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How to check if hex color is “too black”?
...Int(c, 16); // convert rrggbb to decimal
var r = (rgb >> 16) & 0xff; // extract red
var g = (rgb >> 8) & 0xff; // extract green
var b = (rgb >> 0) & 0xff; // extract blue
var luma = 0.2126 * r + 0.7152 * g + 0.0722 * b; // per ITU-R BT.709
if (luma < 40) {
...
RegEx to parse or validate Base64 data
...sion to match Base64 encoded words, you can use the following:
^(?:[A-Za-z0-9+/]{4})*(?:[A-Za-z0-9+/]{2}==|[A-Za-z0-9+/]{3}=)?$
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What is the difference between 0.0.0.0, 127.0.0.1 and localhost?
...ekyll and Vagrant on my mac. I found that Jekyll server will bind to 0.0.0.0:4000 instead of 127.0.0.1:4000 . Also gem server will bind to this address by default. I can still visit it via http://localhost:port . But for Jekyll , it seems that the default setting (e.g. 0.0.0.0:4000) req...
How to access the ith column of a NumPy multidimensional array?
...
>>> test[:,0]
array([1, 3, 5])
Similarly,
>>> test[1,:]
array([3, 4])
lets you access rows. This is covered in Section 1.4 (Indexing) of the NumPy reference. This is quick, at least in my experience. It's certainly muc...
What is the difference between 127.0.0.1 and localhost
... still have to do an actual lookup of localhost somewhere.
If you use 127.0.0.1, then (intelligent) software will just turn that directly into an IP address and use it. Some implementations of gethostbyname will detect the dotted format (and presumably the equivalent IPv6 format) and not do a looku...
How to check if all elements of a list matches a condition?
I have a list consisting of like 20000 lists. I use each list's 3rd element as a flag. I want to do some operations on this list as long as at least one element's flag is 0, it's like:
...
Get operating system info
...
202
The code below could explain in its own right, how http://thismachine.info/ is able to show whi...
What are the main uses of yield(), and how does it differ from join() and interrupt()?
...nd Java 6.
In Java 5, Thread.yield() calls the Windows API call Sleep(0). This
has the special effect of clearing the current thread's quantum and
putting it to the end of the queue for its priority level. In other
words, all runnable threads of the same priority (and those of greater
p...
What is the maximum length of latitude and longitude? [closed]
...
If latitude coordinate is reported as -6.3572375290155 or -63.572375290155 in decimal degrees then you could round-off and store up to 6 decimal places for 10 cm (or 0.1 meter) precision.
Overview
The valid range of latitude in degrees is -90 and +90 for the southern and nor...
Applying a function to every row of a table using dplyr?
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202
As of dplyr 0.2 (I think) rowwise() is implemented, so the answer to this problem becomes:
iri...