Re: [Numpy-discussion] Getting Callbacks with arrays to work
Hi, Thanks all works now! The implicit none only didn't work when defining dv as a function now its a subroutine it seems to work. Regards Jon On 12/01/2010 13:44, Pearu Peterson wrote: > Hi, > > The problem is that f2py does not support callbacks that > return arrays. There is easy workaround to that: provide > returnable arrays as arguments to callback functions. > Using your example: > > SUBROUTINE CallbackTest(dv,v0,Vout,N) >IMPLICIT NONE > >!F2PY intent( hide ):: N >INTEGER:: N, ic >EXTERNAL:: dv > >DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 >DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout > >DOUBLE PRECISION, DIMENSION( N ):: Vnow >DOUBLE PRECISION, DIMENSION( N ):: temp > >Vnow = v0 >!f2py intent (out) temp >call dv(temp, Vnow, N) > >DO ic = 1, N > Vout( ic ) = temp(ic) >END DO > > END SUBROUTINE CallbackTest > > $ f2py -c test.f90 -m t --fcompiler=gnu95 > from numpy import * from t import * arr = array([2.0, 4.0, 6.0, 8.0]) def dV(v): > print 'in Python dV: V is: ',v > ret = v.copy() > ret[1] = 100.0 > return ret > ... output = callbacktest(dV, arr) > in Python dV: V is: [ 2. 4. 6. 8.] output > array([ 2., 100.,6.,8.]) > > What problems do you have with implicit none? It works > fine here. Check the format of your source code, > if it is free then use `.f90` extension, not `.f`. > > HTH, > Pearu > > Jon Moore wrote: >> Hi, >> >> I'm trying to build a differential equation integrator and later a >> stochastic differential equation integrator. >> >> I'm having trouble getting f2py to work where the callback itself >> receives an array from the Fortran routine does some work on it and then >> passes an array back. >> >> For the stoachastic integrator I'll need 2 callbacks both dealing with >> arrays. >> >> The idea is the code that never changes (ie the integrator) will be in >> Fortran and the code that changes (ie the callbacks defining >> differential equations) will be different for each problem. >> >> To test the idea I've written basic code which should pass an array back >> and forth between Python and Fortran if it works right. >> >> Here is some code which doesn't work properly:- >> >> SUBROUTINE CallbackTest(dv,v0,Vout,N) >> !IMPLICIT NONE >> >> cF2PY intent( hide ):: N >> INTEGER:: N, ic >> >> EXTERNAL:: dv >> >> DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 >> DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout >> >> DOUBLE PRECISION, DIMENSION( N ):: Vnow >> DOUBLE PRECISION, DIMENSION( N ):: temp >> >> Vnow = v0 >> >> >> temp = dv(Vnow, N) >> >> DO ic = 1, N >> Vout( ic ) = temp(ic) >> END DO >> >> END SUBROUTINE CallbackTest >> >> >> >> When I test it with this python code I find the code just replicates the >> first term of the array! >> >> >> >> >> from numpy import * >> import callback as c >> >> def dV(v): >> print 'in Python dV: V is: ',v >> return v.copy() >> >> arr = array([2.0, 4.0, 6.0, 8.0]) >> >> print 'Arr is: ', arr >> >> output = c.CallbackTest(dV, arr) >> >> print 'Out is: ', output >> >> >> >> >> Arr is: [ 2. 4. 6. 8.] >> >> in Python dV: V is: [ 2. 4. 6. 8.] >> >> Out is: [ 2. 2. 2. 2.] >> >> >> >> Any ideas how I should do this, and also how do I get the code to work >> with implicit none not commented out? >> >> Thanks >> >> Jon >> >> >> >> >> >> ___ >> NumPy-Discussion mailing list >> NumPy-Discussion@scipy.org >> http://mail.scipy.org/mailman/listinfo/numpy-discussion > ___ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
Re: [Numpy-discussion] Getting Callbacks with arrays to work
