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dplyr: “Error in n(): function should not be called directly”
...ction" specification, like example below:
delay <- dplyr::summarise(by_tailnum,
count = n(),
dist = mean(distance, na.rm = TRUE),
delay = mean(arr_delay, na.rm = TRUE))
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Tomcat: How to find out running tomcat version
....in/blog/check-jsp-tomcat-version
Save this code into a file called tomcat_version.jsp:
Tomcat Version : <%= application.getServerInfo() %><br>
Servlet Specification Version :
<%= application.getMajorVersion() %>.<%= application.getMinorVersion() %> <br> ...
How to close tag properly?
...es the tag properly. Best to add the alt attribute for people that are visually impaired.
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linq where list contains any in list
...
Sounds like you want:
var movies = _db.Movies.Where(p => p.Genres.Intersect(listOfGenres).Any());
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fo...
Why is Java Vector (and Stack) class considered obsolete or deprecated?
... each individual operation. That's almost never what you want to do.
Generally you want to synchronize a whole sequence of operations. Synchronizing individual operations is both less safe (if you iterate over a Vector, for instance, you still need to take out a lock to avoid anyone else changing t...
C# code to validate email address
...e-mail addresses are more forgiving than you might first assume. These are all perfectly valid forms:
cog@wheel
"cogwheel the orange"@example.com
123@$.xyz
For most use cases, a false "invalid" is much worse for your users and future proofing than a false "valid". Here's an article that used to ...
delegate keyword vs. lambda notation
... If you specify an anonymous method without specifying a parameter list at all it is compatible with any delegate type returning void and without any out parameters. Armed with this knowledge, we should be able to construct two overloads to make the expressions completely unambiguous but very differ...
Maximum number of records in a MySQL database table
... The poster is not asking about numeric or any other data types. . I really do not understand how this can be flagged as a correct answer. Though I must admit that the question is ambiguous we should distinguish between PK data type and maximum number of rows for a table.
–...
How to change a table name using an SQL query?
...
Use sp_rename:
EXEC sp_rename 'Stu_Table', 'Stu_Table_10'
You can find documentation on this procedure on MSDN.
If you need to include a schema name, this can only be included in the first parameter (that is, this cannot be use...
Finding the type of an object in C++
...
dynamic_cast should do the trick
TYPE& dynamic_cast<TYPE&> (object);
TYPE* dynamic_cast<TYPE*> (object);
The dynamic_cast keyword casts a datum from one pointer or reference type to another, performing a runtime...