大约有 40,000 项符合查询结果（耗时：0.0683秒） [XML]
What's the fastest way to merge/join data.frames in R?
...(y) from main.d group by g1, g2"))
)
The outputs from the two benchmark call comparing the merge calculations are:
Joining by: x
test replications elapsed relative user.self sys.self user.child sys.child
3 data.table 1 0.34 1.000000 0.31 0.01 NA NA
2 ...
Disable individual Python unit tests temporarily
... so. You could just get this module and use it on your existing Python install. It will probably work.
Before this, I used to rename the tests I wanted skipped to xtest_testname from test_testname.
Here's a quick elisp script to do this. My elisp is a little rusty so I apologise in advance for ...
select count(*) from table of mysql in php
... to alias the aggregate using the as keyword in order to call it from mysql_fetch_assoc
$result=mysql_query("SELECT count(*) as total from Students");
$data=mysql_fetch_assoc($result);
echo $data['total'];
share
|...
How to implement an abstract class in ruby?
I know there is no concept of abstract class in ruby. But if at all it needs to be implemented, how to go about it? I tried something like...
...
Correct Bash and shell script variable capitalization
I run across many shell scripts with variables in all caps, and I've always thought that there is a severe misunderstanding with that. My understanding is that, by convention (and perhaps by necessity long ago), environment variables are in all-caps.
...
Proper Linq where clauses
...collection where as in the first one, it's applying the first predicate to all items first and the result (which is narrowed down at this point) is used for the second predicate and so on. The results get narrowed down every pass but still it involves multiple passes.
Also the chaining (first metho...
How do I dump an object's fields to the console?
...
Adding an inspect method to your class allows you to define how the class' attributes are displayed, rather than rely on default output. A lot of classes don't implement it well, but it can be really useful when debugging. Ruby will fall back to to_s if it can't f...
Number of elements in a javascript object
...
Although JS implementations might keep track of such a value internally, there's no standard way to get it.
In the past, Mozilla's Javascript variant exposed the non-standard __count__, but it has been removed with version 1.8.5.
For cross-browser scripting you're stuck with explicitly ite...
Guava equivalent for IOUtils.toString(InputStream)
...ou.
This is exactly what Jon Skeet suggested, except that there isn't actually any overload of CharStreams.newReaderSupplier that takes an InputStream as input... you have to give it an InputSupplier:
InputSupplier<? extends InputStream> supplier = ...
InputSupplier<InputStreamReader> ...
How to delete all Annotations on a MKMapView
Is there a simple way to delete all the annotations on a map without iterating through all the displayed annotations in Objective-c?
...