Get checkbox state in JavaFx
What is a NullPointerException, and how do I fix it?
By accident, I messed up a configuration file. How do I recover the default version without reinstalling or affecting other things? I want to select the value from the dropdown I am testing www.paytm.com  In that I have filled in the mobile number but I am not able to focus and select the mobile operator which is present in the dropdown just after the phone number section.  I want to select 'vodafone' as the value from the dropdown.  How to do that using webdriver  Code I have written till now  `  public class MMT {   public static void main (String[] args)  {  System.setProperty("webdriver.chrome.driver","E:/som/chromedriver/chromedriver.exe");  WebDriver driver = new ChromeDriver();  driver.get("http://paytm.com");  driver.findElement(By.id("mobile-number")).sendKeys("9876543212");`   What should be my next steps? I have been wondering about the differences between model paramters and model hyperparameters, as well as what their categorization means for a learning problem.  Is the distinction between model parameters and hyperparameters only about reducing the complexity of the problem or are there implications for the 'model quality' to be considered?  Let's consider an example from (1, Eq. 2.43), a linear expansion of basis functions   $$f_\theta(x) = \sum_{m=1}^{M} \theta_m h_m(x), $$  where $h_m\:\forall m=1,...,M$ is some function of $x$, $\theta=[\theta_1,...,\theta_M]^\intercal$ is a vector of the parameters of the model and $M$ is the number of basis functions.   In my understanding, we would consider $\theta$ to contain the parameters of the model, while $M$ is a .  To quote the Wikipedia article of hyperparameter that I linked above:     In machine learning, a hyperparameter is a parameter whose value is   set before the learning process begins. By contrast, the values of   other parameters are derived via training.   It makes sense treating the values in $\theta$ as parameters that should be learned from the data, similar to the coefficients in a linear model - it is surely far more reliable  and  specifying them manually would be quite annoying, although it's not impossible. But what about $M$? It surely is easier to pick some integer value for it. But would it really be terrible to determine $M$ based on the data, too? Probably not, as that is what we would do if we search a grid of possible values for the best performing one.   Let's consider the above basis expansion model and choose Gaussian kernel functions to serve as basis functions. As the Kernel itself has parameters too  this makes the problem a bit more complicated.  $$f_\theta(x) = \sum_{m=1}^{M}\theta_m K_{\lambda_m}(\mu_m,x), $$ with $\mu_1,...,\mu_m$ being the location of the kernels and $\lambda_1,...,\lambda_m$ their scales/bandwidths.  Friedman et al. write in (1, p. 36)        "In general we would like the data to dictate them as well. Including   these as parameters changes the regression problem from a   straightforward linear problem to a combinatorially hard nonlinear   problem. In practice, shortcuts such as greedy algorithms or two stage processes are used."   I see that if we were to treat $M$, $\theta_1 ... \theta_M$, $\mu_1 ... \mu_M$ and $\lambda_1 ... \lambda_M$, as model parameters, this problem would be really complex, especially with the choice of $M$ determining the number of the other parameters. But what if we simplify the model definition - let us for example use the same scale/bandwidth for each kernel, that gives us only one parameter $\lambda$. Furthermore, let's say we specify $\mu_1 ... \mu_M$ based on some heuristic, which would mean we treat it as a hyperparameter.  This gives us   $$f_{\theta,\lambda}(x) = \sum_{m=1}^{M}\theta_m K_\lambda(\mu_m,x), $$  Besides increased complexity of the involved optimization problem, does treating $\lambda$ as a parameter rather than a hyperparameter have other negative or undesired effects?      (1) Friedman, Jerome, Trevor Hastie, and Robert Tibshirani. The   elements of statistical learning. Vol. 1. No. 10. New York: Springer   series in statistics, 2001. Why don't researchers request payment for refereeing? (In, On or At) GitHub? What's the difference between say:     "The project will be on GitHub",      "The project will be in GitHub" and      "The project will be at GitHub"? Do we have more history for cd? There are several Q&amp;A threads that explain how to download youtube videos using the terminal.  However, I would also like to learn how to extract the video's soundtracks as MP3 files--also using only the terminal.  