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R object identification
...class)
sapply(obj, attributes)
attributes(obj)
names(obj)
as appropriate based on what's revealed. For example, try with:
obj <- data.frame(a=1:26, b=letters)
obj <- list(a=1:26, b=letters, c=list(d=1:26, e=letters))
data(cars)
obj <- lm(dist ~ speed, data=cars)
..etc.
If obj is an S...
What does the Java assert keyword do, and when should it be used?
...s to prove that you at least find every bug when it happens.
This idea is based on the Design-by-Contract (DbC) paradigm: you first define (with mathematical precision) what your method is supposed to do, and then verify this by testing it during actual execution. Example:
// Calculates the sum of...
Factory pattern in C#: How to ensure an object instance can only be created by a factory class?
... Any good way to require this architecture through an Interface/abstract base class? i.e. an interface/abstract base class that dictates that implementers should not expose a ctor.
– Arash Motamedi
Feb 19 '16 at 8:09
...
How can I ask the Selenium-WebDriver to wait for few seconds in Java?
...
That's import com.google.common.base.Function;, not import java.util.function.Function;
– haventchecked
Jun 22 '16 at 21:05
...
SELECT INTO using Oracle
...nto new_table
select * from old_table
/
If you want to create NEW_TABLE based on the records in OLD_TABLE ...
create table new_table as
select * from old_table
/
If the purpose is to create a new but empty table then use a WHERE clause with a condition which can never be true:
create table ...
What Haskell representation is recommended for 2D, unboxed pixel arrays with millions of pixels?
...nstance for Bool which does do bit packing, instead using a representation based on Word8. Howver, it is easy to write a bit-packing implementation for vectors -- here is one, from the (obsolete) uvector library. Under the hood, Repa uses Vectors, so I think it inherits that libraries representation...
How can I calculate an md5 checksum of a directory?
...ually everything (minus xattrs and acls), but it will sync owner and group based on their ID, not on string representation. So if you synced to a different system that doesn't necessarily have the same users/groups, you should add the --numeric-owner flag to tar
tar will include the filename of the...
Why can't I use an alias in a DELETE statement?
...
Example of a use case where this is important; deleting based on contents of a second table where there are multiple columns involved (i.e. so in or not in wouldn't work: DELETE f from dbo.foods as f where not exists (select top 1 1 from animalDiets a where a.AnimalId = f.AnimalId...
How to specify an element after which to wrap in css flexbox? [duplicate]
...to the jsfiddle. Playing around with it, I think I prefer a non-percentage-based approach, since percentage-based prevents further reflow as you shrink the container more, though you could certainly add more specific breakpoints as it shrinks (when it should go to 33%, etc).
– ...
What is a clean, pythonic way to have multiple constructors in Python?
...w__.
This could be used if the type of initialization cannot be selected based on the type of the constructor argument, and the constructors do not share code.
Example:
class MyClass(set):
def __init__(self, filename):
self._value = load_from_file(filename)
@classmethod
de...