I wonder why for me the result is
>>> import_statements(QQ)
# ** Warning **: several names for that object: Q, QQ from
sage.rings.rational_field import Q
On Monday, November 19, 2018 at 4:05:55 AM UTC-8, Dima Pasechnik wrote:
On Mon, Nov 19, 2018 at 11:58 AM John Cremona <john.c...@gmail.com
> <javascript:>> wrote:
> >
> > I recommend importing anything you need from sage.all since the details
> of where everything is might change in time. This works perfectly well:
> >
> > $ sage -python # so we use Sage's python not my system-wide one
> > Python 2.7.15 (default, Nov 2 2018, 14:32:42)
> > [GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux2
> > Type "help", "copyright", "credits" or "license" for more information.
> > >>> from sage.all import PolynomialRing, QQ
> > >>> R = PolynomialRing(QQ,'x')
> > >>> x = R.gen()
> > >>> f = x^3+1 # no good as no preparser
> > Traceback (most recent call last):
> > File "<stdin>", line 1, in <module>
> > File "sage/structure/element.pyx", line 944, in
> sage.structure.element.Element.__xor__
> (build/cythonized/sage/structure/element.c:9006)
> > RuntimeError: Use ** for exponentiation, not '^', which means xor
> > in Python, and has the wrong precedence.
> >
> > # Now we can work with this:
> >
> > >>> f = x**3+1 # that's better
> > >>> f.factor()
> > (x + 1) * (x^2 - x + 1)
> >
> > Another thing I do is to put my commands into a .py file and run
> pyflakes on it, as that reveals what things need to be imported. Then
> import them all from sage.all.
>
> you can also find out exactly what you need to import:
>
> sage: import_statements("QQ")
> from sage.rings.rational_field import QQ
>
>
> >
> > John Cremona
> >
> > On Mon, 19 Nov 2018 at 11:48, Kolen Cheung <christi...@gmail.com
> <javascript:>> wrote:
> >>
> >> Thank you both for the answers. However, I’m still stuck:
> >>
> >> Focusing on just translating the first line: R.<x> = QQ[]
> >>
> >> In sage,
> >>
> >> >>> preparse("R.<x> = QQ[]")
> >> "R = QQ['x']; (x,) = R._first_ngens(1)"
> >> >>> import_statements(QQ)
> >> # ** Warning **: several names for that object: Q, QQ
> >> from sage.rings.rational_field import Q
> >> >>> import_statements(R)
> >> from sage.rings.qqbar import QQx
> >>
> >> Immediately I have a question: how come the import_statements of QQ is
> ... import Q, and the import statement of R is ... import QQx? In either
> case the namespace in question is not imported. Does it mean ... import Q
> as QQ and ... import QQx as R respectively?
> >>
> >> Then I’ve a problem: In sage, I can import them using these import
> statements. But when entering these 2 import statements in Python,
> >>
> >> >>> from sage.rings.rational_field import Q
> >>
> ---------------------------------------------------------------------------
> >> ImportError Traceback (most recent call
> last)
> >> <ipython-input-1-0fb4c40d1a13> in <module>()
> >> ----> 1 from sage.rings.rational_field import Q
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/rational_field.py in
> <module>()
> >> 62 _long_type = int
> >> 63
> >> ---> 64 from .rational import Rational
> >> 65 from .integer import Integer
> >> 66
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/rational.pyx in init
> sage.rings.rational (build/cythonized/sage/rings/rational.c:40976)()
> >> 94
> >> 95
> >> ---> 96 import sage.rings.real_mpfr
> >> 97 import sage.rings.real_double
> >> 98 from libc.stdint cimport uint64_t
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/real_mpfr.pyx in init
> sage.rings.real_mpfr (build/cythonized/sage/rings/real_mpfr.c:44298)()
> >> ----> 1 r"""
> >> 2 Arbitrary Precision Real Numbers
> >> 3
> >> 4 AUTHORS:
> >> 5
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/complex_number.pxd in init
> sage.libs.mpmath.utils (build/cythonized/sage/libs/mpmath/utils.c:8831)()
> >> 4 from .real_mpfr cimport RealNumber
> >> 5
> >> ----> 6 cdef class ComplexNumber(sage.structure.element.FieldElement):
> >> 7 cdef mpfr_t __re
> >> 8 cdef mpfr_t __im
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/complex_double.pxd in init
> sage.rings.complex_number
> (build/cythonized/sage/rings/complex_number.c:24212)()
> >> 8
> >> 9
> >> ---> 10 cdef class ComplexDoubleField_class(sage.rings.ring.Field):
> >> 11 pass
> >> 12
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/complex_double.pyx in init
> sage.rings.complex_double
> (build/cythonized/sage/rings/complex_double.c:24230)()
> >> 96 from cypari2.convert cimport new_gen_from_double,
> new_t_COMPLEX_from_double
> >> 97
> >> ---> 98 from . import complex_number
> >> 99
> >> 100 from .complex_field import ComplexField
> >>
> >> ImportError: cannot import name complex_number
> >> >>> from sage.rings.qqbar import QQx
> >>
> ---------------------------------------------------------------------------
> >> ImportError Traceback (most recent call
> last)
> >> <ipython-input-1-4809457c5588> in <module>()
> >> ----> 1 from sage.rings.qqbar import QQx
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/qqbar.py in <module>()
> >> 512 rich_to_bool,
> richcmp_not_equal,
> >> 513 op_EQ, op_NE)
> >> --> 514 from sage.rings.real_mpfr import RR
> >> 515 from sage.rings.real_mpfi import RealIntervalField, RIF,
> is_RealIntervalFieldElement, RealIntervalField_class
> >> 516 from sage.rings.complex_field import ComplexField
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/real_mpfr.pyx in init
> sage.rings.real_mpfr (build/cythonized/sage/rings/real_mpfr.c:44298)()
> >> ----> 1 r"""
> >> 2 Arbitrary Precision Real Numbers
> >> 3
> >> 4 AUTHORS:
> >> 5
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/complex_number.pxd in init
> sage.libs.mpmath.utils (build/cythonized/sage/libs/mpmath/utils.c:8831)()
> >> 4 from .real_mpfr cimport RealNumber
> >> 5
> >> ----> 6 cdef class ComplexNumber(sage.structure.element.FieldElement):
> >> 7 cdef mpfr_t __re
> >> 8 cdef mpfr_t __im
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/complex_double.pxd in init
> sage.rings.complex_number
> (build/cythonized/sage/rings/complex_number.c:24212)()
> >> 8
> >> 9
> >> ---> 10 cdef class ComplexDoubleField_class(sage.rings.ring.Field):
> >> 11 pass
> >> 12
> >>
> >> /usr/lib/python2.7/site-packages/sage/rings/complex_double.pyx in init
> sage.rings.complex_double
> (build/cythonized/sage/rings/complex_double.c:24230)()
> >> 96 from cypari2.convert cimport new_gen_from_double,
> new_t_COMPLEX_from_double
> >> 97
> >> ---> 98 from . import complex_number
> >> 99
> >> 100 from .complex_field import ComplexField
> >>
> >> ImportError: cannot import name complex_number
> >>
> >> Thanks.
> >>
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