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insert vs emplace vs operator[] in c++ map
I'm using maps for the first time and I realized that there are many ways to insert an element. You can use emplace() , operator[] or insert() , plus variants like using value_type or make_pair . While there is a lot of information about all of them and questions about particular cases, I sti...
Encoding Javascript Object to Json string
I want to encode a Javascript object into a JSON string and I am having considerable difficulties.
2 Answers
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Define all functions in one .R file, call them from another .R file. How, if possible?
...If abc.R is:
fooABC <- function(x) {
k <- x+1
return(k)
}
and xyz.R is:
fooXYZ <- function(x) {
k <- fooABC(x)+1
return(k)
}
then this will work:
> source("abc.R")
> source("xyz.R")
> fooXYZ(3)
[1] 5
>
Even if there are cyclical dependencies, this wi...
Hibernate: hbm2ddl.auto=update in production?
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Also updating a db schema should be handled by the professionals ( dbas ). Recovering from a bad db change is difficult at best. Vova didn't mention it - but what happens if hibernate's update decides to drop a column and re-add it because the type or size chan...
Return first N key:value pairs from dict
...is answer is no longer correct. Python dicts now preserve insertion order, and this is explicitly documented.
– Konrad Rudolph
Sep 22 at 12:30
1
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Installing R with Homebrew
I'm trying to install R using Homebrew. I ran these commands which are recommended elsewhere on SO:
12 Answers
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Why does substring slicing with index out of range work?
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You're correct! 'example'[3:4] and 'example'[3] are fundamentally different, and slicing outside the bounds of a sequence (at least for built-ins) doesn't cause an error.
It might be surprising at first, but it makes sense when you think about it. Indexi...
How to remove k__BackingField from json when Deserialize
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Lol,implemented the long version and it set the private fields to the client.home: Object _fName: "Storefront" _headline: "CEO at StorefrontDoors.NET" _id: "" _industry: ""
– Filling The Stack is What I DO
Oct 23 '12 at...
Finding quaternion representing the rotation from one vector to another
I have two vectors u and v. Is there a way of finding a quaternion representing the rotation from u to v?
7 Answers
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Extract subset of key-value pairs from Python dictionary object?
...bigdict.get(k, None) for k in ('l', 'm', 'n')}
If you're using Python 3, and you only want keys in the new dict that actually exist in the original one, you can use the fact to view objects implement some set operations:
{k: bigdict[k] for k in bigdict.keys() & {'l', 'm', 'n'}}
...