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Add note about memory layout in .to_owned() docs #442

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merged 1 commit into from
May 4, 2018
Merged

Add note about memory layout in .to_owned() docs #442

merged 1 commit into from
May 4, 2018

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jturner314
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Questions:

  • Is this the right place to put this?
  • Can we improve upon these example implementations? They're pretty verbose.

@jturner314 jturner314 mentioned this pull request Apr 27, 2018
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@ExpHP
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ExpHP commented Apr 27, 2018

My feelings:

  • to_owned is one of the places I looked; I think it is a good location
    • This location has the advantage of also being to describe Fortran layout, which wouldn't work so well on is_standard_layout
  • I'm also glad that it includes the search phrase "standard layout"

I would consider #441 to be solved by this.

bluss
bluss reviewed Apr 27, 2018
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src/impl_methods.rs Outdated
/// If you need a particular layout, you can allocate a new array with the
/// desired memory layout and [`.assign()`](#method.assign) the data.
/// Alternatively, you can collect an iterator, like this for a result in
/// standard layout:
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This can be fine as a contract, but I don't really agree with it. The layout of the output should be the same as that of the input, if possible. Then we restrict and say it's only possible if the input is contiguous (which is more or less true). Then yes, that's not entirely correct with the current implementation, since not all contiguous arrays are covered right now (but most..).

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Okay, how about

If the input array is contiguous and its strides are positive, then the output array will have the same memory layout. Otherwise, the layout of the output array is unspecified. If you need a particular layout…

As far as I can tell, this description matches the current implementation. Once we add support for negative strides in .is_contiguous(), we can remove the "strides are positive" constraint.

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Yes that's good

@jturner314 jturner314 force-pushed the more-to-owned-docs branch from c39954c to 8c003b0 Compare May 4, 2018 02:25
@jturner314 jturner314 merged commit 98d20ef into rust-ndarray:master May 4, 2018
@jturner314 jturner314 deleted the more-to-owned-docs branch May 4, 2018 02:42
@Enet4 Enet4 mentioned this pull request Jul 24, 2018
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@jturner314 @ExpHP @bluss