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dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...e to go with @Moody_Mudskipper's answer: Using .drop=FALSE can give potentially unexpected results when one or more grouping variables are not coded as factors. See examples below:
library(dplyr)
data(iris)
# Add an additional level to Species
iris$Species = factor(iris$Species, levels=c(levels(ir...
How to define servlet filter order of execution using annotations in WAR
...ation. However, to minimize the web.xml usage, it's sufficient to annotate all filters with just a filterName so that you don't need the <filter> definition, but just a <filter-mapping> definition in the desired order.
For example,
@WebFilter(filterName="filter1")
public class Filter1 ...
isset() and empty() - what to use
... check - is variable empty or contains something. To solve this task, I usually do the following.
6 Answers
...
Delete all rows in an HTML table
How can I delete all rows of an HTML table except the <th> 's using Javascript, and without looping through all the rows in the table? I have a very huge table and I don't want to freeze the UI while I'm looping through the rows to delete them
...
Redirect from an HTML page
...=http://example.com/" />
Note: Place it in the head section.
Additionally for older browsers if you add a quick link in case it doesn't refresh correctly:
<p><a href="http://example.com/">Redirect</a></p>
Will appear as
Redirect
This will still allow you to get to ...
How do I configure Maven for offline development?
...ection to the internet at some point to be able to use it? Meaning specifically getting the internal maven plugins for compiling, cleaning, packaging, etc?
...
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
...
How can I select every other line with multiple cursors in Sublime Text?
...t already enabled, enable them: Alt+R
Type in the expression .*\n.*\n
Find all: Alt+Enter
Press left arrow to get rid of the selections, leaving just the cursors: ←
You now have a cursor at the start of every odd-numbered line. If you wanted even-numbered lines, press down: ↓
Depending on the fi...
How to format numbers by prepending 0 to single-digit numbers?
... @Joseph .75 is transformed in 75.
– Galled
Nov 25 '11 at 22:06
@Galled normally that kind of thing is ...
How do I get a consistent byte representation of strings in C# without manually specifying an encodi
How do I convert a string to a byte[] in .NET (C#) without manually specifying a specific encoding?
40 Answers
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