auto_symbol doesn't do namespace injection. It just means that the parser won't fail with a NameError (undefined names in the namespace that the parser users will be converted to Symbols). Your hack works (I would use each_sym.name instead of __str__(), and note that str(each_sym) is the same as each_sym.__str__()).
Aaron Meurer On Wed, Jan 28, 2015 at 4:28 PM, Denis Akhiyarov <[email protected]> wrote: > Can I use parse_expr to parse an expression such as > "a1*x1**2+a2*x1+a3+a4*x1*x2+a5*x2**2" and inject the symbols into globals > or locals namespace? > > Looks like auto_symbol is not doing this. So I have to manually inject > each symbol using sympy.var() method. > > > exp0=parse_expr("a1*x1**2+a2*x1+a3+a4*x1*x2+a5*x2**2",transformations=(auto_number,auto_symbol)) > exp0.subs(a1,10) > > > ---------------------------------------------------------------------------NameError > Traceback (most recent call > last)<ipython-input-4-19dc46bbe490> in <module>()----> 1 exp0.subs(a1,10) > NameError: name 'a1' is not defined > > > > But after my hack: > > for each_sym in exp0.atoms(sympy.Symbol): > sympy.var(each_sym.__str__()) > > > exp0.subs(a1,10) > > 2*x1 + a3 + a4*x1*x2 + a5*x2**2 + 10*x1**2 > > -- > 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/26d01fa4-15fd-45da-b043-9197410f0286%40googlegroups.com > <https://groups.google.com/d/msgid/sympy/26d01fa4-15fd-45da-b043-9197410f0286%40googlegroups.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/CAKgW%3D6%2B5Sqnx%2B%2BPhnScj-S34rfAZQB_BuJK6RTRKPgXGBBvvJA%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
