DOC: Created an explanation document for copies and views #19791
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Thank you for your comments @melissawm! I will make these improvements. |
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@rossbar want to give a quick look? |
doc/source/user/basics.copies.rst
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| How to tell if the array is a view or a copy | ||
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| The :attr:`base <.ndarray.base>` attribute of the ndarray makes it easy | ||
| to tell if an array is a view or a copy. The base attribute of a view returns | ||
| the original array while for a copy it returns ``None``. | ||
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| >>> x = np.arange(9) | ||
| >>> x | ||
| array([0, 1, 2, 3, 4, 5, 6, 7, 8]) | ||
| >>> y = x.reshape(3, 3) | ||
| >>> y | ||
| array([[0, 1, 2], | ||
| [3, 4, 5], | ||
| [6, 7, 8]]) | ||
| >>> y.base # .reshape() creates a view | ||
| array([0, 1, 2, 3, 4, 5, 6, 7, 8]) | ||
| >>> z = y[[2, 1]] | ||
| >>> z | ||
| array([[6, 7, 8], | ||
| [3, 4, 5]]) | ||
| >>> z.base is None # advanced indexing creates a copy | ||
| True |
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It doesn't have to be for this PR, but I think it would be very useful to have a section above this that highlights what sort of operations create copies/views.
The example here has two nice demonstrations of this: reshaping and advanced indexing creating views/copies, respectively. IMO it would be beneficial to highlight these and explain why - in fact I think this should be the main emphasis of this document!
For example, I would move the indexing section and reshaping sections above this one.
This is mostly subjective though - these organizational ideas aren't blockers and we could handle them in followup PRs
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Thanks for the suggestions @rossbar; I like them!
I wanted this to be the main focus too but I haven't found many resources to understand this concept. The ones I have read (links in the description above), mostly talk about indexing. Do you have any sources or maybe someone who could enlighten me? |
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The rendered page is here. I rebased my branch but the build is still failing for some reason. |
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Not sure why, but in any case it's not related to your work here. |
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Thanks @Mukulikaa. The page looks great. If any tweaks are needed they can be done in follow-on PRs. |
This is an attempt to address issue #15793 by creating an explanation document about copies and views in NumPy. I would appreciate suggestions and feedback on how to do justice to this topic and any additional resources. The references specific to this topic that I found useful are:
cc: @melissawm @rossbar