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What is move semantics?
...ng
{
char* data;
public:
string(const char* p)
{
size_t size = std::strlen(p) + 1;
data = new char[size];
std::memcpy(data, p, size);
}
Since we chose to manage the memory ourselves, we need to follow the rule of three. I am going to defer writing the assi...
How do I prevent site scraping? [closed]
...ing here, using that. A real browser will never use only that)
"Java 1.7.43_u43" (By default, Java's HttpUrlConnection uses something like this.)
"BIZCO EasyScraping Studio 2.0"
"wget", "curl", "libcurl",.. (Wget and cURL are sometimes used for basic scraping)
If you find that a specific User Agen...
Select first 4 rows of a data.frame in R
...
156
Use head:
dnow <- data.frame(x=rnorm(100), y=runif(100))
head(dnow,4) ## default is 6
...
Pandas index column title or name
... JeffJeff
100k1717 gold badges187187 silver badges162162 bronze badges
10
...
Regular expression that matches valid IPv6 addresses
I'm having trouble writing a regular expression that matches valid IPv6 addresses, including those in their compressed form (with :: or leading zeros omitted from each byte pair).
...
Ineligible Devices section appeared in Xcode 6.x.x
After installing Xcode 6 my devices moved to greyed-out section Ineligible Devices and I can't select them as deploy target:
...
All combinations of a list of lists
...ols.product:
>>> import itertools
>>> a = [[1,2,3],[4,5,6],[7,8,9,10]]
>>> list(itertools.product(*a))
[(1, 4, 7), (1, 4, 8), (1, 4, 9), (1, 4, 10), (1, 5, 7), (1, 5, 8), (1, 5, 9), (1, 5, 10), (1, 6, 7), (1, 6, 8), (1, 6, 9), (1, 6, 10), (2, 4, 7), (2, 4, 8), (2, 4, 9), ...
pandas: filter rows of DataFrame with operator chaining
..." filtering is done by "chaining" the criteria in the boolean index.
In [96]: df
Out[96]:
A B C D
a 1 4 9 1
b 4 5 0 2
c 5 5 1 0
d 1 3 9 6
In [99]: df[(df.A == 1) & (df.D == 6)]
Out[99]:
A B C D
d 1 3 9 6
If you want to chain methods, you can add your own mask ...
What is the syntax to insert one list into another list in python?
...
6 Answers
6
Active
...
Transpose list of lists
...
How about
map(list, zip(*l))
--> [[1, 4, 7], [2, 5, 8], [3, 6, 9]]
For python 3.x users can use
list(map(list, zip(*l)))
Explanation:
There are two things we need to know to understand what's going on:
The signature of zip: zip(*iterables) This means zip expects an arbitrary n...