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How can I reverse the order of lines in a file?
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There's the well-known sed tricks:
# reverse order of lines (emulates "tac")
# bug/feature in HHsed v1.5 causes blank lines to be deleted
sed '1!G;h;$!d' # method 1
sed -n '1!G;h;$p' # method 2
(Explanation: prepen...
Create an index on a huge MySQL production table without table locking
...ating MySQL's Schema without downtime
Thusfar, there's only one method I know of to update a MySql schema and not suffer an availability outage. Circular masters:
Master A has your MySQL database running on it
Bring Master B into service and have it replicate writes from Master A ( B is a slave ...
prototype based vs. class based inheritance
...psulation of data along with associated operations on the data, variously known as data members and member functions, or as data and methods, among other things.
inheritance, the ability to say that these objects are just like that other set of objects EXCEPT for these changes
polymorphism ("many sh...
How do you bind an Enum to a DropDownList control in ASP.NET?
... Why does this have so many upvotes. The code (at least c#) does now work and contains syntax errors.
– Dave
Oct 3 '16 at 21:53
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How to calculate the angle between a line and the horizontal axis?
...aX*deltaX+deltaY*deltaY)), unless the length is 0.
After that, deltaX will now be the cosine of the angle between the vector and the horizontal axis (in the direction from the positive X to the positive Y axis at P1).
And deltaY will now be the sine of that angle.
If the vector's length is 0, it won...
Share Large, Read-Only Numpy Array Between Multiprocessing Processes
...ing a multiprocessing.RawArray() and mapping NumPy dtype s to ctype s. Now, numpy-sharedmem seems to be the way to go, but I've yet to see a good reference example. I don't need any kind of locks, since the array (actually a matrix) will be read-only. Now, due to its size, I'd like to avoid a ...
Which ORM should I use for Node.js and MySQL? [closed]
...e. I started using Sequelize recently and was quite pleased by the docs. Now it's an auto-generated pile of broken links, outdated information, and incomplete examples. I'll still stick with it though. It isn't that hard to learn.
– Brad
Jan 14 '15 at 2:49
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Can anyone explain python's relative imports?
...nit__.py
./pkg/sub/relative.py
With start.py:
import pkg.sub.relative
Now pkg is the top level package and your relative import should work.
If you want to stick with your current layout you can just use import parent. Because you use start.py to launch your interpreter, the directory where ...
How can I conditionally require form inputs with AngularJS?
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This feature is documented by now: docs.angularjs.org/api/ng/directive/ngRequired
– bjunix
May 9 '16 at 11:42
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Are there any O(1/n) algorithms?
...ensible when we take the mathematical definition of the Big O notation:
Now you can easily substitute g(x) for 1/x … it's obvious that the above definition still holds for some f.
For the purpose of estimating asymptotic run-time growth, this is less viable … a meaningful algorithm cannot ge...