[Numpy-discussion] profile reveals calls to astype()

Todd Miller jmiller at stsci.edu
Thu Apr 7 10:51:38 CDT 2005


astype() is used in a bunch of places, including the C-API,  so it's
hard to guess how it's getting called with the information here.  In
general,  astype() gets called to "match up types" based on a particular
parameterization of a function call,  i.e.  the c-code underlying some
function call needs a different type than was passed in so astype() is
used to convert an array to a workable type.

One possibility for debugging this might be to drop N to something
reasonable, like say 2,  and then run under pdb with a breakpoint set on
astype().    Something like this is what I have in mind;  it may not be
exactly right but with fiddling this approach might work:

>>> from yourmodule import newfoo  # you redefined foo to accept N as a parameter
>>> import pdb
>>> pdb.run("newfoo(N=2)")
(pdb) s  # step along a little to get into newfoo()
... step output
(pdb) import numarray.numarraycore as nc
(pdb) break nc.astype
(pdb) c
... breakpoint output
(pdb) where
... function traceback showing where astype() got called from
(pdb) c
... breakpoint output
(pdb) where
... more function traceback, eventually you should find it...
...

Regards,
Todd

On Thu, 2005-04-07 at 12:56, Curzio Basso wrote:
> Hi all,
> 
> I have a problem trying to profile a program using numarray, maybe someone with more experience can 
> give me a hint...
> 
> basically, the program I am profiling has a function like this:
> 
> foo():
>    # some code
>    # a call to astype()
>    for i in xrange(N):
>      # some other code and NO explicit call to astype()
> 
> the problem is that when I print the 'callees' of foo(), astype() gets listed with an occurrence of 
> N+1, as if it was called inside the loop.
> So now the first doubt I have is that astype() gets listed because called from some function called 
> by foo(), even if this should not happen. Here is the list of numarray functions called in foo()
> 
> Function                 called...
>                            generic.py:651(getshape)(14)    0.070
>                            generic.py:918(reshape)(2)    0.000
>                            generic.py:1013(where)(2)    0.050
>                            generic.py:1069(concatenate)(2)    4.270
>                            morphology.py:150(binary_erosion)(2)    0.070
>                            numarraycore.py:698(__del__)(120032)    3.240
>                            numarraycore.py:817(astype)(12002)   37.290
>                            numarraycore.py:857(is_c_array)(36000)   10.450
>                            numarraycore.py:878(type)(4)    0.000
>                            numarraycore.py:964(__mul__)(12)    0.340
>                            numarraycore.py:981(__div__)(8)    0.010
>                            numarraycore.py:1068(__pow__)(8)    0.000
>                            numarraycore.py:1180(__imul__)(12000)    0.930
>                            numarraycore.py:1250(__eq__)(2)    0.080
>                            numarraycore.py:1400(zeros)(54)    0.060
>                            numarraycore.py:1409(ones)(8)    0.020
> 
> The second thing I can think of is that astype() is implicitly called by some conversion. Can this be?
> 
> curzio
> 
> 
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