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Why is rbindlist “better” than rbind?
...t shines are
Fast vectorized merge of list of data.frames by row
Trouble converting long list of data.frames (~1 million) to single data.frame using do.call and ldply
These have benchmarks that show how fast it can be.
rbind.data.frame is slow, for a reason
rbind.data.frame does lots of check...
Principal component analysis in Python
...ution in which the out would be that image. IM having some difficulties in converting this code to c++ because I'm new in python :)
– Orvyl
Feb 28 '14 at 6:20
add a comment
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Why would iterating over a List be faster than indexing through it?
...use every time you are indexing it restarts from the beginning of the list and goes through every item. This means that your complexity is effectively O(N^2) just to traverse the list!
If instead I did this:
for(String s: list) {
System.out.println(s);
}
then what happens is this:
head ->...
How to use enum values in f:selectItem(s)
...
JSF has a builtin converter for enum, so this should do:
@ManagedBean
@ApplicationScoped
public class Data {
public Status[] getStatuses() {
return Status.values();
}
}
with
<h:selectOneMenu value="#{bean.question.stat...
Evenly space multiple views within a container view
... "as is" I had to reverse the multipliers (ej. the 3:1 from the first item converts to 1:3). Just throwing this out there if it helps anyone.
– Ces
May 12 '16 at 3:01
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Android custom dropdown/popup menu
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Update: To create a popup menu in android with Kotlin refer my answer here.
To create a popup menu in android with Java:
Create a layout file activity_main.xml under res/layout directory which contains only one button.
Filename: activity_main.xml
<Rela...
Where do I find the current C or C++ standard documents?
...he standard is maintained as LaTeX sources on Github. These sources can be converted to HTML using cxxdraft-htmlgen. The following sites maintain HTML pages so generated:
Tim Song - Current working draft - C++11 - C++14 - C++17
Eelis - Current working draft
Tim Song also maintains generated HTML...
How can I change my Cygwin home folder after installation?
...f %USERPROFILE% or C:\Users\$USERNAME. Of course, the Windows directory is converted to POSIX-style by Cygwin.
cygwin AD only: The user's home directory is set to the POSIX path given in the cygwinHome attribute from the cygwinUser auxiliary class. See also the section called “The cygwin schema”...
What is the lifetime of a static variable in a C++ function?
... is declared as static in a function's scope it is only initialized once and retains its value between function calls. What exactly is its lifetime? When do its constructor and destructor get called?
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After array_filter(), how can I reset the keys to go in numerical order starting at 0
...php "If no callback is supplied, all entries of array equal to FALSE (see converting to boolean) will be removed." And it should be common knowledge among PHP programmers that 0, null, false, '' and '0' all evaluate to false when coerced to boolean.
– madsen
M...