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How do I get the object if it exists, or None if it does not exist?
...odels.Manager, create a safe_get like the code above and use that manager for my models. That way you can write: SomeModel.objects.safe_get(foo='bar').
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R object identification
I am often ending up with a function producing output for which I don't understand the output data type. I'm expecting a list and it ends up being a list of lists or a data frame or something else. What's a good method or workflow for figuring out the output data type when first using a function?
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How can I determine whether a 2D Point is within a Polygon?
I'm trying to create a fast 2D point inside polygon algorithm, for use in hit-testing (e.g. Polygon.contains(p:Point) ). Suggestions for effective techniques would be appreciated.
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Hidden features of mod_rewrite
...ting around lately with a bit of confusion over how certain aspects of it work. As a result I've compiled a few notes on common functionality, and perhaps a few annoying nuances.
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Difference between @OneToMany and @ElementCollection?
...tween using a @OneToMany and @ElementCollection annotation since both work on the one-to-many relationship?
6 Answers
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Variable interpolation in the shell
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Use
"$filepath"_newstap.sh
or
${filepath}_newstap.sh
or
$filepath\_newstap.sh
_ is a valid character in identifiers. Dot is not, so the shell tried to interpolate $filepath_newstap.
You can use set -u to make the shell exit with an error when yo...
How to compare binary files to check if they are the same?
What is the easiest way (using a graphical tool or command line on Ubuntu Linux) to know if two binary files are the same or not (except for the time stamps)? I do not need to actually extract the difference. I just need to know whether they are the same or not.
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How to check if an array field contains a unique value or another array in MongoDB?
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This is well documented in the help: mongodb.org/display/DOCS/…
– Scott Hernandez
Mar 20 '11 at 4:31
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Go > operators
...super (possibly over) simplified definition is just that << is used for "times 2" and >> is for "divided by 2" - and the number after it is how many times.
So n << x is "n times 2, x times". And y >> z is "y divided by 2, z times".
For example, 1 << 5 is "1 times 2, 5...
How can I determine if a String is non-null and not only whitespace in Groovy?
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myString?.trim() returns a string (or null or blank) instead of the question's which returns a boolean. I guess it depends how you're using the output, for just an 'if' it's fine.
– Steven
Feb 7 '12 at 0:31
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