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Django select only rows with duplicate field values
...viously had a bug on this (might have been fixed in recent versions) where if you don't specify a fieldname for the Count annotation to saved as, it defaults to [field]__count. However, that double-underscore syntax is also how Django interprets you wanting to do a join. So, essentially when you try...
What does T&& (double ampersand) mean in C++11?
...bs Jul 13 '14 at 16:12
The biggest difference between a C++03 reference (now called an lvalue reference in C++11) is that it can bind to an rvalue like a temporary without having to be const. Thus, this syntax is now legal:
T&& r = T();
rvalue references primarily provide for the follo...
Pragma in define macro
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If you're using c99 or c++0x there is the pragma operator, used as
_Pragma("argument")
which is equivalent to
#pragma argument
except it can be used in macros (see section 6.10.9 of the c99 standard, or 16.9 of the c++0...
“Debug certificate expired” error in Eclipse Android plugins
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There is now a bug tracker issue requesting this to be fixed. Please vote for it. code.google.com/p/android/issues/detail?id=15370
– Manfred Moser
Mar 9 '11 at 19:52
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Average of 3 long integers
... can give a result that is off by one, namely rounded up rather than down, if negative values for the variables are allowed. For instance if x,y are positive multiples of 3, and z is -2, you get (x+y)/3 which is too much.
– Marc van Leeuwen
May 30 '14 at 15:15
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Get ffmpeg information in friendly way
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Now is possible to use -progress - to print friendly info formatted by key=value.
ffmpeg -i video.mp4 .......-s 1920x1080 -progress - -y out.mp4
speed=5.75x
frame=697
fps=167.7
stream_0_0_q=39.0
bitrate=2337.0kbits/s
total...
How to git-cherry-pick only changes to certain files?
...tively with git reset -p HEAD. It's the equivalent of add -p but very few know that it exists.
– Patrick Schlüter
Mar 14 '17 at 9:09
2
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How do I efficiently iterate over each entry in a Java Map?
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To summarize the other answers and combine them with what I know, I found 10 main ways to do this (see below). Also, I wrote some performance tests (see results below). For example, if we want to find the sum of all of the keys and values of a map, we can write:
Using iterator and Ma...
How does Stack Overflow generate its SEO-friendly URLs?
...low question How can I remove accents on a string?.
The case conversion is now also optional.
public static class Slug
{
public static string Create(bool toLower, params string[] values)
{
return Create(toLower, String.Join("-", values));
}
/// <summary>
/// Creat...
How does python numpy.where() work?
..., True, True]], dtype=bool)
This is the same reason why something like if x > 5: raises a ValueError if x is a numpy array. It's an array of True/False values, not a single value.
Furthermore, numpy arrays can be indexed by boolean arrays. E.g. x[x>5] yields [6 7 8], in this case.
Hones...