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How to use filter, map, and reduce in Python 3
filter , map , and reduce work perfectly in Python 2. Here is an em>x m>ample:
7 Answers
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Sort a list by multiple attributes?
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A key can be a function that returns a tuple:
s = sorted(s, key = lambda m>x m>: (m>x m>[1], m>x m>[2]))
Or you can achieve the same using itemgetter (which is faster and avoids a Python function call):
import operator
s = sorted(s, key = operator.itemgetter(1, 2))
And notice that here you can use sort inst...
Equation for testing if a point is inside a circle
If you have a circle with center (center_m>x m>, center_y) and radius radius , how do you test if a given point with coordinates (m>x m>, y) is inside the circle?
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How can we make m>x m>kcd style graphs?
Apparently, folk have figured out how to make m>x m>kcd style graphs in Mathematica and in LaTem>X m> . Can we do it in R? Ggplot2-ers? A geom_m>x m>kcd and/or theme_m>x m>kcd?
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Simultaneously merge multiple data.frames in a list
...icate of this one so I answer here, using the 3 sample data frames below:
m>x m> <- data.frame(i = c("a","b","c"), j = 1:3, stringsAsFactors=FALSE)
y <- data.frame(i = c("b","c","d"), k = 4:6, stringsAsFactors=FALSE)
z <- data.frame(i = c("c","d","a"), l = 7:9, stringsAsFactors=FALSE)
Update ...
Callback functions in C++
...s of the standard algorithms library <algorithm> use callbacks. For em>x m>ample the for_each algorithm applies an unary callback to every item in a range of iterators:
template<class InputIt, class UnaryFunction>
UnaryFunction for_each(InputIt first, InputIt last, UnaryFunction f)
{
for (...
Generic type parameter naming convention for Java (with multiple chars)?
...name.
The most commonly used type parameter names are:
E - Element (used em>x m>tensively by the Java Collections Framework)
K - Key
N - Number
T - Type
V - Value
S,U,V etc. - 2nd, 3rd, 4th types
You'll see these names used throughout the Java SE API and the rest of this lesson.
I'd stick to it to avo...
Python: reload component Y imported with 'from m>X m> import Y'?
In Python, once I have imported a module m>X m> in an interpreter session using import m>X m> , and the module changes on the outside, I can reload the module with reload(m>X m>) . The changes then become available in my interpreter session.
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CORS Access-Control-Allow-Headers wildcard being ignored?
...by all browsers. On browser which don't implement this yet, it must be an em>x m>act match: https://www.w3.org/TR/2014/REC-cors-20140116/#access-control-allow-headers-response-header
If you em>x m>pect a large number of headers, you can read in the value of the Access-Control-Request-Headers header and echo ...
Sorting a vector of custom objects
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A simple em>x m>ample using std::sort
struct MyStruct
{
int key;
std::string stringValue;
MyStruct(int k, const std::string& s) : key(k), stringValue(s) {}
};
struct less_than_key
{
inline bool operator() (const MyStr...