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What is the difference between RDF and OWL? [closed]
...rying to grasp the concept of Semantic Web. I am finding it hard to understand what exactly is the difference between RDF and OWL. Is OWL an extension of RDF or these two are totally different technologies?
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Haskell Type vs Data Constructor
...m learning Haskell from learnyouahaskell.com . I am having trouble understanding type constructors and data constructors. For example, I don't really understand the difference between this:
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Best explanation for languages without null
...deling a door. It can be in one of three states: open, shut but unlocked, and shut and locked. Now I could model it along the lines of
class Door
private bool isShut
private bool isLocked
and it is clear how to map my three states into these two boolean variables. But this leaves a fou...
Moving average or running mean
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UPD: more efficient solutions have been proposed by Alleo and jasaarim.
You can use np.convolve for that:
np.convolve(x, np.ones((N,))/N, mode='valid')
Explanation
The running mean is a case of the mathematical operation of convolution. For the running mean, you slide a win...
What are 'get' and 'set' in Swift?
I'm learning Swift and I'm reading The Swift Programming Language from Apple, I have no Objective C background (only PHP, JS, and other but no Obj C)
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An invalid form control with name='' is not focusable
...runs into the problem of an inaccessible form as one can't submit the form and doesn't get any message from the browser or site. Preventing validation altogether via 'novalidate' is no correct answer as clientside validation should support user inputs. Changing the website is the solution.
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How do I modify fields inside the new PostgreSQL JSON datatype?
...bject('<key>', '<value>')
Where <key> should be string, and <value> can be whatever type to_jsonb() accepts.
For setting a value deep in a JSON hierarchy, the jsonb_set() function can be used:
SELECT jsonb_set('{"a":[null,{"b":[]}]}', '{a,1,b,0}', jsonb '{"c":3}')
-- will yi...
XPath to select multiple tags
...cal-name()='c' or local-name()='d' or local-name()='e']
is both too-long and incorrect. This XPath expression will select nodes like:
OhMy:c
NotWanted:d
QuiteDifferent:e
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What's the difference between a catalog and a schema in a relational database?
... other things--all of the various schemas (external, conceptual, internal) and all of the corresponding mappings (external/conceptual, conceptual/internal) are kept.
In other words, the catalog contains detailed information (sometimes called descriptor information or metadata) regarding the va...
What is the best place for storing uploaded images, SQL database or disk file system? [closed]
...o upload images onto the server. I expect about 20 images per day all jpeg and probably not edited/resized. (This is another question, how to resize the images on the server side before storing. Maybe someone can please drop a .NET resource for that in the comment or so).
I wonder now what the best...