In the R package ModelMetrics, the auc score as shown in the documentation takes only two inputs;  aucScore &lt;- auc(actual=actuallabels, predicted=predictedlabels)  where the inputs are pretty self explanatory. However, how is the AUC score even calculated here? From my understanding, do we not need the class "probabilities" (scores) produced from the model in order to graph the ROC curve in the first place? Each point on the ROC curve is the TPR vs. the FPR, at varying thresholds of class "probabilities" to trigger a "positive" prediction, if my understanding is correct. So how can we chart the ROC curve and find the area under said curve if we don't have the class probabilities to derive each point on the ROC curve itself? Based off labels alone, I would find that it would be impossible to find this unless there's some underlying estimation going on.  I've also noticed that many other packages also compute the area under the ROC curve by taking only two vectors of labels with seemingly no class probabilities.  Thanks.
I am interested in calculating area under the curve (AUC), or the c-statistic, by hand for a binary logistic regression model.  For example, in the validation dataset, I have the true value for the dependent variable, retention (1 = retained; 0 = not retained), as well as a predicted retention status for each observation generated by my regression analysis using a model that was built using the training set (this will range from 0 to 1).  My initial thoughts were to identify the "correct" number of model classifications and simply divide the number of "correct" observations by the number of total observations to calculate the c-statistic. By "correct", if the true retention status of an observation = 1 and the predicted retention status is > 0.5 then that is a "correct" classification. Additionally, if the true retention status of an observation = 0 and the predicted retention status is &lt; 0.5 then that is also a "correct" classification. I assume a "tie" would occur when the predicted value = 0.5, but that phenomenon does not occur in my validation dataset. On the other hand, "incorrect" classifications would be if the true retention status of an observation = 1 and the predicted retention status is &lt; 0.5 or if the true retention status for an outcome = 0 and the predicted retention status is > 0.5. I am aware of TP, FP, FN, TN, but not aware of how to calculate the c-statistic given this information.
For what $n$ is $U_n$ cyclic? Find all solutions of the equality $y^2=x^3+23$ for integers $x,y$   I guess, that x cannot be even. because we can apply mod 4 test  say $x=2k$ then $y^2=8k^3+23\equiv3\mod(4)$   but, this is not possible, since the square of an integer is congruent to $0$ or $1$ $\mod (4)$  so $x$ is of the form $4k+3$ or $4k+1$  $x=4k+3$ is also not possible for the same reason but for the last case the test fails.  any hints ? How to delete blank lines starting from line 5 I have this:  sed -i '/^$/d' temp_spec.rb   which is stripping blank lines and works well.  How can I make it only do this for lines 5-999 (or ideally 5 to end-of-file).  I tried:  sed -n5,999 -i '/^$/d' temp_spec.rb sed '5,999!d/^$/d' temp_spec.rb   but neither worked (no errors). How do I transfer a file to my server using PuTTY? Why does `find` not delete the files it found? I'm trying to understand why the find command is not deleting files in one particular case. I've got the following command:  find C:\\path\\to\\Pictures\\pmcctv -name cap_*.jpg -o -name cap_*.ogg -o -name cap_*.flv -o -name cap_*.mp4 -o -name cap_*.webm -mtime +7   Which returns the files I would expect:  C:\path\to/Pictures/pmcctv/cap_20160915T193251_620067800.jpg C:\path\to/Pictures/pmcctv/cap_20160915T193322_742708800.jpg C:\path\to/Pictures/pmcctv/cap_20160916T081046_394767500.jpg C:\path\to/Pictures/pmcctv/cap_20160916T081125_615129600.jpg C:\path\to/Pictures/pmcctv/cap_20160916T081129_503678200.jpg C:\path\to/Pictures/pmcctv/cap_20160916T081255_842394600.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161008_693586800.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161012_749396800.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161043_774132200.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161150_497251900.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161154_437379600.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161337_350955300.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161341_452596000.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161412_870774000.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161443_969064400.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161554_468109900.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161558_378086000.jpg C:\path\to/Pictures/pmcctv/cap_20160916T161916_668433100.jpg   Now if I try to run the same command with -delete, the files are not deleted:  find C:\\path\\to\\Pictures\\pmcctv -name cap_*.jpg -o -name cap_*.ogg -o -name cap_*.flv -o -name cap_*.mp4 -o -name cap_*.webm -mtime +7 -delete   I've also tried with -exec rm, but they are also not deleted:  find C:\\path\\to\\Pictures\\pmcctv -name cap_*.jpg -o -name cap_*.ogg -o -name cap_*.flv -o -name cap_*.mp4 -o -name cap_*.webm -mtime +7 -exec rm {} \;   find returns no error and the files are owned by me with permissions 644.  Any idea what could be causing this?  (note: I've cut the commands to make it more readable but normally there's no line break) The question asks to compute:   $$\sum_{k=0}^{n-1}\dfrac{\alpha_k}{2-\alpha_k}$$   where $\alpha_0, \alpha_1, \ldots, \alpha_{n-1}$ are the $n$-th roots of unity.   I started off by simplifiyng and got it as:  $$=-n+2\left(\sum_{k=0}^{n-1} \dfrac{1}{2-\alpha_k}\right)$$  Now I was stuck. I can rationalise the denominator, but we know $\alpha_k$ has both real and complex components, so it can't be simplified by rationalising. What else can be done? I'm trying to create an item that can break certain blocks, but also has a colored name in 1.13.2   Here's the command I'm using.  /give iAugust minecraft:shears{display:{Name:"[{\"text\":\"Arcane Shears\",\"color\":\"aqua\",\"italic\":false,\"bold\":false}]CanDestroy:[minecraft:iron_bars]"}}   But it only has a colored name, and it can't break specific blocks. Break a previous commit into multiple commits Why can't I use a type argument in a type parameter with multiple bounds? So, I understand that the following doesn't work, but why doesn't it work?  interface Adapter&lt;E&gt; {}  class Adaptulator&lt;I&gt; {     &lt;E, A extends I &amp; Adapter&lt;E&gt;&gt; void add(Class&lt;E&gt; extl, Class&lt;A&gt; intl) {         addAdapterFactory(new AdapterFactory&lt;E, A&gt;(extl, intl));     } }   The add() method gives me a compile error, "Cannot specify any additional bound Adapter&lt;E&gt; when first bound is a type parameter" (in Eclipse), or "Type parameter cannot be followed by other bounds" (in IDEA), take your pick.  Clearly you're just Not Allowed to use the type parameter I there, before the &amp;, and that's that. (And before you ask, it doesn't work if you switch 'em, because there's no guarantee that I isn't a concrete class.) But why not? I've looked through Angelika Langer's FAQ and can't find an answer.  Generally when some generics limitation seems arbitrary, it's because you've created a situation where the type system can't actually enforce correctness. But I don't see what case would break what I'm trying to do here. I'd say maybe it has something to do with method dispatch after type erasure, but there's only one add() method, so it's not like there's any ambiguity...  Can someone demonstrate the problem for me? File names for JSP include directive to avoid compilation of them What's the best way to take a segment out of a text file? What's a good way of extracting say, lines 20 -45 out of a huge text file. Non-interactively of course! Is it normal to get hundreds of break-in attempts per day? I just checked my server's /var/log/auth.log and found that I'm getting over 500 failed password/break-in attempt notifications per day! My site is small, and its URL is obscure. Is this normal? Should I be taking any measures? Set horizontal width on custom listings environment I want to create a custom listings environment and want to set its width as something like 90% of textwidth, centred.  Per an  for algorithms, the first thing I tried was to embed the listing in a minipage environment. However, . I found a way to still make standard environment work, but it requires to use the escape command every time before ending the environment.  The second thing I tried was this latter command, but as far as I can see, it doesn't offer a feature to set the width of the listing or centre it.  \documentclass{article} \usepackage{listings} \usepackage{lipsum}   \lstnewenvironment{queryl} %% APPROACH 1  {\lstset{frame=shadowbox,escapechar=`}}  {}  \newenvironment{query} %% APPROACH 2  {\begin{minipage}{4cm}\centering\begin{queryl}}  {\end{queryl}\end{minipage}}   \begin{document} %% APPROACH 1 Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis. \begin{queryl} begin { do nothing } end ; \end{queryl} Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis.  %% APPROACH 2 Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis.  \begin{query} begin { do nothing } end ;`%&lt;- needs escape-to-LaTeX character to work \end{query}  Lorem ipsum dolor sit amet, consectetuer adipiscing elit. Ut purus elit, vestibulum ut, placerat ac, adipiscing vitae, felis. \end{document}     One can note that for the first environment, the frame extends beyond the width of the text. Also, puzzlingly the minipage environment doesn't seem to want to centre and swallows space (though I guess I could perhaps at least get that to work with tinkering).  In any case, does anyone have any ideas on how to set a width for a custom listings environment and centre it without requiring use of the escape character each time to end the environment? On the one hand, I see very few posts in the review queue when I visit.  On the other hand, I see a lot of pretty awful first posts sitting on the front page.  This leads me to suspect that robo-reviewers are blowing through the queue.  Given how empty the queue is, could you please increase the number of people who have to check in before a post leaves the queue?  Of course, some honey-pot solution to detect and disable the auto-clickers would be even better. How do you use the Dungeon Defender's Portal Gun? The topic pretty much sums up my question. I have not yet figured out how the gun operates aside from the fact that it creates Portal portals. The weapon description indicates that it deals 250+ base damage, but how is that damage applied to the monsters? sometimes when writing mathematical expression with partial derivatives, one needs to write a vertical bar afterwards and write the value at the which the partial derivatives are being computed as subscripts. See for example the bottom post here:    However, the \mid symbol doesn't produce a tall bar that corresponds to the size of the partial derivatives term. Is there a way to have a taller bar?   PS: Some other posts here mention \middle| but this doesn't compile on my computer.  Thanks in advance.... Plot electric potential and field What's the difference between an id and a class? Ask question post button remains disabled I've noticed this twice in the last ~2 weeks or so. The &quot;post your question&quot; button can remain disabled for some reason even when your question is shown as &quot;ready to publish&quot;. I.e., you've gotten to the &quot;review&quot; page after the initial edit. If I remember correctly, one case was on Stack Overflow, and the other was on . I'm not sure what exact scenario leads up to this. I haven't paid attention to the button until the last step when I'm ready to click it. The workaround has been to reload the page. (I copied my content for safe-keeping first.) This works, and the button then shows up as active. Afterwards, however, on both occasions, it forced me through the &quot;are you a human&quot; verification.  Update - this question itself did not exhibit this, nor did it do the .  Update - I'm using Chrome on Windows and am not sure what version it was when this happened.  It has  installed, but there aren't any scripts for any Stack Exchange sites.  It has  installed.  The virus scanner on the PC I probably was using was iPhone Apps in Waiting mode for the last 4 days I tried to download the "Dictionary Free" app from the App Store four days ago, but it's been stuck in "Waiting" ever since. I've tried everything: rebooting the phone, restoring from an iTunes backup, side-loading the app from iTunes, but nothing has worked.  When I turn Airplane Mode on and then off again, I get an alert popup that says "Unable to download application. It will be available for download when you log in to the iTunes Store on your computer".  I've tried what it recommends, but nothing seems to work.