matplotlib-users

[Matplotlib-users] Fwd: speed of clearing and creating a new array

[Bryan F. <bry...@gm...>]

I am starting with a zero array, populate it according to some
condition, save the graph, and then reset the array to zero.  Can
someone tell me if there is a better (faster) way to do this?  Or am I
just doing that much, and that is how long it will take?  I have a
couple hundred graphs that I am creating, that will ultimately be
combined for animation.

ay=4000
ax=60
#create empty array
a = zeros((ay,ax), int)

while something:
  pcolormesh(X, Y, a)
  figname = 'Frame%03d' %int(field)
  print figname
  savefig(figname)
  # reset values
  a = zeros((ay,ax), int)
  if something:
     if something:
     a[y,x] = a[y,x]+1

Re: [Matplotlib-users] Fwd: speed of clearing and creating a new array

[Eric F. <ef...@ha...>]

Alan G Isaac wrote:
> On Tuesday 08 April 2008 10:46:32 am Bryan Fodness wrote:
>> I am starting with a zero array, populate it according to 
>> some condition, save the graph
> 
> I am going to need something along this line pretty soon.
> What is the difference between matshow and pcolormesh for
> this?  (Besides the aspect ratio?)

matshow is a compatibility interface to imshow, which is restricted to 
regular rectangular grids, but is the fastest way to make an image-like 
plot.  pcolormesh is not as fast, but can handle arbitrary quadrilateral 
grids. There is also code to handle irregular rectangular grids at a 
speed intermediate between imshow and pcolormesh (which is a wrapper for 
quadmesh).

A unified interface to all of these is provided by the pcolorfast axes 
method in svn.  Its API may need tweaking; suggestions are welcome.

Eric

> 
> Thank you,
> Alan Isaac
> 
> 
> 
> 
> 
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Re: [Matplotlib-users] Fwd: speed of clearing and creating a new array

[Darren D. <dar...@co...>]

On Tuesday 08 April 2008 10:46:32 am Bryan Fodness wrote:
> I am starting with a zero array, populate it according to some
> condition, save the graph, and then reset the array to zero.  Can
> someone tell me if there is a better (faster) way to do this?

You might ask at the numpy mailing list, but I suspect that 

a *= 0

might be faster.

> Or am I 
> just doing that much, and that is how long it will take?  I have a
> couple hundred graphs that I am creating, that will ultimately be
> combined for animation.
>
> ay=4000
> ax=60
> #create empty array
> a = zeros((ay,ax), int)
>
> while something:
>   pcolormesh(X, Y, a)
>   figname = 'Frame%03d' %int(field)
>   print figname
>   savefig(figname)
>   # reset values
>   a = zeros((ay,ax), int)
>   if something:
>      if something:
>      a[y,x] = a[y,x]+1

Re: [Matplotlib-users] Fwd: speed of clearing and creating a new array

[Alan G I. <ai...@am...>]

On Tuesday 08 April 2008 10:46:32 am Bryan Fodness wrote:
> I am starting with a zero array, populate it according to 
> some condition, save the graph

I am going to need something along this line pretty soon.
What is the difference between matshow and pcolormesh for
this?  (Besides the aspect ratio?)

Thank you,
Alan Isaac

Re: [Matplotlib-users] Fwd: speed of clearing and creating a new array

[Pierre GM <pgm...@gm...>]

On Tuesday 08 April 2008 10:46:32 Bryan Fodness wrote:
> I am starting with a zero array, populate it according to some
> condition, save the graph, and then reset the array to zero.  Can
> someone tell me if there is a better (faster) way to do this? 

My 2c:

* Use inplace addition to save some space

while something:
    ....
    if something:
        if something:
        a[y,x] += 1

* To set all the values to 0:
a.flat = 0