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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 ...
Why not use exceptions as regular flow of control?
To avoid all standard-answers I could have Googled on, I will provide an example you all can attack at will.
24 Answers
...
Boolean operators && and ||
...ing). For example, here's a comparison using an undefined value a; if it didn't short-circuit, as & and | don't, it would give an error.
a
# Error: object 'a' not found
TRUE || a
# [1] TRUE
FALSE && a
# [1] FALSE
TRUE | a
# Error: object 'a' not found
FALSE & a
# Error: object 'a' ...
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
...
Is it bad practice to have a constructor function return a Promise?
...uctor for a blogging platform and it has many async operations going on inside. These range from grabbing the posts from directories, parsing them, sending them through template engines, etc.
...
Do you have to put Task.Run in a method to make it async?
...essions). async methods may return Task, Task<T>, or (if you must) void.
Any type that follows a certain pattern can be awaitable. The most common awaitable types are Task and Task<T>.
So, if we reformulate your question to "how can I run an operation on a background thread in a way th...
Difference between Grunt, NPM and Bower ( package.json vs bower.json )
...s :).
I do have a bit of experience with rails, so I'm familiar with the idea of files for listing dependencies (such as bundler Gemfile)
...
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: ...
What is the recommended approach towards multi-tenant databases in MongoDB?
...
I have the same problem to solve and also considering variants.
As I have years of experience creating SaaS multi-tenant applicatios I also was going to select the second option based on my previous experience with the relational databases.
While making my research I f...
What is the lifetime of a static variable in a C++ function?
...emitter() { cout << "Destroyed " << str << endl; }
};
void foo(bool skip_first)
{
if (!skip_first)
static emitter a("in if");
static emitter b("in foo");
}
int main(int argc, char*[])
{
foo(argc != 2);
if (argc == 3)
foo(false);
}
Output:
C:>...