Pyffi: ref procedure

Questions & Answers
1

Where does the ref procedure defined?

i can not find it in the code ,nor in numpy or python and not in the documentation.

It seems used to access a line like in an ndarray:


(define Z (numpy.array '[[0 0 0 0 0 0]
                         [0 0 0 1 0 0]
                         [0 1 0 1 0 0]
                         [0 0 1 1 0 0]
                         [0 0 0 0 0 0]
                         [0 0 0 0 0 0]]))

(ref Z 2)
(obj "ndarray" : array([0, 0, 0, 1, 0, 0]))

i have also defined this:

; getter for ndarray line
(define (ndarray-line-ref A lin)
  (numpy.take A (numpy.array (list lin)) #:axis 0))

(ndarray-line-ref Z 2)
(obj "ndarray" : array([[0, 0, 0, 1, 0, 0]]))

i also wrote a setter for ndarray line, does it already exist something undocumented in pyffi?

2

Look at python-operators.rkt for the definition of ref.

The same file contains :=.

1 Like
3

thank, it escaped my grep on the files.

I read the code fast.

seems ti uses PyObject_GetItem in the lambda-case (never used lambda-case so i could be wrong) ,seems i get the same result with numpy python code.

Will look later := but for now i do not understand where the operator come from, python? ,pyffi? ,scheme? python-C-API? It is hard to trace code between the 3 languages :sweat_smile:

4

Check this table:

If you need a Python operator, the table shows which function to use.
In this case obj[k] is mapped to getitem(obj,k).

5

oh yes i used it years ago before for overloading operators,later with decorator, i had created a sort of type annotation, later type annotation being integrated (not my own implementation) in Python standarts.....
thank