大约有 16,000 项符合查询结果（耗时：0.0380秒） [XML]
Why is the minimalist, example Haskell quicksort not a “true” quicksort?
Haskell's website introduces a very attractive 5-line quicksort function , as seen below.
11 Answers
...
Select n random rows from SQL Server table
...way, creating a temp table with a "random number" column, copying my table into that, looping through the temp table and updating each row with RAND() , and then selecting from that table where the random number column < 0.1. I'm looking for a simpler way to do it, in a single statement if possible...
Save classifier to disk in scikit-learn
...ier parameters is sparse (as in most text classification examples) you can convert the parameters from dense to sparse which will make a huge difference in terms of memory consumption, loading and dumping. Sparsify the model by:
clf.sparsify()
Which will automatically work for SGDClassifier but i...
Immutable vs Mutable types
...
What? Floats are immutable? But can't I do
x = 5.0
x += 7.0
print x # 12.0
Doesn't that "mut" x?
Well you agree strings are immutable right? But you can do the same thing.
s = 'foo'
s += 'bar'
print s # foobar
The value of the variable changes, but it changes by changing what the ...
What are “connecting characters” in Java identifiers?
... WAVY LOW LINE
U+FF3F ＿ FULLWIDTH LOW LINE
This compiles on Java 7.
int _, ‿, ⁀, ⁔, ︳, ︴, ﹍, ﹎, ﹏, ＿;
An example. In this case tp is the name of a column and the value for a given row.
Column<Double> ︴tp︴ = table.getColumn("tp", double.class);
double tp = row.g...
How to check edittext's text is email address or not?
...
With the introduction of new top level domains that are longer than 2-4 characters, this needs to be updated. Simply replace the {2.4}" with a "+". (e.g. joe@century21.realtor)
– Dave Owens
Ap...
What does “where T : class, new()” mean?
...
That is a constraint on the generic parameter T. It must be a class (reference type) and must have a public parameter-less default constructor.
That means T can't be an int, float, double, DateTime or any other struct (value type).
It could...
How to get Latitude and Longitude of the mobile device in android?
...ness.
LocationFinder
public class LocationFinder extends Activity {
int increment = 4;
MyLocation myLocation = new MyLocation();
// private ProgressDialog dialog;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView...
Is the ternary operator faster than an “if” condition in Java [duplicate]
...
Ternary Operator example:
int a = (i == 0) ? 10 : 5;
You can't do assignment with if/else like this:
// invalid:
int a = if (i == 0) 10; else 5;
This is a good reason to use the ternary operator. If you don't have an assignment:
(i == 0) ? foo ...
Difference between signed / unsigned char [duplicate]
So I know that the difference between a signed int and unsigned int is that a bit is used to signify if the number if positive or negative, but how does this apply to a char ? How can a character be positive or negative?
...