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Select first 4 rows of a data.frame in R
...
Use head:
dnow <- data.frame(x=rnorm(100), y=runif(100))
head(dnow,4) ## default is 6
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Cross-platform way of getting temp directory in Python
...iable.
The directory named by the TMP environment variable.
A platform-specific location:
On RiscOS, the directory named by the Wimp$ScrapDir environment variable.
On Windows, the directories C:\TEMP, C:\TMP, \TEMP, and \TMP, in that order.
On all other platforms, the directories /tmp, /var/tmp, a...
How to monitor the memory usage of Node.js?
...ay of 10M elements consumers approximately 80MB (take a look at heapUsed).
If you look at V8's source code (Array::New, Heap::AllocateRawFixedArray, FixedArray::SizeFor), then you'll see that the memory used by an array is a fixed value plus the length multiplied by the size of a pointer. The latter...
Scala how can I count the number of occurrences in a list
...-> 3, apple -> 3)
The question asks how to find the count of a specific item. With this approach, the solution would require mapping the desired element to its count value as follows:
s.groupBy(identity).mapValues(_.size)("apple")
...
How to disable admin-style browsable interface of django-rest-framework?
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'rest_framework.permissions.IsAuthenticatedOrReadOnly',
)
}
If you would like to completely hide the API unless the user is logged in, you could also use IsAuthenticated.
FYI: This will also remove the form from the HTML browseable API as it responds to permissions. When an authentic...
How to get the latest tag name in current branch in Git?
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This answer (and probably the others) runs into trouble if you have two tags pointing to the same commit. Unless the tags are annotated tags, I think there is no way for git to distinguish which of the two was created earlier.
– Paul Lynch
J...
Sharing src/test classes between modules in a multi-module maven project
...gin>
<groupId>org.apache.maven.plugins</groupId>
<artifactId>maven-jar-plugin</artifactId>
<version>2.2</version>
<executions>
<execution>
<goals>
<goal>test-jar</goal>
</goals>
</execut...
What is the 'override' keyword in C++ used for? [duplicate]
...o the parent class/interface) is removed (not alternated). This is useful if the subclass is expecting a callback but it will never happen due to the library change, etc.
– Hei
Mar 11 '18 at 5:32
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How to loop through a HashMap in JSP?
...r a ServletContextListener to place the ${countries} in the desired scope. If this list is supposed to be request-based, then use the Servlet's doGet():
protected void doGet(HttpServletRequest request, HttpServletResponse response) {
Map<String, String> countries = MainUtils.getCountries()...
Java reflection - impact of setAccessible(true)
... the accessibility back to its original state is not needed.
However...
If you want your calls to field.setAccessible(true) to be persistent you need to use underlying methods in java.lang.Class and java.lang.reflect.Field. The public facing methods send you copies of the Field instance, so it "f...