大约有 30,000 项符合查询结果（耗时：0.0419秒） [XML]
Grouping functions (tapply, by, aggregate) and the *apply family
...[3,] 22 30 38 46
[4,] 24 32 40 48
If you want row/column means or sums for a 2D matrix, be sure to
investigate the highly optimized, lightning-quick colMeans,
rowMeans, colSums, rowSums.
lapply - When you want to apply a function to each element of a
list in turn and get a list bac...
NSLog the method name with Objective-C in iPhone
...-string (as of the current versions of Mac OS X and the iPhone OS) doesn't mean you should use it in that way, since Apple could change it in an OS update.
– Nick Forge
May 5 '10 at 8:06
...
What does 'low in coupling and high in cohesion' mean
...s "High cohesion is about making sure module doesn't do many things, it is meant to do only one particular thing".
– Lokesh
May 2 '17 at 9:49
...
Why does auto a=1; compile in C?
...
auto is an old C keyword that means "local scope". auto a is the same as auto int a, and because local scope is the default for a variable declared inside a function, it's also the same as int a in this example.
This keyword is actually a leftover from C...
Java enum - why use toString instead of name
...
name() is literally the textual name in the java code of the enum. That means it is limited to strings that can actually appear in your java code, but not all desirable strings are expressible in code. For example, you may need a string that begins with a number. name() will never be able to obta...
Linq to Entities - SQL “IN” clause
... 6
Using Contains, it will search for each List 1 item in List 2 that means iteration will happen 49 times !!!
share
|
improve this answer
|
follow
|
...
Parallel.ForEach() vs. foreach(IEnumerable.AsParallel())
...
What do you mean by ... Their parallel variants are used...?
– Alex Gordon
Feb 15 '17 at 7:30
2
...
Swift variable decorations with “?” (question mark) and “!” (exclamation mark)
... ?. Both are an optional, but the ! is an "implicitly unwrapped" optional, meaning that you do not have to unwrap it to access the value (but it can still be nil).
This is basically the behavior we already had in objective-c. A value can be nil, and you have to check for it, but you can also just a...
Enumerable.Empty() equivalent for IQueryable
... Unfortunately that doesn't create an actual empty IQueryable, which means it causes e.g. Union queries to be broken up into multiple queries instead of one.
– NetMage
May 22 '17 at 23:11
...
What's the difference between Protocol Buffers and Flatbuffers?
...n the PB and FB and posted this question. Thank you for the comparison! It means a lot! And I can't agree more with the benchmark section in your post the relative performance of these libraries depends deeply on the use case.
– mining
Aug 19 '14 at 0:08
...