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How can I remove all objects but one from the workspace in R?
I have a workspace with lots of objects and I would like to remove all but one. Ideally I would like to avoid having to type rm(obj.1, obj.2... obj.n) . Is it possible to indicate remove all objects but these ones ?
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How to check if element has any children in Javascript?
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A couple of ways:
if (element.firstChild) {
// It has at least one
}
or the hasChildNodes() function:
if (element.hasChildNodes()) {
// It has at least one
}
or the length property of childNodes:
if (element.childNodes.length > 0) { // Or just `if (element.childNodes.length)...
Two single-column indexes vs one two-column index in MySQL?
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If you have two single column indexes, only one of them will be used in your example.
If you have an index with two columns, the query might be faster (you should measure). A two column index can also be used as a single column index, but only for the column listed fi...
C++ : why bool is 8 bits long?
... I'm wondering why the bool type is 8 bits long (on my system), where only one bit is enough to hold the boolean value ?
6 ...
How to make the division of 2 ints produce a float instead of another int?
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Just cast one of the two operands to a float first.
v = (float)s / t;
The cast has higher precedence than the division, so happens before the division.
The other operand will be effectively automatically cast to a float by the comp...
What's better to use in PHP, $array[] = $value or array_push($array, $value)?
...enchmarks, but I personally feel like $array[] is cleaner to look at, and honestly splitting hairs over milliseconds is pretty irrelevant unless you plan on appending hundreds of thousands of strings to your array.
Edit: Ran this code:
$t = microtime(true);
$array = array();
for($i = 0; $i < 1000...
Could not find com.google.android.gms:play-services:3.1.59 3.2.25 4.0.30 4.1.32 4.2.40 4.2.42 4.3.23
...your SDK Manager.
Also be aware that there might be 2 SDK installations - one coming from AndroidStudio and one you might have installed. Better consolidate this to one installation - this is a common pitfall - that you have it installed in one installation but it fails when you build with the othe...
How to escape double quotes in JSON
I'm trying to show double quotes but it shows one of the backslashes:
7 Answers
7
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Thread vs ThreadPool
...e there and why should I consider using a thread from the pool rather than one I've explicitly created? I'm thinking specifically of .NET here, but general examples are fine.
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Intellij IDEA Java classes not auto compiling on save
...does in the background, but it takes Intellij about 3-4 seconds to compile one small change in one single class. Even the "Compile 'StartController.java'" meaning one class only takes 3-4 seconds. Eclipse does this in less than 100 milliseconds. I will test the eclipse mode plugin again and decide w...