CODEWITHSUNDEEP
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Lancelot
Lancelot

Reputation: 11

how to pass a 3d and 4d numpy.array to swig

I am using python to calculate something, but i want to make it faster. so I used swig.

I want to use a 3d-array and a 4d-array in the same function.

swig.i

%apply (double *INPLACE_ARRAY3, int DIM1, int DIM2, int DIM3)\
{(double *trans, int trans_dim1, int trans_dim2, int trans_dim3)};

%apply (double *INPLACE_ARRAY4, int DIM1, int DIM2, int DIM3, int DIM4)\
{(double *sample,int sam_dim1, int sam_dim2, int sam_dim3, int sam_dim4)};

sample.h

void update_transition(double *trans,int trans_dim1,int trans_dim2, int trans_dim3,
 double *sample,int sam_dim1, int sam_dim2, int sam_dim3, int sam_dim4, double DENO);

but when i use it in python, error:

**TypeError: update_transition() takes exactly 7 arguments (3 given)**

is that means my 3d-array can be recognized by swig, but 4d-array can't? How to solve this problem? I want them both.

Upvotes: 1

Views: 313

Answers (2)

Lancelot
Lancelot

Reputation: 11

Thanks for Schollii's help. It appears because it did not recognize the 4d-array, especially the numpy.i did not implement this part. So I just write a similar one as the 3d-array written in numpy.i , and add numpy.i into makefile.

It works!

Upvotes: 0

Oliver
Oliver

Reputation: 29493

Python is saying that it expects 7 arguments for the function call. The C++ function expects 10. If SWIG were able to apply both these typemaps, the Python function would expect 3, not 7. The only way to go from 10 to 7 is for SWIG to miss the second typemap; so it is able to match your function's first array, but not the second one. To confirm this, use some techniques mentioned on 10.3.6 Debugging typemap pattern matching. Also look at the code generated. One thing you might want to try is a 5-paramater C++ test function that takes a 1D array and a 2D array, export with INPLACE_ARRAY1 and 2 for a 2-parameter Python function. This is a simpler case to solve.

If this doesn't solve problem but gives you useful info, add it to your question and maybe I or others can take another look.

Upvotes: 1

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