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Why do people say there is modulo bias when using a random number generator?
...AND_MAX is 10 and I decide to generate a random number between 0 and 2 by calling rand()%3. However, rand()%3 does not produce the numbers between 0 and 2 with equal probability!
When rand() returns 0, 3, 6, or 9, rand()%3 == 0. Therefore, P(0) = 4/11
When rand() returns 1, 4, 7, or 10, rand()%3 ...
List all sequences in a Postgres db 8.1 with SQL
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The following query gives names of all sequences.
SELECT c.relname FROM pg_class c WHERE c.relkind = 'S';
Typically a sequence is named as ${table}_id_seq. Simple regex pattern matching will give you the table name.
To get last value of a sequence use the ...
Is it possible to declare two variables of different types in a for loop?
...and clang for years (since gcc-7 and clang-4.0) (clang live example). This allows us to unpack a tuple like so:
for (auto [i, f, s] = std::tuple{1, 1.0, std::string{"ab"}}; i < N; ++i, f += 1.5) {
// ...
}
The above will give you:
int i set to 1
double f set to 1.0
std::string s set to "...
Android Layout with ListView and Buttons
...rwise, the layout is not aware of the Buttons yet because it reads them in order, which is why your ListView extends past them.
– Tim H
Mar 6 '10 at 1:54
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Selecting/excluding sets of columns in pandas [duplicate]
...-based method, so duplicate column names will cause issues, and the column order may be changed.
Advantage over drop: you don't create a copy of the entire dataframe when you only need the list of columns. For instance, in order to drop duplicates on a subset of columns:
# may create a copy of t...
How do you do Impersonation in .NET?
...asy
WindowsIdentity.Impersonate Method (check out the code samples)
Basically you will be leveraging these classes that are out of the box in the .NET framework:
WindowsImpersonationContext
WindowsIdentity
The code can often get lengthy though and that is why you see many examples like the on...
What are OLTP and OLAP. What is the difference between them?
...storical data) use OLAP
if you are doing transactions (ex. adding/removing orders on an e-commerce cart) use OLTP
Short answer:
Let's consider two example scenarios:
Scenario 1:
You are building an online store/website, and you want to be able to:
store user data, passwords, previous transact...
How to use orderby with 2 fields in linq? [duplicate]
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MyList.OrderBy(x => x.StartDate).ThenByDescending(x => x.EndDate);
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“Order by Col1, Col2” using entity framework
I need to order by 2 columns using the entity framework.
5 Answers
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How to check whether an object has certain method/property?
...much any modern dynamic scripting language (Python, Javascript, VB script, PHP, Lua... I could go on and on). It's not a bug, it's a feature.
– Tim Keating
Dec 3 '11 at 14:36
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