Re: [matplotlib-devel] spy: ignore zero values in sparse matrix

[Tony S Yu <to...@MI...>]

On Sep 26, 2008, at 2:28 PM, John Hunter wrote:

> On Fri, Sep 26, 2008 at 12:39 PM, Tony S Yu <to...@mi...> wrote:
>
>> +                if all(nonzero == False):
>> +                    raise ValueError('spy cannot plot sparse zeros
>> matrix')
>
> Is raising an exception the right choice here -- why can't we plot an
> all zeros image?
>
> JDH

I guess you could plot sparse all-zero matrices with image mode.  My  
only hesitation is that sparse arrays tend to be very large and (I  
imagine) this would lead to very slow performance. I assumed this was  
the reason image mode wasn't adapted to use sparse arrays.

Actually, now that I think about it: you could plot a trivially small  
image and just adjust the coordinates so that they correspond to the  
original matrix shape. Is this what you were thinking?

I should note that a dense zero array also fails to plot with spy *if  
marker mode is used*.

-T