Using a Python list is probably the fastest way to iterate over an array of Python objects--it's a PyObject** under the hood and Cython uses the C API calls to get at it. Your "check" might be the bottleneck, especially if it's a Python call.
Also, no need to write this as a while loop; just use "for a in range(1000000)" and it'll do the right thing (a C for loop). On Wed, Aug 21, 2013 at 12:33 PM, Daniel Krenn <kr...@aon.at> wrote: > I need an array of Elements of RealIntervalField and I want to iterate > (a lot of times) through it. How can I do that in a fast way in Sage's > cython (i.e. in the notebook or in a .spyx-file)? > > An (minimal) example what I basically want is given below (PS). > > I tried the following things (and a lot more) in the Sage notebook as > well as in a .spyx-file: > > > 1. using vector > > from libcpp cimport vector > > gives > > filename.c:317:18: fatal error: vector: file or directory not found > compilation terminated. > error: command 'gcc' failed with exit status 1 > > At least I found the file in Cython/include/... > > > 2. using C arrays > > cimport sage.rings.real_mpfi # do not know whether that is needed... > from sage.rings.real_mpfi cimport RealIntervalFieldElement > cdef RealIntervalFieldElement L[10] > > says > > cdef RealIntervalFieldElement L[10] > ^ > filename.pyx:12:31: Array element cannot be a Python object > > I thought that with cimport I get a C/cython object (but maybe I have > too less understanding of it) > > > 3. using some pointers > > from sage.rings.real_mpfi cimport RealIntervalFieldElement > from sage.all import RIF > cdef void* L[10] > cdef RealIntervalFieldElement r = RIF(100) > L[0] = &r > > gives > > cdef RealIntervalFieldElement r = RIF(100) > L[0] = &r ^ > filename.pyx:15:7: Cannot take address of Python variable > > > I am thankful for any input. > > Daniel > > > PS: Here is what I want faster: > > L = [blabla] # a python list of length about 500 > a=0 > while a<10000000: > b = something(a) > for ell in L: > if check(a,b,ell): > print "yeah" # or do whatever > a += 1 > > L is a list of RealIntervalField elements; b is a RealIntervalElement, too. > > -- > You received this message because you are subscribed to the Google Groups > "sage-support" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sage-support+unsubscr...@googlegroups.com. > To post to this group, send email to sage-support@googlegroups.com. > Visit this group at http://groups.google.com/group/sage-support. > For more options, visit https://groups.google.com/groups/opt_out. -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to sage-support+unsubscr...@googlegroups.com. To post to this group, send email to sage-support@googlegroups.com. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/groups/opt_out.
