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What's the fastest way to merge/join data.frames in R?
...he first example sqldf is 3x slower than data.table and in the second its 200x faster than plyr and 100 times faster than data.table. Below we show the input code, the output timings for the merge and the output timings for the aggregate. Its also worthwhile noting that sqldf is based on a databa...
Are Javascript arrays sparse?
...
40
How exactly JavaScript arrays are implemented differs from browser to browser, but they generall...
How are the points in CSS specificity calculated
... algorithm is 256 or 28.
What this means is that a style specified with 0 ids and 256 class-names will over-ride a style specified with just 1 id. I tested this out with some fiddles:
255 classes are not enough to override 1 id
...but 256 classes are enough to override 1 id
...and 256 tag-name...
How to validate an email address using a regular expression?
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+50
The fully RFC 822 compliant regex is inefficient and obscure because of its length. Fortunately, RFC 822 was superseded twice and the...
Connect to a locally built Jekyll Server using mobile devices in the LAN
..., a WEBrick server is set up and the site can be accessed from localhost:4000 on this particular PC.
2 Answers
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std::vector performance regression when enabling C++11
...ck(Item());)
$ g++ -std=c++11 -O3 -flto regr.cpp && perf stat -r 10 ./a.out
Performance counter stats for './a.out' (10 runs):
35.426793 task-clock # 0.986 CPUs utilized ( +- 1.75% )
4 context-switches # 0.116 K/sec ...
How to grant remote access to MySQL for a whole subnet?
... |
edited Nov 14 '17 at 20:33
answered Jul 31 '12 at 15:01
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Two color borders
...utline is inside of the shadow; in FireFox it is outside, so -moz-outline: 0 is useful to ensure that you don't get a gnarly line around your beautiful CSS drop shadow).
.someclass {
border: 1px solid blue;
outline: 1px solid darkblue;
}
Edit: Some people have remarked that outline doesn't ji...
Why is address zero used for the null pointer?
...s a pointer with the value zero if it can't get me memory; I use if (p != 0) all the time to make sure passed pointers are valid, etc.
...
CSS: bolding some text without changing its container's size
...h a little compromise, I used text-shadow instead.
li:hover {text-shadow:0px 0px 1px black;}
Here's a working example:
body {
font-family: segoe ui;
}
ul li {
display: inline-block;
border-left: 1px solid silver;
padding: 5px
}
.textshadow :hover {
text-shadow: 0px 0p...