Hi, The problem is that f2py does not support callbacks that return arrays. There is easy workaround to that: provide returnable arrays as arguments to callback functions. Using your example: SUBROUTINE CallbackTest(dv,v0,Vout,N) IMPLICIT NONE !F2PY intent( hide ):: N INTEGER:: N, ic EXTERNAL:: dv DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout DOUBLE PRECISION, DIMENSION( N ):: Vnow DOUBLE PRECISION, DIMENSION( N ):: temp Vnow = v0 !f2py intent (out) temp call dv(temp, Vnow, N) DO ic = 1, N Vout( ic ) = temp(ic) END DO END SUBROUTINE CallbackTest $ f2py -c test.f90 -m t --fcompiler=gnu95 >>> from numpy import * >>> from t import * >>> arr = array([2.0, 4.0, 6.0, 8.0]) >>> def dV(v): print 'in Python dV: V is: ',v ret = v.copy() ret[1] = 100.0 return ret ... >>> output = callbacktest(dV, arr) in Python dV: V is: [ 2. 4. 6. 8.] >>> output array([ 2., 100.,6.,8.]) What problems do you have with implicit none? It works fine here. Check the format of your source code, if it is free then use `.f90` extension, not `.f`. HTH, Pearu Jon Moore wrote: > Hi, > > I'm trying to build a differential equation integrator and later a > stochastic differential equation integrator. > > I'm having trouble getting f2py to work where the callback itself > receives an array from the Fortran routine does some work on it and then > passes an array back. > > For the stoachastic integrator I'll need 2 callbacks both dealing with > arrays. > > The idea is the code that never changes (ie the integrator) will be in > Fortran and the code that changes (ie the callbacks defining > differential equations) will be different for each problem. > > To test the idea I've written basic code which should pass an array back > and forth between Python and Fortran if it works right. > > Here is some code which doesn't work properly:- > > SUBROUTINE CallbackTest(dv,v0,Vout,N) > !IMPLICIT NONE > > cF2PY intent( hide ):: N > INTEGER:: N, ic > > EXTERNAL:: dv > > DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 > DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout > > DOUBLE PRECISION, DIMENSION( N ):: Vnow > DOUBLE PRECISION, DIMENSION( N ):: temp > > Vnow = v0 > > > temp = dv(Vnow, N) > > DO ic = 1, N > Vout( ic ) = temp(ic) > END DO > > END SUBROUTINE CallbackTest > > > > When I test it with this python code I find the code just replicates the > first term of the array! > > > > > from numpy import * > import callback as c > > def dV(v): > print 'in Python dV: V is: ',v > return v.copy() > > arr = array([2.0, 4.0, 6.0, 8.0]) > > print 'Arr is: ', arr > > output = c.CallbackTest(dV, arr) > > print 'Out is: ', output > > > > > Arr is: [ 2. 4. 6. 8.] > > in Python dV: V is: [ 2. 4. 6. 8.] > > Out is: [ 2. 2. 2. 2.] > > > > Any ideas how I should do this, and also how do I get the code to work > with implicit none not commented out? > > Thanks > > Jon > > > > > > ___ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
[Numpy-discussion] Getting Callbacks with arrays to work
Hi, I'm trying to build a differential equation integrator and later a stochastic differential equation integrator. I'm having trouble getting f2py to work where the callback itself receives an array from the Fortran routine does some work on it and then passes an array back. For the stoachastic integrator I'll need 2 callbacks both dealing with arrays. The idea is the code that never changes (ie the integrator) will be in Fortran and the code that changes (ie the callbacks defining differential equations) will be different for each problem. To test the idea I've written basic code which should pass an array back and forth between Python and Fortran if it works right. Here is some code which doesn't work properly:- SUBROUTINE CallbackTest(dv,v0,Vout,N) !IMPLICIT NONE cF2PY intent( hide ):: N INTEGER:: N, ic EXTERNAL:: dv DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout DOUBLE PRECISION, DIMENSION( N ):: Vnow DOUBLE PRECISION, DIMENSION( N ):: temp Vnow = v0 temp = dv(Vnow, N) DO ic = 1, N Vout( ic ) = temp(ic) END DO END SUBROUTINE CallbackTest When I test it with this python code I find the code just replicates the first term of the array! from numpy import * import callback as c def dV(v): print 'in Python dV: V is: ',v return v.copy() arr = array([2.0, 4.0, 6.0, 8.0]) print 'Arr is: ', arr output = c.CallbackTest(dV, arr) print 'Out is: ', output Arr is: [ 2. 4. 6. 8.] in Python dV: V is: [ 2. 4. 6. 8.] Out is: [ 2. 2. 2. 2.] Any ideas how I should do this, and also how do I get the code to work with implicit none not commented out? Thanks Jon ___ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
