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What's the difference between a continuation and a callback?
...ghtenment about continuations, and it's mind boggling how the simplest of explanations can so utterly confound a JavaScript programmer like myself. This is especially true when most articles explain continuations with code in Scheme or use monads.
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Remove all the elements that occur in one list from another
...List Comprehensions that is perfectly suited to making this sort of thing extremely easy. The following statement does exactly what you want and stores the result in l3:
l3 = [x for x in l1 if x not in l2]
l3 will contain [1, 6].
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List comprehension vs. lambda + filter
...le (value). That is slower than accessing a local variable and in Python 2.x the list comprehension only accesses local variables. If you are using Python 3.x the list comprehension runs in a separate function so it will also be accessing value through a closure and this difference won't apply.
The...
One-line list comprehension: if-else variants
It's more about python list comprehension syntax. I've got a list comprehension that produces list of odd numbers of a given range:
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Log to the base 2 in python
... <built-in function log>
Namespace: Interactive
Docstring:
log(x[, base]) -> the logarithm of x to the given base.
If the base not specified, returns the natural logarithm (base e) of x.
In [25]: math.log(8,2)
Out[25]: 3.0
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surface plots in matplotlib
...ays.
If all you have is a list of 3d points, rather than some function f(x, y) -> z, then you will have a problem because there are multiple ways to triangulate that 3d point cloud into a surface.
Here's a smooth surface example:
import numpy as np
from mpl_toolkits.mplot3d import Axes3D
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Pandas every nth row
...umn slice, both based on integer position and following normal python syntax.
df.iloc[::5, :]
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Object comparison in JavaScript [duplicate]
...ursively and access all non-enumerable properties, but this works in Firefox only.
So the best I can do is to guess usage scenarios.
1) Fast and limited.
Works when you have simple JSON-style objects without methods and DOM nodes inside:
JSON.stringify(obj1) === JSON.stringify(obj2)
The OR...
Accessing class variables from a list comprehension in the class definition
...ss scope and list, set or dictionary comprehensions, as well as generator expressions do not mix.
The why; or, the official word on this
In Python 3, list comprehensions were given a proper scope (local namespace) of their own, to prevent their local variables bleeding over into the surrounding sc...
Geometric Mean: is there a built-in?
...ulating geometric mean in R. The verbose mean calculation involving length(x) is necessary for the cases where x contains non-positive values.
gm_mean = function(x, na.rm=TRUE){
exp(sum(log(x[x > 0]), na.rm=na.rm) / length(x))
}
Thanks to @ben-bolker for noting the na.rm pass-through and @Gr...