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How to check if object (variable) is defined in R?

... heh. Happens to me all the time when I am testing out examples before posting, Gavin or Josh have already answered it. – Maiasaura Feb 20 '12 at 22:17 ...
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mingw-w64 threads: posix vs win32

I'm installing mingw-w64 on Windows and there are two options: win32 threads and posix threads. I know what is the difference between win32 threads and pthreads but I don't understand what is the difference between these two options. I doubt that if I will choose posix threads it will prevent me fro...
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How to change the font size on a matplotlib plot

How does one change the font size for all elements (ticks, labels, title) on a matplotlib plot? 12 Answers ...
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java.sql.SQLException: Incorrect string value: '\xF0\x9F\x91\xBD\xF0\x9F…'

...ead: For a supplementary character, utf8 cannot store the character at all, while utf8mb4 requires four bytes to store it. Since utf8 cannot store the character at all, you do not have any supplementary characters in utf8 columns and you need not worry about converting characters or losi...
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What's the difference between using CGFloat and float?

I tend to use CGFloat all over the place, but I wonder if I get a senseless "performance hit" with this. CGFloat seems to be something "heavier" than float, right? At which points should I use CGFloat, and what makes really the difference? ...
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How do I run IDEA IntelliJ on Mac OS X with JDK 7?

...will not work with JDK 1.7 on Mac. At the moment you must have JDK 1.6 installed so that you can run IDEA 11 and older versions. share | improve this answer | follow ...
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js/php判断终端类型:PC访问、手机访问、微信访问 - 更多技术 - 清泛网 - ...

...里提供php的判断方法: // 判断是否是手机端 function is_mobile() { // 如果有HTTP_X_WAP_PROFILE则一定是移动设备 if (isset($_SERVER['HTTP_X_WAP_PROFILE'])) { return true; } // 如果via信息含有wap则一定是移动设备,部分服务商...
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django change default runserver port

... You can't run the development server programmatically, so a custom command won't work unless it calls the shell using something like call. If this solution works for you please make sure to mark it as solved. – Pablo Albornoz May 13 '1...
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Scala @ operator

...n itself? That would be accomplished with this: o match { case x @ Some(_) => println(x) case None => } Note that @ can be used at any level, not just at the top level of the matching. share | ...
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Plot two histograms on single chart with matplotlib

...dom import numpy from matplotlib import pyplot x = [random.gauss(3,1) for _ in range(400)] y = [random.gauss(4,2) for _ in range(400)] bins = numpy.linspace(-10, 10, 100) pyplot.hist(x, bins, alpha=0.5, label='x') pyplot.hist(y, bins, alpha=0.5, label='y') pyplot.legend(loc='upper right') pyplot....