Dumb python questions

kosh kosh at aesaeion.com
Wed Aug 15 02:23:07 CEST 2001


Paul Rubin wrote:

> I just started playing with python and haven't been able to figure
> out the following things from the docs I've found:
> 
> 1) Suppose I have a complex number like a = 3+4j.  How do I get the
> real and imaginary parts separately?  I guess I could say
>    x = (a + a.conjugate())/2
>    y = (a - a.conjugate())/2
> but I can't take this language seriously if that's what the designers
> intended.
> 

>>> a = 3+4j
>>> dir(a)
['conjugate', 'imag', 'real']
>>> a.imag
4.0
>>> a.real
3.0

> 2) Is there a way I can tell if a value is of an integer type?  That is,
>    I want to write a function is_int(x) so that
>      is_int(3) = 1    # 3 is an integer type
>      is_int(3L) = 1   # 3L is an integer type
>      is_int(3.0) = 0  # 3.0 is float type
>      is_int(3+2j) = 0 # 3+2j is complex type
> 

>>> import types
>>> a = 3
>>> isinstance(a, types.IntType)
1
>>> a = 3L
>>> isinstance(a, types.LongType)
1
>>> a = 3.0
>>> isinstance(a, types.FloatType)
1
>>> a = 3+2j
>>> isinstance(a, types.ComplexType)
1

> 3) Are the complex math functions specified to have any particular
>    branch cuts?  If they're unspecified, what happens in the actual cmath
>    implementation?  If they're unspecified, I'd like to propose that the
>    Scheme/Common Lisp conventions be adopted in a future version.

I am not sure what this question is asking so I will leave it to others to 
answer.



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