
TO GET TECHNICAL SUPPORT send an e-mail directly to
SUPPORT {at} amibroker.com
TO SUBMIT SUGGESTIONS please use FEEDBACK CENTER at
http://www.amibroker.com/feedback/
(submissions sent via other channels won't be considered)
For NEW RELEASE ANNOUNCEMENTS and other news always check DEVLOG:
http://www.amibroker.com/devlog/
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