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Why were pandas merges in python faster than data.table merges in R in 2012?
...re-computed indexes for various columns to accelerate operations like data selection and merges. In this case (database joins) pandas' DataFrame contains no pre-computed information that is being used for the merge, so to speak it's a "cold" merge. If I had stored the factorized versions of the join...
“Keep Me Logged In” - the best approach
...lution
A better solution would be
User is logged in and remember me is selected
Generate Token & signature and store in cookie
The tokens are random and are only valid for single autentication
The token are replace on each visit to the site
When a non-logged user visit the site the signa...
How to prove that a problem is NP complete?
...o NP (that is that given a solution you can verify it in polynomial time)
Select a known NP-complete problem L'
Describe an algorithm f that transforms L' into L
Prove that your algorithm is correct (formally: x ∈ L' if and only if f(x) ∈ L )
Prove that algo f runs in polynomial time
...
How to implement Rate It feature in Android App
...lay the pop up for 3 days and 10 launches. The same is done for those that selected to rate it, however the delays is longer (not to bother the user so soon in case that he has actually rated the app. This can be changed to not be shown again, then you will have to alter the code to your like). Hope...
LINQ to Entities only supports casting EDM primitive or enumeration types with IEntity interface
...i eventually found the solution which was for my extension method to call .Select(e => e as T) where T is the child class and e is the base class.
full details are here:
Create IQueryable<T> extension using base class in EF
...
Django dynamic model fields
...y constraint, which may be inefficient on some databases.
You will need to select one of the forks, since the official package is no longer maintained and there is no clear leader.
The usage is pretty straightforward:
import eav
from app.models import Patient, Encounter
eav.register(Encounter)
e...
The quest for the Excel custom function tooltip
...{
return v1 + v2;
}
we get both the function description
and when selecting the function, we get argument help
That looks nice, but it's all still very flaky, only works on my machine and sometimes crashes Excel. It might be a start, though...
Update 9 May 2014:
I've made some progre...
Bootstrap combining rows (rowspan)
... a row doesn't have to use row-fluid to accomplish this as suggested by my selected answer. I really appreciate it though!
– Seong Lee
May 3 '13 at 5:36
...
Many-to-many relationship with the same model in rails?
...ails generates in the log file. You'll find something like the following:
SELECT * FROM "posts"
INNER JOIN "post_connections" ON "posts".id = "post_connections".post_b_id
WHERE ("post_connections".post_a_id = 1 )
To make the association bi-directional, we'd have to find a way to make Rails OR the...
Print only?
...I was able to solve this by using some additional display:none styling for selected items but perhaps a more general solution is achievable by some combination of also forcing heights, overflow:none and absolute positioning for all divs or something.
– Malcolm MacLeod
...