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Applying a function to every row of a table using dplyr?
...a good handle on this topic.
The most straightforward way I have found is based on one of Hadley's examples using pmap:
iris %>%
mutate(Max.Len= purrr::pmap_dbl(list(Sepal.Length, Petal.Length), max))
Using this approach, you can give an arbitrary number of arguments to the function (.f) ...
NodeJS / Express: what is “app.use”?
...P server object. The method is defined as part of Connect that Express is based upon.
Update Starting with version 4.x, Express no longer depends on Connect.
The middleware functions that were previously included with Express are now in separate modules; see the list of middleware functions.
...
Junit - run set up method once
...venient for some tests that need instance of test case. For example Spring based tests that use @Autowired to work with services defined in spring context.
In this case I personally use regular setUp() method annotated with @Before annotation and manage my custom static(!) boolean flag:
private sta...
How does Apple know you are using private API?
...s such as UITouch._phase (which could be the cause of rejection of Three20-based apps last few months.)
3. Listing Objective-C selectors, or strings
Objective-C selectors are stored in a special region of the binary, and therefore Apple could extract the content from there, and check if you've us...
Efficiently test if a port is open on Linux?
...
The -z flag is not available in the nmap based ncat which most recent distros ship with: Fedora, Centos, etc. (nmap-ncat-6.01-9.fc18.x86_64)
– Zack
Dec 20 '15 at 14:13
...
Scanner vs. BufferedReader
As far I know, the two most common methods of reading character-based data from a file in Java is using Scanner or BufferedReader . I also know that the BufferedReader reads files efficiently by using a buffer to avoid physical disk operations.
...
ExpandableListView - hide indicator for groups with no children
...
Based on StrayPointer's answer and the code from the blog, you can simplify the code even more:
In your xml add the folowing to ExpandableListView:
android:groupIndicator="@android:color/transparent"
Then in the Adapter y...
How to get number of rows using SqlDataReader in C#
...ecuting the query, perhaps in a multi-result query so you only hit the database once.
– flipdoubt
Sep 5 '09 at 13:29
14
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How do I get the difference between two Dates in JavaScript?
... to get the difference, just subtract the two dates.
To create a new date based on the difference, just pass the number of milliseconds in the constructor.
var oldBegin = ...
var oldEnd = ...
var newBegin = ...
var newEnd = new Date(newBegin + oldEnd - oldBegin);
This should just work
EDIT: Fi...
Rounding up to next power of 2
...
Check the Bit Twiddling Hacks. You need to get the base 2 logarithm, then add 1 to that. Example for a 32-bit value:
Round up to the next highest power of 2
unsigned int v; // compute the next highest power of 2 of 32-bit v
v--;
v |= v >> 1;
v |= v >> 2;
v ...