大约有 16,000 项符合查询结果（耗时：0.0214秒） [XML]
Convert data.frame columns from factors to characters
... data.frame(lapply(bob, as.character), stringsAsFactors=FALSE)
This will convert all variables to class "character", if you want to only convert factors, see Marek's solution below.
As @hadley points out, the following is more concise.
bob[] <- lapply(bob, as.character)
In both cases, lapp...
How to return only the Date from a SQL Server DateTime datatype
...
On SQL Server 2008 and higher, you should CONVERT to date:
SELECT CONVERT(date, getdate())
On older versions, you can do the following:
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, @your_date))
for example
SELECT DATEADD(dd, 0, DATEDIFF(dd, 0, GETDATE()))
gives me ...
How to read values from properties file?
... How do we use aaa? Is it @Value(${aaa}) private String aaa; then we can System.out.println(aaa)???????
– user1685185
Feb 13 '14 at 5:19
2
...
Why is “while ( !feof (file) )” always wrong?
...he result we must use is the return value of scanf, the number of elements converted.
C++, iostreams formatted extraction:
for (int n; std::cin >> n; ) {
consume(n);
}
The result we must use is std::cin itself, which can be evaluated in a boolean context and tells us whether the ...
Java's Virtual Machine and CLR
...in run-time environments: bytecode compilation and dynamic compilation. It converts code at runtime prior to executing it natively, for example bytecode into native machine code. The performance improvement over interpreters originates from caching the results of translating blocks of code, and not ...
How to convert an array to object in PHP?
How can i convert an array like this to object?
34 Answers
34
...
Clear variable in python
...ed (import os) are going to remain imported because they are referenced by sys.modules; subsequent imports will reuse the already imported module object. You just won't have a reference to them in your current global namespace.
Please reconsider this answer!
...
Java - Method name collision in interface implementation
...son (usually optimization is the only valid reason) you want to be able to convert it to Beta, you could make a sub-interface of Alfa with Beta asBeta() in it.
share
|
improve this answer
|...
Get program execution time in the shell
...cute PIPELINE and print a summary of the real time, user CPU time,
and system CPU time spent executing PIPELINE when it terminates.
The return status is the return status of PIPELINE. The `-p' option
prints the timing summary in a slightly different format. This uses
the value of t...
How do I invert BooleanToVisibilityConverter?
I'm using a BooleanToVisibilityConverter in WPF to bind the Visibility property of a control to a Boolean . This works fine, but I'd like one of the controls to hide if the boolean is true , and show if it's false .
...