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Can Python print a function definition?
...tsource(re.compile)
def compile(pattern, flags=0):
"Compile a regular expression pattern, returning a pattern object."
return _compile(pattern, flags)
This will work in the interactive prompt, but apparently only on objects that are imported (not objects defined within the interactive pro...
Reduce, fold or scan (Left/Right)?
...ach element of a collection. The result of each step is passed on to the next step (as input to one of the binary operator's two arguments). This way we can cumulate a result.
reduceLeft and reduceRight cumulate a single result.
foldLeft and foldRight cumulate a single result using a start value.
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Is there a standard sign function (signum, sgn) in C/C++?
...u need to promote and then narrow again. This is branchless and optimizes excellently
Standards-compliant! The bitshift hack is neat, but only works for some bit representations, and doesn't work when you have an unsigned type. It could be provided as a manual specialization when appropriate.
Accura...
How does python numpy.where() work?
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How do they achieve internally that you are able to pass something like x > 5 into a method?
The short answer is that they don't.
Any sort of logical operation on a numpy array returns a boolean array. (i.e. __gt__, __lt__, etc all return boolean arrays where the given condition is true).
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Representing and solving a maze given an image
...y), adjusting weights for the colors so that final grayscale image is approximately uniform. You can do it simply by controlling sliders in Photoshop in Image -> Adjustments -> Black & White.
Convert image to binary by setting appropriate threshold in Photoshop in Image -> Adjustments -...
John Carmack's Unusual Fast Inverse Square Root (Quake III)
...uake III source code which calculates the inverse square root of a float, 4x faster than regular (float)(1.0/sqrt(x)) , including a strange 0x5f3759df constant. See the code below. Can someone explain line by line what exactly is going on here and why this works so much faster than the regular im...
data.table vs dplyr: can one do something well the other can't or does poorly?
..., not so much with dplyr . I've read through some dplyr vignettes and examples that have popped up on SO, and so far my conclusions are that:
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Which is more preferable to use: lambda functions or nested functions ('def')?
...r for an assignment, so the result is the same, and they are a lot more flexible and readable.
lambdas can be used for use once, throw away functions which won't have a name.
However, this use case is very rare. You rarely need to pass around unnamed function objects.
The builtins map() and filte...
How to make an array of arrays in Java
... String[][] { array1, array2, array3, array4, array5 };
(The latter syntax can be used in assignments other than at the point of the variable declaration, whereas the shorter syntax only works with declarations.)
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Search and replace in bash using regular expressions
I've seen this example:
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