Hi,
On 12 November 2011 17:00, [email protected] <
[email protected]> wrote:
> Ok, but why are those printed differently (ipython --profile=sympy):
>
> In [34]: sin(x).func
> Out[34]: sympy.functions.elementary.trigonometric.sin
>
> In [35]: str(sin(x).func)
> Out[35]: sin
>
> In [39]: Integral(x, (x,0,1)).func
> Out[39]: sympy.integrals.integrals.Integral
>
> In [40]: str(Integral(x, (x,0,1)).func)
> Out[40]: <class 'sympy.integrals.integrals.Integral'>
>
> What should I do to have them print in the same manner?
This seems to be a problem with IPython's printing hooks. In CPython I get:
>>> from sympy import *
>>> init_printing()
>>> var('x')
x
>>> sin(x).func
sin
>>> str(sin(x).func)
sin
>>> Integral(x, (x, 0, 1)).func
<class 'sympy.integrals.integrals.Integral'>
>>> str(Integral(x, (x, 0, 1)).func)
<class 'sympy.integrals.integrals.Integral'>
There reason for different output in IPython is that IPython not always
uses SymPy's pretty printer, but sometimes uses its own printing hooks.
It's better visible in the notebook where latex output is used (e.g. try to
print data structures).
>
>
> On 13 November 2011 00:42, Aaron Meurer <[email protected]> wrote:
>
>> Hi.
>>
>> As far as I know, we don't have a function that does exactly that,
>> though I could be wrong. It would be nice to have one, though.
>>
>> On Sat, Nov 12, 2011 at 11:01 AM, Alexey U. Gudchenko <[email protected]>
>> wrote:
>> > 12.11.2011 21:42, [email protected] пишет:
>> >> This:
>> >>
>> >> import ast
>> >> ast.parse(repr(expression))
>>
>> If you want a repr() representation, you should instead use srepr().
>> (repr() is the same as str()).
>>
>> >>
>> >> will do the trick if repr is well coded.
>>
>> str() is coded so that it returns the same thing back from sympify(),
>> but it may not give the same thing directly, because you can have
>> int/int in an expression. srepr() should always give the same thing
>> back.
>>
>> >>
>> >> How much faith should I put in the repr strings in sympy? Or there is
>> >> another way?
>> >>
>> >> On 12 November 2011 18:20, [email protected] <
>> >> [email protected]> wrote:
>> >>
>> >>> Is there any way to get the expression tree from an expression (either
>> >>> using the python abstract syntax tree module or just some tuples):
>> >>>
>> >>> for example
>> >>>
>> >>> get_tree( x+y*sin(z) ) would return
>> >>>
>> >>> (Add, x, (Mul, y, (Sin z)))
>> >>>
>> >>> or
>> >>>
>> >>> (BinOp, Add, ((Symbol, x), (BinOp, Mul, (blah blah blah))))
>> >>>
>> >>
>> >
>> > I know only how to obtain the childes:
>> >
>> >>>> e = x+y*sin(z) + z
>> >>>> e.args
>> > (y*sin(z), z, x)
>> >
>> >>>> e.args[0]
>> >>>> y*sin(z)
>> >
>> >>>> e.args[0].args
>> > (y, sin(z))
>> >
>> >
>> >
>> > And test the classes:
>> >
>> >>>> e.is_Add
>> > True
>> >
>>
>> You can get the class name by using .func:
>>
>> In [25]: e = x + y
>>
>> In [26]: e.func
>> Out[26]: sympy.core.add.Add
>>
>> In [27]: e.func(*e.args)
>> Out[27]: x + y
>>
>> The invariant in [27] should always hold (except for possibly some
>> differences in assumptions).
>>
>> Aaron Meurer
>>
>> >
>> >
>> >
>> > In other words, the somewhat tree of the expressions exists.
>> >
>> > How to represent expression-tree in other formats (strings or
>> > structures), I do not know.
>> >
>> > Regards.
>> >
>> > --
>> > Alexey U.
>> >
>> > --
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>> >
>> >
>>
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>>
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Mateusz
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