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how to exclude null values in array_agg like in string_agg using postgres?
If I use array_agg to collect names, I get my names separated by commas, but in case there is a null value, that null is also taken as a name in the aggregate. For example :
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Initialize class fields in constructor or at declaration?
I've been programming in C# and Java recently and I am curious where the best place is to initialize my class fields.
15 An...
efficient circular buffer?
...e an efficient circular buffer in python (with the goal of taking averages of the integer values in the buffer).
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What is the use of the @ symbol in PHP?
I have seen uses of @ in front of certain functions, like the following:
11 Answers
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Can someone explain in simple terms to me what a directed acyclic graph is?
Can someone explain in simple terms to me what a directed acyclic graph is? I have looked on Wikipedia but it doesn't really make me see its use in programming.
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Google Map API V3: How to add Custom data to markers
Is there a way I can add some custom information to my markers for later use. There are ways to have an info-window and a title, but what If I want to associate the marker with other information.
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Setting the correct encoding when piping stdout in Python
When piping the output of a Python program, the Python interpreter gets confused about encoding and sets it to None. This means a program like this:
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Create instance of generic type in Java?
Is it possible to create an instance of a generic type in Java? I'm thinking based on what I've seen that the answer is no ( due to type erasure ), but I'd be interested if anyone can see something I'm missing:
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How to sort git tags by version string order of form rc-X.Y.Z.W?
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7 Answers
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What is the purpose of setting a key in data.table?
I am using data.table and there are many functions which require me to set a key (e.g. X[Y] ). As such, I wish to understand what a key does in order to properly set keys in my data tables.
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