Repository navigation
Add head(), tail() and thin() methods? #319
Description
These would be shortcuts for isel/slice syntax:
ds.head(time=5)->ds.isel(time=slice(5)): select the first five time valuesds.tail(time=5)->ds.isel(time=slice(-5, None)): select the last five time valuesds.thin(time=5)->ds.isel(time=slice(None, None, 5)): select every 5th time value
Activity
ebrevdo commentedon Feb 11, 2015
Clojure conventions: .take, .take_last get the first n and last n
pandas/ndarray conventions: .take([3,4,5]) selects rows 3,4,5.
probably want to be consistent with one of these.
On Tue, Feb 10, 2015 at 3:28 PM, Stephan Hoyer notifications@github.com
wrote:
shoyer commentedon Feb 11, 2015
@ebrevdo yes, I think we probably need to stick to the pandas/numpy convention for the meaning of
take.My inspiration for these names was the
head()andtail()methods in pandas, which are quite convenient. But it's not entirely clear how/if these generalize cleanly to N-dimensions. I supposetake_firstandtake_lastcould be an improvement overhead/tail.ebrevdo commentedon Feb 11, 2015
seems like for, e.g., head, you can pass either a single dimension or
multiple ones (e.g., either as **kwargs or a dictionary) and use those as
the start dimension.
that said, about naming conventions, i think for tensors the most common
convention is definitely slice() (which is implemented as isel). head/tail
can be implemented in terms of slice().
e.g.:
ds.slice(dim1=3, dim2=(1,4), dim3=(1,None,5)) -- or --
ds.slice({'dim1': 3, 'dim2': (1,4), 'dim3': (1, None, 5)})
head/tail/whatever are easy calls to this and you can have that in the
documentation. as a result, people won't get confused because they
understand slice.
On Tue, Feb 10, 2015 at 4:14 PM, Stephan Hoyer notifications@github.com
wrote:
[-]Add head(), tail() and subsample() methods[/-][+]Add head(), tail() and subsample() methods?[/+][-]Add head(), tail() and subsample() methods?[/-][+]Add head(), tail() and thin() methods?[/+]stale commentedon Feb 1, 2019
In order to maintain a list of currently relevant issues, we mark issues as stale after a period of inactivity
If this issue remains relevant, please comment here or remove the
stalelabel; otherwise it will be marked as closed automaticallyjhamman commentedon Feb 2, 2019
I think this is still worth doing. I actually prefer @shoyer's original method names and API. I also think this would be a good first issue.
shoyer commentedon Feb 2, 2019
One virtue of tail() is particular is that we can define
array.tail(x=0)to consistently return an array with an x dimension of size 0. This requires special case logic with slicing, since slice(None, -0) is the same as slice(None, 0).shoyer commentedon Feb 2, 2019
Anyways so yes, I agree that these would definitely be more readable than the equivalent operations with isel().
HasanAhmadQ7 commentedon Aug 5, 2019
Will work on this issue in the next three weeks if no one else does till then.
griverat commentedon Sep 3, 2019
Is this being worked on?
If not, I can send a PR today since I have some code ready that might help add this functionality.
dcherian commentedon Sep 3, 2019
Go for it!