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How to Correctly Use Lists in R?
...st?) contemporary programming languages in widespread use have at least a handful of ADTs [abstract data types] in common, in particular,
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How to generate all permutations of a list?
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Starting with Python 2.6 (and if you're on Python 3) you have a standard-library tool for this: itertools.permutations.
import itertools
list(itertools.permutations([1, 2, 3]))
If you're using an older Python (<2.6) for some reason or are just...
biggest integer that can be stored in a double
...more do you want?
Go on, ask me what the largest integer is, such that it and all smaller integers can be stored in IEEE 64-bit doubles without losing precision. An IEEE 64-bit double has 52 bits of mantissa, so I think it's 253:
253 + 1 cannot be stored, because the 1 at the start and the 1 at t...
conditional unique constraint
...onstraint like this. The difference is, you'll return false if Status = 1 and Count > 0.
http://msdn.microsoft.com/en-us/library/ms188258.aspx
CREATE TABLE CheckConstraint
(
Id TINYINT,
Name VARCHAR(50),
RecordStatus TINYINT
)
GO
CREATE FUNCTION CheckActiveCount(
@Id INT
) RETURNS INT...
How to access the last value in a vector?
... vector that is nested in a dataframe one or two levels. Is there a quick and dirty way to access the last value, without using the length() function? Something ala PERL's $# special var?
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When should I use Struct vs. OpenStruct?
In general, what are the advantages and disadvantages of using an OpenStruct as compared to a Struct? What type of general use-cases would fit each of these?
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ReactJS: Modeling Bi-Directional Infinite Scrolling
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This is a mix of an infinite table and an infinite scroll scenario. The best abstraction I found for this is the following:
Overview
Make a <List> component that takes an array of all children. Since we do not render them, it's really cheap to just all...
Does return stop a loop?
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Yes, return stops execution and exits the function. return always** exits its function immediately, with no further execution if it's inside a for loop.
It is easily verified for yourself:
function returnMe() {
for (var i = 0; i < 2; i++) {
...
Is there a builtin identity function in python?
...ng some more research, there is none, a feature was asked in issue 1673203 And from Raymond Hettinger said there won't be:
Better to let people write their own trivial pass-throughs
and think about the signature and time costs.
So a better way to do it is actually (a lambda avoids naming the...
how to show lines in common (reverse diff)?
...ines in common rather than the lines which are different between them. Command line unix or windows is fine.
7 Answers
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