Slope layer with false results in QGIS?
Getting incorrect slope values from an ASTER DEM in QGIS?
How does mission progress work in multiplayer? Kinematic Viscosity Can I convert flat bar to drop bars on a hybrid bike Logical XOR operator in C++? Does the speed of light vary in non-inertial frames? can't read from SQlite database Select values that meet different conditions on different rows? This is a very basic query I can't figure out....  Let's say I have a two column table like this:  userid  |  roleid --------|--------    1    |    1    1    |    2    1    |    3    2    |    1   I want to get all distinct userids that have roleids 1, 2 AND 3.  Using the above example, the only result I want returned is userid 1.  How do I do this? I have an existing windows application, for which I have decided to create a Mac version. The problem is that the current UI involves a lot of buttons, tabbed panels, multiple windows etc.  This UI had been rated as intuitive and easy to use and straightforward  by many customers and editors. But a beginner (very less experience) may find in confusing a little, but it has been complemented with tutorial.      When creating the Macintosh variant, should I focus on creating a simplified and minimalistic UI (this does not mean the current UI is complex, but I think Mac user's prefer a simple UI right?) or should I try to copy the exact same thing?  By reducing the UI some of the features may be missing. But it can be added later if needed. Should I focus on a fresh approach (this is easier rather than copying the complex UI pattern) or should I go with the old recognized setup? Update to latest version of java after ppa is discontinued Proving $\mathbb{Q}$ isn't homeomorphic to $\mathbb{Z}$ Preserving signatures of decorated functions Suppose I have written a decorator that does something very generic. For example, it might convert all arguments to a specific type, perform logging, implement memoization, etc.  Here is an example:  def args_as_ints(f):     def g(*args, **kwargs):         args = [int(x) for x in args]         kwargs = dict((k, int(v)) for k, v in kwargs.items())         return f(*args, **kwargs)     return g  @args_as_ints def funny_function(x, y, z=3):     """Computes x*y + 2*z"""     return x*y + 2*z  &gt;&gt;&gt; funny_function("3", 4.0, z="5") 22   Everything well so far. There is one problem, however. The decorated function does not retain the documentation of the original function:  &gt;&gt;&gt; help(funny_function) Help on function g in module __main__:  g(*args, **kwargs)   Fortunately, there is a workaround:  def args_as_ints(f):     def g(*args, **kwargs):         args = [int(x) for x in args]         kwargs = dict((k, int(v)) for k, v in kwargs.items())         return f(*args, **kwargs)     g.__name__ = f.__name__     g.__doc__ = f.__doc__     return g  @args_as_ints def funny_function(x, y, z=3):     """Computes x*y + 2*z"""     return x*y + 2*z   This time, the function name and documentation are correct:  &gt;&gt;&gt; help(funny_function) Help on function funny_function in module __main__:  funny_function(*args, **kwargs)     Computes x*y + 2*z   But there is still a problem: the function signature is wrong. The information "*args, **kwargs" is next to useless.  What to do? I can think of two simple but flawed workarounds:  1 -- Include the correct signature in the docstring:  def funny_function(x, y, z=3):     """funny_function(x, y, z=3) -- computes x*y + 2*z"""     return x*y + 2*z   This is bad because of the duplication. The signature will still not be shown properly in automatically generated documentation. It's easy to update the function and forget about changing the docstring, or to make a typo. [And yes, I'm aware of the fact that the docstring already duplicates the function body. Please ignore this; funny_function is just a random example.]  2 -- Not use a decorator, or use a special-purpose decorator for every specific signature:  def funny_functions_decorator(f):     def g(x, y, z=3):         return f(int(x), int(y), z=int(z))     g.__name__ = f.__name__     g.__doc__ = f.__doc__     return g   This works fine for a set of functions that have identical signature, but it's useless in general. As I said in the beginning, I want to be able to use decorators entirely generically.  I'm looking for a solution that is fully general, and automatic.  So the question is: is there a way to edit the decorated function signature after it has been created?  Otherwise, can I write a decorator that extracts the function signature and uses that information instead of "*kwargs, **kwargs" when constructing the decorated function? How do I extract that information? How should I construct the decorated function -- with exec?  Any other approaches? machine wakes only on local magic packet I've got a Debian server, which I would like to wake up remotely using a tool like wakeonlan.  I have assigned the server a static internal IP 192.168.0.14 and set up the appropriate port forwarding in the router (which otherwise has a very limited admin interface).  When I am logged in to the same network, I can wake the server using the subnet IP, but I cannot wake the server using the public IP of the router.  What I do not understand: When the server is running and I listen on the server with netcat nc -ulv -p 9, I can see the packet coming in in both cases (both when sending to the subnet IP and when sending to the public IP of the router).  If the packet arrives in both cases, why does the machine wake up only in one of them? Reload activity in Android How to select an element whose id is dynamic and keeps changing There is a type and search drodown which will appear after user type in the value. I need to click on the dropdown which contains the name of the drop down field.   The problem here is that there is no unique attribute present (No unique class, no unique name) &amp; the id keeps on changing after every login so cannot take id also. Proving $f(x,y,z)=\big(\frac{x}{a+x+y+z}, \frac{y}{a+x+y+z}, \frac{z}{a+x+y+z} \big)$ is injective Let $a\in \mathbb{R}$, $a\neq 0$, and $E=\{(x,y,z)\in \mathbb{R}^3:a+x+y+z\neq 0\}$ and $f:E\rightarrow \mathbb{R}^3$ defined by $$ f(x,y,z)=\big(\frac{x}{a+x+y+z}, \frac{y}{a+x+y+z}, \frac{z}{a+x+y+z} \big) $$ Show that $f$ is injective.    I've been trying to prove it directly by showing that if $f(x_1,y_1,z_1)=f(x_2,y_2,z_2)\Rightarrow$ $x_1=x_2, y_1=y_2,z_1=z_2$. But I get a system of equations which I'm find difficult to deal with. Any help would be greatly appreciated. Systemd backed tmpfs | How to specify /tmp size manually I mount /tmp on tmpfs using:  sudo systemctl enable tmp.mount sudo systemctl start tmp.mount   But this way /tmp takes up all the free RAM:  $ df -h /tmp Filesystem      Size  Used Avail Use% Mounted on tmpfs           3.9G   12K  3.9G   1% /tmp $   How do I tell systemd tmp.mount to use only 1G? I know I can alternatively not use systemd and manually add an entry to /etc/fstab and specify the size there. But I don't want to do that. I want to use systemd backed tmpfs. How to get div height to auto-adjust to background size? How do I get a div to automatically adjust to the size of the background I set for it without setting a specific height (or min-height) for it? Is it possible to make armour that can survive /kill? /kill is said to be infinity damage but I have a question can you really survive it in Java edition. However, it is possible that you can pretty much survive this if you are on Minecraft Java Edition in 1.8 or lower and you can just have resistance 5 and you will survive this but can you make armour that helps you survive in 1.16 and in java-edition. I know blender can display both orthographic and perspective projection. But, when we look at a cube in blender's viewport, I'm unable to distinguish by eye, if the projection in the viewport is a one-point, a two-point or a three-point perspective. What does blender use, and is this something changeable? What is the function represented by the power series $$ \sum_{k=2}^\infty\frac{x^k}{k(k-1)}\quad? $$  It looks like $\dfrac1{1-x}$ but I don't know.