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Why does X[Y] join of data.tables not allow a full outer join, or a left join?
...Y) does both ways at the same time. The number of rows of X[Y] and Y[X] usually differ, whereas the number of rows returned by merge(X,Y) and merge(Y,X) is the same.
BUT that misses the main point. Most tasks require something to be done on the
data after a join or merge. Why merge all the co...
JSON serialization of Google App Engine models
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There is a small mistake in the code: Where you have "output[key] = to_dict(model)" it should be: "output[key] = to_dict(value)". Besides that it's perfect. Thanks!
– arikfr
Nov 7 '09 at 22:02
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Export and Import all MySQL databases at one time
I want to keep a backup of all my MySQL databases. I have more than 100 MySQL databases. I want to export all of them at the same time and again import all of them into my MySQL server at one time. How can I do that?
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How to generate all permutations of a list?
How do you generate all the permutations of a list in Python, independently of the type of elements in that list?
33 Answer...
iPhone Simulator suddenly started running very slow
...lator for a number of weeks and it has been running well up until now, but all of a sudden has begun running very slow both when loading content and animations. I have not made any changes to my code since I last tested it successfully.
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Difference between this and self in self-type annotations?
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All three forms are valid, and have the effect that B is assumed as the type of this in class A.
The first two variants
trait A { self: B => ... }
trait A { foo: B => ... }
introduce self (respectively, foo) as an ...
Why do some claim that Java's implementation of generics is bad?
I've occasionally heard that with generics, Java didn't get it right. (nearest reference, here )
13 Answers
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Update statement with inner join on Oracle
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The second example has the benefit of allowing you to test the SQL before actually performing the update.
– Daniel Reis
Jan 19 '12 at 10:18
11
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How to add item to the beginning of List?
...ssible to insert at the end of the list?
– Gary Henshall
Dec 11 '17 at 14:36
3
@GaryHenshall yes,...
Can one do a for each loop in java in reverse order?
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The Collections.reverse method actually returns a new list with the elements of the original list copied into it in reverse order, so this has O(n) performance with regards to the size of the original list.
As a more efficient solution, you could write a deco...