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When should I use Struct vs. OpenStruct?
...nstance methods as would a class. A bunch of options for a function, for example, make sense in a hash; they're only loosely related. A name, email, and phone number needed by a function could be packaged together in a Struct or OpenStruct. If that name, email, and phone number needed methods to ...
Calculating moving average
...to use R to calculate the moving average over a series of values in a matrix. The normal R mailing list search hasn't been very helpful though. There doesn't seem to be a built-in function in R will allow me to calculate moving averages. Do any packages provide one? Or do I need to write my own?
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how does multiplication differ for NumPy Matrix vs Array classes?
The numpy docs recommend using array instead of matrix for working with matrices. However, unlike octave (which I was using till recently), * doesn't perform matrix multiplication, you need to use the function matrixmultipy(). I feel this makes the code very unreadable.
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arrayfun can be significantly slower than an explicit loop in matlab. Why?
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You can get the idea by running other versions of your code. Consider explicitly writing out the computations, instead of using a function in your loop
tic
Soln3 = ones(T, N);
for t = 1:T
for n = 1:N
Soln3(t, n) = 3*x(t, n)^2 + 2*x(t, n) - 1;
end
end
toc
Time to compute on my ...
What are some (concrete) use-cases for metaclasses?
... B(A):
... pass
...
>>> models
{'A': <__main__.A class at 0x...>,
'B': <__main__.B class at 0x...>}
This can also be done with class decorators:
models = {}
def model(cls):
models[cls.__name__] = cls
return cls
@model
class A(object):
pass
Or with an expl...
How to join two generators in Python?
....chain() does not return a types.GeneratorType instance. Just in case the exact type is crucial.
– Riga
Sep 16 '19 at 13:45
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Get a list of distinct values in List
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Notes.Select(x => x.Author).Distinct();
This will return a sequence (IEnumerable<string>) of Author values -- one per unique value.
share
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Monad in plain English? (For the OOP programmer with no FP background)
...stem which lets you take a type and turn it into a more special type. For example, in C# consider Nullable<T>. This is an amplifier of types. It lets you take a type, say int, and add a new capability to that type, namely, that now it can be null when it couldn't before.
As a second example, ...
multiple prints on the same line in Python
...can use the print statement to do this without importing sys.
def install_xxx():
print "Installing XXX... ",
install_xxx()
print "[DONE]"
The comma on the end of the print line prevents print from issuing a new line (you should note that there will be an extra space at the end of the out...
Turn a string into a valid filename?
...look at the Django framework for how they create a "slug" from arbitrary text. A slug is URL- and filename- friendly.
The Django text utils define a function, slugify(), that's probably the gold standard for this kind of thing. Essentially, their code is the following.
def slugify(value):
""...