It works in 0.7.1:
In [1]: Symbol('x, y')
Out[1]: x, y
In [2]: type(Symbol('x, y'))
Out[2]: sympy.core.symbol.Symbol
In [10]: Symbol("Car[2010, 'prius', 2008]")
Out[10]: Car[2010, 'prius', 2008]
In [11]: type(Symbol("Car[2010, 'prius', 2008]"))
Out[11]: sympy.core.symbol.Symbol
By the way, changing the name of a Symbol after it is created is a bad
idea. It will cause it to compare equal to other symbols of the same
name, but the Symbol's hash will not be updated.
Aaron Meurer
On Sat, Jan 7, 2012 at 12:38 AM, Kevin Hunter <[email protected]> wrote:
> Err, is this perhaps a bug that has been fixed since the 0.7.1 release?
> When I do that, vname can't have commas, else it creates multiple
> variables:
>
> -----
> # For a mnemonic, here is an example variable from a model with which I'm
> # working. The variable format is <VarName>[year, tech, vintage].
>>>> from sympy import *
>>>> assumptions = dict()
>>>> index = (2010, 'Prius', 2008)
>>>> vname = 'Car[%s]' % ','.join(str(i) for i in index)
>
> # I'm looking to create _single_ variable
>>>> v = symbols( vname, **assumptions )
>
> # but instead I get three
>>>> type( v )
> <type 'tuple'>
>>>> len( v )
> 3
>>>> print "Variable 1: '%s'" % v[0]
> Variable 1: 'Car[2010'
>>>> print "Variable 2: '%s'" % v[1]
> Variable 2: 'Prius'
>>>> print "Variable 3: '%s'" % v[2]
> Variable 3: '2008]'
> -----
>
> The only way that I currently know how to get a single variable with commas
> in the name is by updating it's name after it's been created:
>
> -----
>>>> v = symbols( 'some_unique_string', **assumptions )
>>>> v.name = vname
>>>> type( v )
> <class 'sympy.core.symbol.Symbol'>
>>>> len( v )
> Traceback (most recent call last):
> File "<stdin>", line 1, in <module>
> TypeError: object of type 'Symbol' has no len()
>>>> print "Variable 4: '%s'" % v
> Variable 4: 'X[2010,Prius,2008]'
> -----
>
> Does that help elucidate what I'm asking? What I'm looking for is more
> direct method to create variables that have names with commas.
>
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