Answers briefly explaining how to use youtube-dl or other similar utilities before explaining how to extract the MP3 would be ideal for the sake of having all the information in one place--even though this aspect has been covered in other posts. We noticed that lots of bugs in our software developed in C# (or Java) cause a NullReferenceException.  Is there a reason why "null" has even been included in the language?  After all, if there were no "null", I would have no bug, right?  In other words, what feature in the language couldn't work without null? Reference — What does this symbol mean in PHP? Does Time Machine backup programs like Photoshop and iWork? Can you explain the "Axiom of choice" in simple terms? How to tell if a set of vectors spans a space? I want to know if the set $\{(1, 1, 1), (3, 2, 1), (1, 1, 0), (1, 0, 0)\}$ spans $\mathbb{R}^3$. I know that if it spans $\mathbb{R}^3$, then for any $x, y, z, \in \mathbb{R}$, there exist $c_1, c_2, c_3, c_4$ such that $(x, y, z) = c_1(1, 1, 1) + c_2(3, 2, 1) + c_3(1, 1, 0) + c_4(1, 0, 0)$.  I've looked around the internet, but all the answers I found involve setting up a matrix and finding the determinant, and I can't do that here because my matrix isn't square. What am I missing here? Does option "-h" for "ls" display size in MB or MiB and is it consistent over Unix-based systems? If $H \leq G$ and $[G:H]! \leq |G|$ then $G$ is not simple In fact, I would like to ask more general question -- &quot;what does write permission for a directory allow you to do exactly?&quot; -- but let's approach it with a concrete example. It is a long question, if you are in a hurry read the bold -- it should cover the main part. Different sources (, , ) say something similar to the following on the directory permissions:  r, read -- reading of the directory's content (filenames inside) w, write -- changing the directory's attributes (e.g. modification time) and creating/renaming/removing entries inside x, search -- accessing files inside, you have access to the inode of the file, hence you can reach it's actual content  My problem is with the description of w. What directory's attributes does it give you access to? I cannot create/rename/remove a file inside a directory with only write permission: I make a directory (tdir/) and a file inside (afile), chmod -x-r tdir/, mv tdir/afile tdir/af, rm tdir/afile, touch tdir/newfile -- all fail with permission denial, unless I set x permission to the directory as well. And x alone doesn't give you the permission to create/rename/remove files inside the directory. In order to do that you need both x and w. But touch tdir does change the modification time of the directory with w only. I would rephrase the sources above this way for the compliance with the issue: a directory's r allows you to see the filenames inside, but no access to the actual file (to the inode); x gives you access to the inodes of the files (which means you can see their permissions and, according to it, have access to the contents), but you still cannot change anything in the directory; directory is actually some sort of a file and to change something in it you need the w permission. Thus, when you are changing something in the directory you need w permission. If your change requires inodes of the files in the directory -- you need x as well. It explains why you cannot remove a file inside a directory with w only: when removing a file you need to reduce the link count of the inode by 1 -- you need to know the inode -- thus you need x for the directory. But why do you need x for creating (you could ask the system to create a file without exposing the inode?) and renaming/moving the file (when you move a file you don't change it in any way, you only change the records inside the directories and their inode counts?)? Maybe it is just an implementation thing? I.e. indeed you don't need the inode for renaming/creating files -- you need only filenames and w permission; but inode and filename constitute one record in the directory; thus changing the filenames = changing the records = kind of accessing the inodes. And also what attributes do directories have besides modification time, permissions and files records? What else in the directory can you change with w only? What plot points are missing in the Harry Potter movies that are in the novels? What's the right way to represent phone numbers? Creating A Bootable USB Of Windows 8.1 On OS X? Reasons for wanting create such a usb include:   PC is unbootable and you want to prepare a bootable USB using the ISO file that you have on your external hard drive. to install Windows 8.1 on Mac without Boot Camp.   What are the necessary steps to create such a Windows 8.1 bootable usb on a Mac ? What is "my guy syndrome" and how do I handle it? Why does an open interval NOT have measure zero?