expr.args gives a python tuple of the arguments that can be iterated
through in the normal ways.
>>> for i in (1, 42, 'this'):
... print i
...
1
42
this
>>> expr = 1+x+42/x
>>> for i in expr.args:
... print i
...
1
42/x
x
>>> for i, a in enumerate(expr.args):
... print i, a
...
0 1
1 4
h[1] >>> from sympy.tensor import *
h[1] >>> M=Indexed('M')
h[1] >>> var('i j k', integer=1)
(i, j, k)
h[2] >>> eq=1+2*M(i,1)+3*j+4*M(i,2); eq
1 + 2*M(i, 1) + 3*j + 4*M(i, 2)
h[3] >>> for a in eq.as_Add():
... ie = []
... co = []
... for m in a.as_Mul():
... if isinsta
expr.args gives a python tuple of the arguments that can be iterated
through in the normal ways.
for i in (1, 42, 'this'):
... print i
...
1
42
this
expr = 1+x+42/x
for i in expr.args:
... print i
...
1
42/x
x
for i, a in enumerate(expr.args):
On Thu, Sep 23, 2010 at 2:21 PM, Nicholas Kinar wrote:
>
>> expr.args gives a python tuple of the arguments that can be iterated
>> through in the normal ways.
>>
>>
>
> for i in (1, 42, 'this'):
>
>>
>> ... print i
>> ...
>> 1
>> 42
>> this
>>
>
> expr = 1+x+42/x
> for
Try:
In [166]: expr = 0.5*p(1, 3)**(1 + n)/(x**2*y**2)
In [167]: for n, arg in enumerate(expr.args):
if p(1, 3) in arg:
m = n
break
In [171]: expr.coeff(expr.args[m])
Out[171]: 0.5/(x**2*y**2)
Much appreciated, Andy; thanks for this code snippet. However, what
wo
h[1]>>> from sympy.tensor import *
h[1]>>> M=Indexed('M')
h[1]>>> var('i j k', integer=1)
(i, j, k)
h[2]>>> eq=1+2*M(i,1)+3*j+4*M(i,2); eq
1 + 2*M(i, 1) + 3*j + 4*M(i, 2)
h[3]>>> for a in eq.as_Add():
... ie = []
... co = []
... for m in a.as_Mul():
... if
You should also know about pre/post_order_traversal (both must be imported from
sympy.utilities.iterables), which let you dig all the way down in an expression
tree.
In [109]: from sympy.utilities.iterables import preorder_traversal,
postorder_traversal
In [110]: preorder_traversal(sin(x**2) +
You should also know about pre/post_order_traversal (both must be imported from
sympy.utilities.iterables), which let you dig all the way down in an expression
tree.
In [109]: from sympy.utilities.iterables import preorder_traversal,
postorder_traversal
In [110]: preorder_traversal(sin(x**2
The problem with the is_Foo construct is that every basic has to carry
it, so every object grows. The reason (maybe historic) there are some
there is that its faster to ask is_Foo than to do isinstance a lot and
the core needs some faster things. For bits that aren't checked very
much we should tr
How does the speed compare if you use hasattr()? Also, is there a good reason
that Basic doesn't have __getattr__() implemented?
Aaron Meurer
On Sep 23, 2010, at 7:42 PM, Andy Ray Terrel wrote:
> The problem with the is_Foo construct is that every basic has to carry
> it, so every object grows
On Thu, Sep 23, 2010 at 6:42 PM, Andy Ray Terrel wrote:
> The problem with the is_Foo construct is that every basic has to carry
> it, so every object grows. The reason (maybe historic) there are some
> there is that its faster to ask is_Foo than to do isinstance a lot and
> the core needs some f
How would hasattr help you? It doesn't tell you if there is a
instance of a class in the arg tree only if the instance has a
specific attribute. I guess nobody has needed __getatrr__ yet.
-- Andy
On Thu, Sep 23, 2010 at 8:50 PM, Aaron S. Meurer wrote:
> How does the speed compare if you use ha
Because, if you assume that each class has is_Class set to True for itself, you
can just use getattr(object, 'is_Class', False) (sorry, I meant getattr(), not
hasattr()). For __getattr__, you could set that in Basic and make it recognize
is_Class. I don't know if that will still have the speed
It is supposedly slower. From basic.py:
# NOTE NOTE NOTE
# --
#
# new-style classes + __getattr__ is *very* slow!
# def __getattr__(self, name):
# raise Warning('no way, *all* attribute access will be 2.5x slower')
# here is what we do instead:
fo
to., 23.09.2010 kl. 18.54 -0700, skrev Ondrej Certik:
> On Thu, Sep 23, 2010 at 6:42 PM, Andy Ray Terrel
> wrote:
> > The problem with the is_Foo construct is that every basic has to carry
> > it, so every object grows. The reason (maybe historic) there are some
> > there is that its faster to a
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