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Real life example, when to use OUTER / CROSS APPLY in SQL
I have been looking at CROSS / OUTER APPLY with a colleague and we're struggling to find real life examples of where to use them.
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How to call a Python function from Node.js
...nd child process 1.0.2. The data from python is a byte array and has to be converted. Just another quick example of making a http request in python.
node
const process = spawn("python", ["services/request.py", "https://www.google.com"])
return new Promise((resolve, reject) =>{
process.stdo...
Use JNI instead of JNA to call native code?
...ill perform worse than with JNI. For example when passing arrays, JNA will convert these from Java to native at the beginning of each function call and back at the end of the function call. With JNI, you can control yourself when a native "view" of the array is generated, potentially only creating a...
Arrow operator (->) usage in C
...g a book called "Teach Yourself C in 21 Days" (I have already learned Java and C# so I am moving at a much faster pace). I was reading the chapter on pointers and the -> (arrow) operator came up without explanation. I think that it is used to call members and functions (like the equivalent of...
How to get all subsets of a set? (powerset)
... is 2 ** len(A), so that could clearly be seen in the for loop.
I need to convert the input (ideally a set) into a list because by a set is a data structure of unique unordered elements, and the order will be crucial to generate the subsets.
selector is key in this algorithm. Note that selector ha...
Java 8 Iterable.forEach() vs foreach loop
... if( prev != null )
foo(prev, curr);
prev = curr;
}
Can't handle checked exceptions. Lambdas aren't actually forbidden from throwing checked exceptions, but common functional interfaces like Consumer don't declare any. Therefore, any code that throws checked exceptions must wrap them...
Why does the order of the loops affect performance when iterating over a 2D array?
... are two programs that are almost identical except that I switched the i and j variables around. They both run in different amounts of time. Could someone explain why this happens?
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What integer hash function are good that accepts an integer hash key?
... a multiplier that is in the order of your hash size (2^32 in the example) and has no common factors with it. This way the hash function covers all your hash space uniformly.
Edit: The biggest disadvantage of this hash function is that it preserves divisibility, so if your integers are all divisibl...
get list of pandas dataframe columns based on data type
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As of pandas v0.14.1, you can utilize select_dtypes() to select columns by dtype
In [2]: df = pd.DataFrame({'NAME': list('abcdef'),
'On_Time': [True, False] * 3,
'On_Budget': [False, True] * 3})
In [3]: df.select_dtypes(in...
What is the “right” JSON date format?
...is a non-standard hack/extension.
I would use a format that can be easily converted to a Date object in JavaScript, i.e. one that can be passed to new Date(...). The easiest and probably most portable format is the timestamp containing milliseconds since 1970.
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