Re: [clisp-list] ffi & libsvm

[Sam S. <sd...@gn...>]

if I replace c-array-ptr with c-pointer and write

       (setf (slot (foreign-value ret) 'y) (list-to-vector y)))

it appears to work - but this is somewhat ugly...

Sam Steingold wrote:
> so, what is wrong with this code:
> 
> (def-c-type node (c-struct list (index int) (value double-float)))
> (def-c-type problem (c-struct list
>    (l int)                               ; number of records
>    (y (c-array-ptr double-float))        ; of length l (targets)
>    (x (c-array-ptr (c-array-ptr node))))); of length l (predictors)
> 
> (defun alist-to-nodes (alist)
>    ;; Lisp ((index . value) ...) --> C [index;value]...[-1;*]
>    (let* ((len (length alist))
>           (ret (allocate-shallow 'node :count (1+ len))))
>      (with-c-place (v ret)
>        (loop :for i :upfrom 0 :for (index . value) :in alist :do
>          (setf (slot (element v i) 'index) index
>                (slot (element v i) 'value) value))
>        (setf (slot (element v len) 'index) -1))
>      ret))
> 
> (defun list-to-vector (list)
>    ;; Lisp list --> C array
>    (let* ((len (length list)) (ret (allocate-shallow 'double-float 
> :count len)))
>      (with-c-place (v ret)
>        (loop :for i :upfrom 0 :for value :in list :do
>          (setf (element v i) value)))
>      ret))
> 
> (defun make-problem (&key l y x)
>    (let ((ret (allocate-shallow 'problem)))
>      (setf (slot (foreign-value ret) 'l) l
>            (slot (foreign-value ret) 'y)
>            (offset (foreign-value (list-to-vector y)) 0
>                    `(c-array double-float ,l)) ; FIXME!!
>            (slot (foreign-value ret) 'x)
>            (offset (foreign-value (alist-to-nodes x)) 0
>                    `(c-array (c-ptr node) ,l))) ; FIXME!!
>      ret))
>