python - NumPy slice notation in a dictionary -

i wonder if possible store numpy slice notation in python dictionary. like:

lookup = {0:[:540],           30:[540:1080],           60:[1080:]} 

it possible use native python slice syntax, e.g. slice(0,10,2), have not been able store more complex slices. example, multidimensional [:,:2,:, :540].

my current work around store values tuples , unpack these necessary slices.

working in python 2.x.

the syntax [:, :2, :, :540] turned tuple of slice objects python:

(slice(none, none, none),  slice(none, 2, none),  slice(none, none, none),  slice(none, 540, none)) 

a convenient way generate tuple use special function* np.s_. need pass [...] expression. example:

>>> np.s_[:540] slice(none, 540, none) >>> np.s_[:, :2, :, :540] (slice(none, none, none),  slice(none, 2, none),  slice(none, none, none),  slice(none, 540, none)) 

then dictionary of slices written as:

lookup = {0: np.s_[:540],           30: np.s_[540:1080],           60: np.s_[1080:]} 

* technically s_ alias class indexexpression implements special __getitem__ method.