You can see if the parser is modifiable. sympify is more or less just a
pass through on a Python parser, which maps undefined variable names to
Symbols. sympify('2*lambda') doesn't work either, for instance ('lambda' is
a reserved Python keyword).Aaron Meurer On Tue, Dec 30, 2014 at 5:29 PM, Jason Moore <[email protected]> wrote: > Oh I see. I didn't realize you were using sympify. But I don't see > anywhere in the docs that indicates that sympify should understand how to > deal with variable names that include a period. The function that is > failing is: > > > http://docs.sympy.org/dev/modules/parsing.html#sympy.parsing.sympy_parser.parse_expr > > You can customize the parsers if you want to handle different kinds of > string input. > > > Jason > moorepants.info > +01 530-601-9791 > > On Tue, Dec 30, 2014 at 2:39 PM, Andrew Spielberg <[email protected]> > wrote: > >> Hi Jason, >> >> That's true that it's an invalid character for python variables, but not >> for sympy variables. For instance, doing: >> >> s = Symbol('base.length') >> >> works just fine. >> >> I was under the impression that sympify's inputs is treated as a string >> version of a sympy expression, *NOT* a Python expression. This seems to >> be what the documentation implies: >> http://docs.sympy.org/dev/modules/core.html. >> >> Shouldn't this work? I feel like either the documentation is >> misleading/ambiguous or the function is not matching the specification. >> >> Is there a workaround you would recommend that will properly parse >> periods as Symbol does? >> >> -Andy S. >> >> On Tue, Dec 30, 2014 at 1:23 AM, Jason Moore <[email protected]> >> wrote: >> >>> Andy, >>> >>> The period is an invalid character for Python variables. The period is >>> reserved for accessing attributes and methods of Python objects. >>> >>> >>> Jason >>> moorepants.info >>> +01 530-601-9791 >>> >>> On Mon, Dec 29, 2014 at 5:48 PM, Andrew Spielberg <[email protected] >>> > wrote: >>> >>>> Hi guys, >>>> >>>> I have a variable with a period in it (say, 'base.length'). I now wish >>>> to sympify an expression, say: >>>> >>>> 2*base.length >>>> >>>> This throws an exception, >>>> >>>> AttributeError: 'Symbol' object has no attribute 'length' >>>> >>>> due to the period. Is there a way I can have the sympify read the dot >>>> as just part of a variable name here? >>>> >>>> -Andy S. >>>> >>>> -- >>>> You received this message because you are subscribed to the Google >>>> Groups "sympy" group. >>>> To unsubscribe from this group and stop receiving emails from it, send >>>> an email to [email protected]. >>>> To post to this group, send email to [email protected]. >>>> Visit this group at http://groups.google.com/group/sympy. >>>> To view this discussion on the web visit >>>> https://groups.google.com/d/msgid/sympy/CAM6e1JdM%3Dz_vcQkQo%3DLcSVO7oxznXhrVt0U2xQw5GMe8os_R1A%40mail.gmail.com >>>> <https://groups.google.com/d/msgid/sympy/CAM6e1JdM%3Dz_vcQkQo%3DLcSVO7oxznXhrVt0U2xQw5GMe8os_R1A%40mail.gmail.com?utm_medium=email&utm_source=footer> >>>> . >>>> For more options, visit https://groups.google.com/d/optout. >>>> >>> >>> -- >>> You received this message because you are subscribed to the Google >>> Groups "sympy" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/sympy. >>> To view this discussion on the web visit >>> https://groups.google.com/d/msgid/sympy/CAP7f1AizO6eQJd4QwaUFWQssfsnDstKh1v%3DuKo74HF2xgqBL5A%40mail.gmail.com >>> <https://groups.google.com/d/msgid/sympy/CAP7f1AizO6eQJd4QwaUFWQssfsnDstKh1v%3DuKo74HF2xgqBL5A%40mail.gmail.com?utm_medium=email&utm_source=footer> >>> . >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- >> You received this message because you are subscribed to the Google Groups >> "sympy" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To post to this group, send email to [email protected]. >> Visit this group at http://groups.google.com/group/sympy. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/CAM6e1JdwJw52%3D%3DqKFWiSVfMstvwAOO-2vWuvfBfgeTjjp2%3DwSA%40mail.gmail.com >> <https://groups.google.com/d/msgid/sympy/CAM6e1JdwJw52%3D%3DqKFWiSVfMstvwAOO-2vWuvfBfgeTjjp2%3DwSA%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> >> For more options, visit https://groups.google.com/d/optout. >> > > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/sympy. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAP7f1AiEbCSsoBPUZgGTSpxKJwn0r%3DUqpqKeFBVDg6_C1PBVUQ%40mail.gmail.com > <https://groups.google.com/d/msgid/sympy/CAP7f1AiEbCSsoBPUZgGTSpxKJwn0r%3DUqpqKeFBVDg6_C1PBVUQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sympy" group. 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