Re: SWIG typemap for ta-lib

On Mar 14, 11:45 am, "BENI" <rajib.chakraba...@xxxxxxxxxxxxxx> wrote:
Thanks for your lead.
It is lot clear now ... how to go about it.
Still I am fuzzy on a couple of things.
Could you pl guide....



in ruby use it as
closePrice = Array.new(<your data>)
data_inp = closePrice[0..399]
data_arr = ModuleExp::TA_MA( data_inp, 30, ModuleExp::TA_MAType_SMA)

So are you suggesting that i need not pass startIdx,endIdx in the
input. But these values I understand is required .. this is to
sometimes specify a range on which to run the function .
What I am confused about is ...ModuleExp::TA_MAType_SMA... is this a
constant that you are suggesting to pass along?





In .i file you should define
%typemap(in)(int startIdx,
int endIdx,
const double inReal[]
)
{

Check_Type($input, T_ARRAY);

/* Get the length of the array */
int size = RARRAY($input)->len;
int i;
$3 = (unsigned char*) malloc(size * sizeof(double));
$2 = size;
$1 = 0;

// copy the ruby array in the new allocated buffer
/* Get the first element in memory */
VALUE *ptr = RARRAY($input)->ptr;
for (i=0; i < size; i++, ptr++)
{
/* Convert Ruby Object Fixnum to unsigned char */
$1[i]= (double)?????(*ptr); // here i don't remember the macro
to convert something like FIX2INT for float
}

here I used $1[i]= NUM2DBL(*ptr);
is that OK?

}

%typemap(in)(int optInMAType,
int *outBegIdx,
int *outNbElement,
double outReal[]
)
{
int out_beg_ix = 0;
int out_n_ele = 0;
double arr_res[400];

Here I need to dimensionise the arr_res to the size of the input
array instead of 400. So i need to get the size variable in the
previous typemap declaration. But how can i use the size variable
here... it was a local variable only.





$1 = NUM2INT(optInMAType);
$2 = &out_beg_ix;
$3 = &out_n_ele;
&4 = arr_res;

}

%typemap(freearg) (int startIdx,
int endIdx,
const double inReal[],
int optInTimePeriod,
int optInMAType,
int *outBegIdx,
int *outNbElement,
double outReal[]) {
free((double *) $1);
}

%typemap(out)TA_RetCode TA_MA( int startIdx,
int endIdx,
const double inReal[],
int optInTimePeriod,
int optInMAType,
int *outBegIdx,
int *outNbElement,
double outReal[])

I did not get this one clearly.... TA_Retcode is the output type.
Can't i get it in ruby?Only thing that i am getting back here is the
outReal[] array i think.

{

int iStartIx = *arg6;
int iLen = iStartIx + *arg7;

VALUE arr = rb_ary_new2(iLen);

for ( int i = iStartIx; i < iLen; i++ )
rb_ary_push(arr, INT2FIX((*arg8)[i]));
$result = arr;

the *arg8 contains floating point number so will INT2FIX work?

}

it is not tested but this give you the idea how to make the i file.

Regards

Thanks again ..

Regards

Sorry for some errors.
Your questions.
If you use TA_MAType_SMA in the C function and you want to use it
also in ruby, you have to export it.
In Ruby I like to use all input parameters as function parameters.
Out parameters on the left side as result. If you are also interested
an TA_Retcode you have to change the typemap(out). Afterwards you can
use in ruby this:
ta_res, data_arr_out = ModuleExp::TA_MA( data_inp, 30,
ModuleExp::TA_MAType_SMA)

in .i file:
%typemap(out)TA_RetCode TA_MA( int startIdx,
int endIdx,
const double inReal[],
int optInTimePeriod,
int optInMAType,
int *outBegIdx,
int *outNbElement,
double outReal[]
{

int iStartIx = *arg6;
int iLen = iStartIx + *arg7;
VALUE arr_results = rb_ary_new2(2) // 2 elements as result
rb_ary_push(arr_results, INT2FIX(result)); // first is
TA_Retcode

VALUE arr_data = rb_ary_new2(iLen); // data array

for ( int i = iStartIx; i < iLen; i++ )
rb_ary_push(arr_data, rb_float_new((*arg8)[i]));

rb_ary_push(arr_results, arr_data); // second array of data

$result = arr_results

}

here you are right, INT2FIX doesn't work but rb_float_new should be.
NUM2DBL for inputs should be also ok.

If you need to pass startIdx,endIdx as input, you have to modify the
typemap(in)

%typemap(in)(const double inReal[])
{

Check_Type($input, T_ARRAY);

/* Get the length of the array */
int size = RARRAY($input)->len;
int i;
$1 = (unsigned char*) malloc(size * sizeof(double));

// copy the ruby array in the new allocated buffer
/* Get the first element in memory */
VALUE *ptr = RARRAY($input)->ptr;
for (i=0; i < size; i++, ptr++)
{
/* Convert Ruby Object Fixnum to unsigned char */
$1[i]= (double)NUM2DBL(*ptr);
}
}

If you don't like a maxsize for output array, like double
arr_res[MAX_OUT_DATA];
you can use:
arg8 = (unsigned char*) malloc(size * sizeof(double));
inside %typemap(in)(const double inReal[])
I don't know if it is exact, but you can look inside the generated
code if all is set like you want (I use swig with c++ and I expect a
function called _wrap_TA_MA inside generated code).
Don't forget to free arg8 in the typemap.

Cheers
Igor




.

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