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Remove columns from dataframe where ALL values are NA
I'm having trouble with a data frame and couldn't really resolve that issue myself:
The dataframe has arbitrary properties as columns and each row represents one data set .
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Simplest way to do a recursive self-join?
...e ultimate ancestors in your chain, change it as appropriate
UNION ALL
SELECT m.*
FROM mytable m
JOIN q
ON m.parentID = q.PersonID
)
SELECT *
FROM q
By adding the ordering condition, you can preserve the tree order:
WITH q AS
...
What are the use(s) for tags in Go?
...
A tag for a field allows you to attach meta-information to the field which can be acquired using reflection. Usually it is used to provide transformation info on how a struct field is encoded to or decoded from another format (or stored/retrie...
What does default(object); do in C#?
... value
For Nullable<T> it returns the empty (pseudo-null) value (actually, this is a re-statement of the first bullet, but it is worth making it explicit)
The biggest use of default(T) is in generics, and things like the Try... pattern:
bool TryGetValue(out T value) {
if(NoDataIsAvailab...
Print second last column/field in awk
I want to print the second last column or field in awk. The number of fields is variable. I know that I should be able to use $NF but not sure how it can be used.
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Why is it impossible to build a compiler that can determine if a C++ function will change the value
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@mrsoltys, quantum computers are "only" exponentially faster for some problems, they can not solve undecidable problems.
– zch
Jul 1 '13 at 18:52
8
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What's the difference between event.stopPropagation and event.preventDefault?
...;/div>
With stopPropagation, only the button's click handler is called while the div's click handler never fires.
Where as if you use preventDefault, only the browser's default action is stopped but the div's click handler still fires.
Below are some docs on the DOM event properties and ...
Form inside a form, is that alright? [duplicate]
...HTML5 input element's form attribute. Although we don't nest forms structurally, inputs are evaluated as they are in their own form. In my tests, 3 major browsers support this except IE(IE11). Form nesting limitation was a big obstacle for HTML UI design.
Here is a sample code, when you click Save ...
What is meant by 'first class object'?
...nction
literal) if it treats functions as
first-class objects. Specifically,
this means that the language supports
constructing new functions during the
execution of a program, storing them
in data structures, passing them as
arguments to other functions, and
returning them as the va...
Most efficient way to reverse a numpy array
Believe it or not, after profiling my current code, the repetitive operation of numpy array reversion ate a giant chunk of the running time. What I have right now is the common view-based method:
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