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Learning Python from Ruby; Differences and Similarities
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[x*x for x in values if x > 15]
to get a new list of the squares of all values greater than 15. In Ruby, you'd have to write the following:
values.select {|v| v > 15}.map {|v| v * v}
The Ruby code doesn't feel as compact. It's also not as efficient since it first converts the values a...
How do I check if a type is a subtype OR the type of an object?
...ass A
{
}
public class B : A
{
}
public class MyClass
{
private Type _helperType;
public Type HelperType
{
get { return _helperType; }
set
{
var testInstance = (A)Activator.CreateInstance(value);
if (testInstance==null)
t...
Do Java arrays have a maximum size?
...ry easy to test.
In a recent HotSpot VM, the correct answer is Integer.MAX_VALUE - 5. Once you go beyond that:
public class Foo {
public static void main(String[] args) {
Object[] array = new Object[Integer.MAX_VALUE - 4];
}
}
You get:
Exception in thread "main" java.lang.OutOfMemoryEr...
is_null($x) vs $x === null in PHP [duplicate]
...someone strongly suggested that I use is_null() instead as it is specifically designed for the null-evaluation purpose. He also started talking about math or something.
...
Why use a public method in an internal class?
...presents the key, documented functionality provided by this object."
Basically, my attitude is: suppose I decided to make this internal class into a public class. In order to do that, I want to change exactly one thing: the accessibility of the class. If turning an internal class into a public clas...
MySQL Orderby a number, Nulls last
... tablename WHERE visible=1 ORDER BY -position DESC, id DESC
It is essentially the inverse of position DESC placing the NULL values last but otherwise the same as position ASC.
A good reference is here http://troels.arvin.dk/db/rdbms#select-order_by
...
In Eclipse, what can cause Package Explorer “red-x” error-icon when all Java sources compile without
I'm using Eclipse for Java development. All my sources compile fine and the resulting application compiles fine. However, I keep getting an "red-x" error notification in the Package Explorer.
...
What is the purpose of double curly braces in React's JSX syntax?
... an object literal inlined in the prop value. It's the same as
var obj = {__html: rawMarkup};
<span dangerouslySetInnerHTML={obj} />
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fo...
Scatterplot with too many points
...;- data.frame(x = rnorm(5000),y=rnorm(5000))
ggplot(df,aes(x=x,y=y)) + geom_point(alpha = 0.3)
Another convenient way to deal with this is (and probably more appropriate for the number of points you have) is hexagonal binning:
ggplot(df,aes(x=x,y=y)) + stat_binhex()
And there is also regula...
How to validate a url in Python? (Malformed or not)
...
Actually, I think this is the best way.
from django.core.validators import URLValidator
from django.core.exceptions import ValidationError
val = URLValidator(verify_exists=False)
try:
val('http://www.google.com')
except Val...