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Retrieve only the queried element in an object array in MongoDB collection
...r to filter an array during projection, which has the benefit of including all matches, instead of just the first one.
db.test.aggregate([
// Get just the docs that contain a shapes element where color is 'red'
{$match: {'shapes.color': 'red'}},
{$project: {
shapes: {$filter: {
...
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 ...
Declaring a custom android UI element using XML
...
The Android Developer Guide has a section called Building Custom Components. Unfortunately, the discussion of XML attributes only covers declaring the control inside the layout file and not actually handling the values inside the class initialisation. The steps are as...
How to center text vertically with a large font-awesome icon?
...
I use icons next to text 99% of the time so I made the change globally:
.fa-2x {
vertical-align: middle;
}
Add 3x, 4x, etc to the same definition as needed.
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“open/close” SqlConnection or keep open?
...th static methods. Each of these methods opens/closes SQL connection when called:
6 Answers
...
Abstraction VS Information Hiding VS Encapsulation
...ften achieved through information hiding, which
is the process of hiding all of the secrets of object that do not
contribute to its essential characteristics.
In other words: abstraction = the object externally; encapsulation (achieved through information hiding) = the object internally,
Exam...
Adjust width and height of iframe to fit with content in it
...'iFrame1' );
resizeIFrameToFitContent( iFrame );
// or, to resize all iframes:
var iframes = document.querySelectorAll("iframe");
for( var i = 0; i < iframes.length; i++) {
resizeIFrameToFitContent( iframes[i] );
}
} );
</script>
<iframe src="usagelogs/defa...
Is there a working C++ refactoring tool? [closed]
...
Unfortunately, Refactor for C++ doesn't work well (if at all) with large codebases.
– Daniel Rose
May 4 '11 at 9:46
1
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Reading CSV files using C#
...sualBasic but it works in C# just as well - remember that at the end it is all just IL)
use the Microsoft.VisualBasic.FileIO.TextFieldParser class to parse CSV file
Here is the sample code:
using (TextFieldParser parser = new TextFieldParser(@"c:\temp\test.csv"))
{
parser.TextFieldType = Fiel...
Convert column classes in data.table
...hat is the idiomatic way of doing this for a subset of columns (instead of all of them)? I've defined a character vector convcols of columns. dt[,lapply(.SD,as.numeric),.SDcols=convcols] is almost instant while dt[,convcols:=lapply(.SD,as.numeric),.SDcols=convcols] almost freezes up R, so I'm guessi...