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difference between foldLeft and reduceLeft in Scala
...e between reducing and folding
The difference is not the implementation at all, just look at the signatures.
The question doesn't have anything to do with Scala in particular, it's rather about the two concepts of functional programming.
Back to your question:
Here is the signature of foldLeft (c...
Only read selected columns
...g","Sep","Oct","Nov","Dec"))
dat <- fread("data.txt", drop = c(8:13))
All result in:
> data
Year Jan Feb Mar Apr May Jun
1 2009 -41 -27 -25 -31 -31 -39
2 2010 -41 -27 -25 -31 -31 -39
3 2011 -21 -27 -2 -6 -10 -32
UPDATE: When you don't want fread to return a data.table, use the data.ta...
How can I use pointers in Java?
...
All objects in Java are references and you can use them like pointers.
abstract class Animal
{...
}
class Lion extends Animal
{...
}
class Tiger extends Animal
{
public Tiger() {...}
public void growl(){...}
}
Tiger fi...
Is there a performance difference between i++ and ++i in C++?
...
However, if i is an instance of a C++ class, then i++ and ++i are making calls to one of the operator++ functions. Here's a standard pair of these functions:
Foo& Foo::operator++() // called for ++i
{
this->data += 1;
return *this;
}
Foo Foo::operator++(int ignored_dummy_value) ...
What are the differences between .so and .dylib on osx?
...xecutables and libraries distinguishes between shared libraries and dynamically loaded modules. Use otool -hv some_file to see the filetype of some_file.
Mach-O shared libraries have the file type MH_DYLIB and carry the extension .dylib. They can be linked against with the usual static linker flags...
Vim: apply settings on files in directory
How do I specify Vim settings for all files under the current directory?
11 Answers
11...
WKWebView not loading local files under iOS 8
...
They finally solved the bug! Now we can use -[WKWebView loadFileURL:allowingReadAccessToURL:].
Apparently the fix was worth some seconds in WWDC 2015 video 504 Introducing Safari View Controller
For iOS8 ~ iOS10 (Swift 3)
As Da...
OceanBase使用libeasy原理源码分析：服务器端 - 数据库(内核) - 清泛网 - ...
...nection_t(TCP连接)的输出缓冲区链表中
handler_.encode = ObMySQLCallback::encode;
// libeasy回调这个函数用于从该连接的输入缓冲区中反序列化出一个符合MySQL协议的包，然后吐给上层使用
handler_.decode = ObMySQLCallback::decode;
// 对于每个decode...
How to manually set an authenticated user in Spring Security / SpringMVC
After a new user submits a 'New account' form, I want to manually log that user in so they don't have to login on the subsequent page.
...
In Django - Model Inheritance - Does it allow you to override a parent model's attribute?
...ld instances (at least,
not at the moment). If a base class has a field called author, you
cannot create another model field called author in any class that
inherits from that base class.
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