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How to take the first N items from a generator or list in Python? [duplicate]
...imple syntax: array[start:stop:step]
You can omit any parameter. These are all valid: array[start:], array[:stop], array[::step]
Slicing a generator
import itertools
top5 = itertools.islice(my_list, 5) # grab the first five elements
You can't slice a generator directly in Python. itertools.i...
How does C compute sin() and other math functions?
...on in C, contributed by IBM. Since October 2011, this is the code that actually runs when you call sin() on a typical x86-64 Linux system. It is apparently faster than the fsin assembly instruction. Source code: sysdeps/ieee754/dbl-64/s_sin.c, look for __sin (double x).
This code is very complex. N...
Scala: Abstract types vs generics
... Sommers (May 18, 2009)
Update (October2009): what follows below has actually been illustrated in this new article by Bill Venners:
Abstract Type Members versus Generic Type Parameters in Scala (see summary at the end)
(Here is the relevant extract of the first interview, May 2009, emphasis min...
How to use WPF Background Worker
...
private void worker_DoWork(object sender, DoWorkEventArgs e)
{
// run all background tasks here
}
private void worker_RunWorkerCompleted(object sender,
RunWorkerCompletedEventArgs e)
{
//update ui once worker complete his work
}
Run worker async...
Max length UITextField
... that can be entered into a UITextField using swift? , I saw that if I use all 10 characters, I can't erase the character too.
...
How to print struct variables in console?
... @fnr If you have a JSON document, you would need to unmarshall it, before being able to print its field.
– VonC
Jul 1 '14 at 14:16
...
Why are Subjects not recommended in .NET Reactive Extensions?
...
Ok,
If we ignore my dogmatic ways and ignore "subjects are good/bad" all together. Let us look at the problem space.
I bet you either have 1 of 2 styles of system you need to ingrate to.
The system raises an event or a call back when a message arrives
You need to poll the system to see if t...
常用Sql - 数据库(内核) - 清泛网 - 专注C/C++及内核技术
...,0) NOT NULL COMMENT '递增ID',
`FIELD_1` varchar(32) NOT NULL COMMENT '字段1',
`FIELD_2` varchar(32) NOT NULL COMMENT '字段2',
PRIMARY KEY (`ID`),
KEY `FIELD_1` (`FIELD_1`), #单索引
KEY `FIELD_1_2` (`FIELD_1`, `F...
Can C++ code be valid in both C++03 and C++11 but do different things?
... // #1
void f(...); // #2
template<int N> void g() {
f(0*N); // Calls #2; used to call #1
}
Rounded results after integer division and modulo
In C++03 the compiler was allowed to either round towards 0 or towards negative infinity. In C++11 it is mandatory to round towards 0
int i = (-1) ...
Scala how can I count the number of occurrences in a list
...", "banana", "apple", "oranges", "oranges")
s.groupBy(identity).mapValues(_.size)
giving a Map with a count for each item in the original sequence:
Map(banana -> 1, oranges -> 3, apple -> 3)
The question asks how to find the count of a specific item. With this approach, the solution w...