Re: [python-control-discuss] __repr__

[Ryan K. <rk...@si...>]

> >>> h

> TransferFunction([1], [1, 2, 1])


This would be a big improvement in my mind and seems simple to implement.




--
Ryan Krauss, Ph.D.
Associate Professor
Mechanical Engineering
Southern Illinois University Edwardsville


On Wed, Jun 12, 2013 at 2:16 AM, Rene van Paassen <ren...@gm...
> wrote:

> Numpy does this:
>
> Imported NumPy 1.6.2, SciPy 0.10.1, Matplotlib 1.0.1
> Type "scientific" for more details.
> >>> import numpy as np
> >>> x = np.arange(0, 9)
> >>> x
> array([0, 1, 2, 3, 4, 5, 6, 7, 8])
> >>> y = array([0, 1, 2, 3, 4, 5, 6, 7, 8])
> >>> y
> array([0, 1, 2, 3, 4, 5, 6, 7, 8])
> >>> print x
> [0 1 2 3 4 5 6 7 8]
>
> But for big arrays
>
> >>> y = np.arange(0, 100, 0.01)
>
>
> >>> y
>
> array([ 0.00000000e+00, 1.00000000e-02, 2.00000000e-02, ...,
>
>          9.99700000e+01, 9.99800000e+01, 9.99900000e+01])
>
>
> I guess for python-control the proper thing is something like:
>
>
> >>> h
>
> TransferFunction([1], [1, 2, 1])
>
>
> I wouldn't have known the distinction between __repr__ and __str__ either,
> but stumbled upon it since I am currently teaching python to 1st year
> undergrads. I also teach control theory to 2nd year, of which a quarter is
> using Python (from last year's Python programming trial) and the rest is
> using Matlab.
>
>
> René
>
>
> Associate Professor
>
> Aerospace Engineering
>
> Delft University of Technology
>
>
> On 12 June 2013 04:26, Ryan Krauss <rk...@si...> wrote:
>
>> > __repr__ is ideally for printing a representation that can directly be
>> fed back into Python to > re-create the object.
>>
>> I guess I didn't realize this convention.  Like you said, I don't think
>> it is typically followed.  When I want to look at a variable at the IPython
>> prompt, I am not used to having to type print in front of it.
>>
>>
>> --
>> Ryan Krauss, Ph.D.
>> Associate Professor
>> Mechanical Engineering
>> Southern Illinois University Edwardsville
>>
>>
>> On Tue, Jun 11, 2013 at 2:37 PM, Rene van Paassen <
>> ren...@gm...> wrote:
>>
>>> __str__ is for pretty printing
>>> __repr__ is ideally for printing a representation that can directly be
>>> fed back into Python to re-create the object. Many objects don't implement
>>> that, though, it is basically limited to the standard Python objects.
>>>
>>>
>>> On 10 June 2013 17:53, Ryan Krauss <rk...@si...> wrote:
>>>
>>>> I probably won't get to this one for a few weeks (I have a conference
>>>> and another paper coming up), but I would like to contribute a __repr__
>>>> method for TransferFunctions if it would be welcome.  I personally would
>>>> prefer that when I type the name of a TransferFunction instance and hit
>>>> enter that it pretty print an ascii numerator and denominator and a
>>>> horizontal line.  It might be tricky to do it really nicely with exponents,
>>>> but this is what happend now:
>>>>
>>>> In [2]: G = control.TransferFunction(1,[1,2])
>>>>
>>>> In [3]: G
>>>> Out[3]: <control.xferfcn.TransferFunction instance at 0x10e94cf80>
>>>>
>>>> I then have to ask ro G.num and G.den separately, which I personally
>>>> don't like.
>>>>
>>>> I see that there is a __str__ method which pretty much does what I
>>>> would want, so that "print G" gives me an ascii representation.
>>>>
>>>> Is there any reason not to have __repr__ simply call __str__?  Is there
>>>> some historical reason to have one and not the other?
>>>>
>>>> --
>>>> Ryan Krauss, Ph.D.
>>>> Associate Professor
>>>> Mechanical Engineering
>>>> Southern Illinois University Edwardsville
>>>>
>>>>
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>>>
>>>
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> René van Paassen        | ______o____/_|     Ren...@gm...
>                        <[___\_\_-----<               t: +31 15 2628685
>                         |  o'                   mobile: +31 6 39846891
>
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