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Slicing of a NumPy 2d array, or how do I extract an mxm submatrix from an nxn array (n>m)?
...every other column, then you can do it with basic slicing:
In [49]: x=np.arange(16).reshape((4,4))
In [50]: x[1:4:2,1:4:2]
Out[50]:
array([[ 5, 7],
[13, 15]])
This returns a view, not a copy of your array.
In [51]: y=x[1:4:2,1:4:2]
In [52]: y[0,0]=100
In [53]: x # <---- Notice x[...
What are the undocumented features and limitations of the Windows FINDSTR command?
... only way to match <CR> or <LF> is via a regex character class range expression that sandwiches the EOL characters.
[<TAB>-<0x0B>] matches <LF>, but it also matches <TAB> and <0x0B>
[<0x0C>-!] matches <CR>, but it also matches <0x0C> and ...
How to avoid mysql 'Deadlock found when trying to get lock; try restarting transaction'
...ing it up like this is less efficient but it avoids the need to hold a key-range lock during the delete.
Also, modify your select queries to add a where clause excluding rows older than 900 seconds. This avoids the dependency on the cron job and allows you to reschedule it to run less often.
Th...
How to check which version of v8 is installed with my NodeJS?
...*//'`; V=`echo $V | sed -e 's/ /\./g'`; URL=https://github.com/joyent/node/raw/v$V/ChangeLog; curl --silent $URL | grep 'Upgrade v8' | head -1 | sed -e 's/^.* //'; unset V; unset URL
For example, in my box with node.js 0.4.7 I get:
3.1.8.10
:)
...
What is the difference between the dot (.) operator and -> in C++? [duplicate]
...
Note that this is only for raw pointers. For class types that overload the operator, it has some other interesting properties...
– David Rodríguez - dribeas
Jul 17 '12 at 18:19
...
Generator Expressions vs. List Comprehension
...tended with lists, and generators are not quite iterables. a = (x for x in range(0,10)), b = [1,2,3] for instance. a.extend(b) throws an exception. b.extend(a) will evaluate all of a, in which case there's no point in making it a generator in the first place.
– Slater Victoroff...
How can I add reflection to a C++ application?
...ow to iterate over the fields we use the visitor pattern. We create an MPL range from 0 to the number of fields, and access the field data at that index. Then it passes the field data on to the user-provided visitor:
struct field_visitor
{
template<class C, class Visitor, class I>
voi...
Take the content of a list and append it to another list
...instead of
list2.append(list1)
Here's the difference:
>>> a = range(5)
>>> b = range(3)
>>> c = range(2)
>>> b.append(a)
>>> b
[0, 1, 2, [0, 1, 2, 3, 4]]
>>> c.extend(a)
>>> c
[0, 1, 0, 1, 2, 3, 4]
Since list.extend() accepts an ar...
How to know what the 'errno' means?
...roken pipe
33 EDOM Numerical argument out of domain
34 ERANGE Numerical result out of range
35 EDEADLK Resource deadlock avoided
35 EDEADLOCK Resource deadlock avoided
36 ENAMETOOLONG File name too long
37 ENOLCK No locks av...
How to sum up elements of a C++ vector?
...gin(), vector.end(), [&] (int n) {
sum_of_elems += n;
});
Using a range-based for loop (thanks to Roger Pate):
for (auto& n : vector)
sum_of_elems += n;
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