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dplyr summarise: Equivalent of “.drop=FALSE” to keep groups with zero length in output
...pecially since your data are already factored, you can use complete from "tidyr" to get what you might be looking for:
library(tidyr)
df %>%
group_by(b) %>%
summarise(count_a=length(a)) %>%
complete(b)
# Source: local data frame [3 x 2]
#
# b count_a
# (fctr) (int)
# 1 ...
Python - write() versus writelines() and concatenated strings
...e a string for a newline in write() but I can use it in writelines()?
The idea is the following: if you want to write a single string you can do this with write(). If you have a sequence of strings you can write them all using writelines().
write(arg) expects a string as argument and writes it to ...
How can I make my own event in C#?
... will contain information about the triggered event.
public delegate void MyEventHandler(object source, MyEventArgs e);
//This is a class which describes the event to the class that recieves it.
//An EventArgs class must always derive from System.EventArgs.
public class MyEventArgs ...
Difference between Pragma and Cache-Control headers?
...ure, you must first check with me that it is up-to-date (i.e. perform revalidation)".
– clime
Mar 7 '13 at 14:03
...
What's the longest possible worldwide phone number I should consider in SQL varchar(length) for phon
What's the longest possible worldwide phone number I should consider in SQL varchar(length) for phone.
5 Answers
...
How to cancel a Task in await?
...y unchanged since then) and the Task-Based Asynchronous Pattern, which provides guidelines on how to use CancellationToken with async methods.
To summarize, you pass a CancellationToken into each method that supports cancellation, and that method must check it periodically.
private async Task TryT...
Why doesn't the JVM cache JIT compiled code?
... Because it's probably not worth it. If neither SUN, IBM nor BEA considered it worthwhile for their performance JVMs, there's going to be a good reason for it. Maybe their RT optimisation is faster than Oracle's, which is why Oracle caches it.
– skaffman
...
When to use Task.Delay, when to use Thread.Sleep?
... Both operations are quite heavy whereas the cooperative multi-tasking provided by Task.Delay etc is designed to avoid all of that overhead, maximize throughput, allow cancellation, and provide cleaner code.
– Corillian
May 3 '16 at 16:06
...
Running a command as Administrator using PowerShell?
...
if (-NOT ([Security.Principal.WindowsPrincipal][Security.Principal.WindowsIdentity]::GetCurrent()).IsInRole([Security.Principal.WindowsBuiltInRole] "Administrator"))
{
$arguments = "& '" +$myinvocation.mycommand.definition + "'"
Start-Process powershell -Verb runAs -ArgumentList $argume...
Why XML-Serializable class need a parameterless constructor
...tialize it during deserialization.
Since you are using xml, you might consider using DataContractSerializer and marking your class with [DataContract]/[DataMember], but note that this changes the schema (for example, there is no equivalent of [XmlAttribute] - everything becomes elements).
Update: ...