I have a binary dataset and I want to build a classifier. I understand that to monitor performance I need to split to training/test set and report accuracy or any other metrics that interest me on the test set. Now, I have a new example for which I do not know the label and I want to predict it using my classifier.  My question is: should I use the classifier that I built using the training set only or merge both training and test set, build a classifier based on all available data and then predict my new example while still reporting the accuracy based only on a the test set?
TL:DR: Is it ever a good idea to train an ML model on all the data available before shipping it to production? Put another way, is it ever ok to train on all data available and not check if the model overfits, or get a final read of the expected performance of the model?    Say I have a family of models parametrized by $\alpha$. I can do a search (e.g. a grid search) on $\alpha$ by, for example, running k-fold cross-validation for each candidate.   The point of using cross-validation for choosing $\alpha$ is that I can check if a learned model $\beta_i$ for that particular $\alpha_i$ had e.g. overfit, by testing it on the "unseen data" in each CV iteration (a validation set). After iterating through all $\alpha_i$'s, I could then choose a model $\beta_{\alpha^*}$ learned for the parameters $\alpha^*$ that seemed to do best on the grid search, e.g. on average across all folds.  Now, say that after model selection I would like to use all the the data that I have available in an attempt to ship the best possible model in production.  For this, I could use the parameters $\alpha^*$ that I chose via grid search with cross-validation, and then, after training the model on the full ($F$) dataset, I would a get a single new learned model $\beta^{F}_{\alpha^*}$   The problem is that, if I use my entire dataset for training,  I can't reliably check if this new learned model $\beta^{F}_{\alpha^*}$ overfits or how it may perform on unseen data. So is this at all good practice? What is a good way to think about this problem?
miktex-makepk - PK font HieroB could not be created I am depressed, after trying to install HieroTeX with MikTex 2.9 and TeXnicenter for four weeks without succeeding. I installed hieroglf, it works perfectly, but has only 60 signs. I followed the main advices, so I created a folder texmf-Local , throwed in  the content of HieroTex3.5 and Hiero-Type1.3.1.4 , put the axmf , mf and sty files where I think they belong, put that directory  texmf- local in the path searched by Miktex, updated map and file databases fo Miktex. Still the files can be compiled but Hiero fonts are not found.  Te main errors I can detect from log are the following:   " No file egypto.sty.tex found" and  "  "miktex-makepk - PK font HieroB could not be created." and similar for other fonts Thanks Is there a list of the names used for Sauron in Lord of the Rings? Why did Harime Nui's eye not heal? Why can't two series-connected diodes act as a BJT? Another form of the question is: will joining two diodes with wires (pn-np) make a transistor-equivalent?  I read that they are not equivalent, but why? Injecting variable values into javascript and HAML in RoR how to convert NTFS to ext4 in windows? How do I resize my current ubuntu partition? An $n$th root inequality: $\sqrt[n]{n} < 1 + \sqrt{2/n}$ Prove that for any positive integer $n$,       $$n^{1/n}  &lt; 1 + \sqrt{\frac{2}{n}}.$$   This due to Victor Linis, Eureka, Vol. 2, No. 2, February 1976, p. 29.   Hint:      Use the binomial theorem. Microsoft Edge missing in Start menu and pins Note: People have seem to have had issues doing this in Windows 10 pro, this could be because of Windows Updates. If the solution does not work, please use "Refresh your PC"  I have just upgraded to Windows 10 and had to switch to a Microsoft account while setting up Cortana.   Along the process, it asks me to sign out and sign back in, which I do. Then after signing back in, Microsoft Edge is missing. From the taskbar, and the "All Apps" section of the start menu.   This only occurs AFTER I have added my Microsoft account. And the only way is to open a .HTML file like this one:    (The name was from my Windows 7 Dualboot Install)  and please don't say "Just open the HTML file!" I need a proper solution to this. Basic desktop actions are not available on Ubuntu 20.04 In Ubuntu 20.04, on the desktop, there is a number of actions I wish I could do, such as, by order of importance :  use keyboard shortcuts such as select all, copy / paste. use drag &amp; drop with icons deactivate the &quot;mouse over&quot; highlight, and restrict the clicking area to only the icon, not the surrounding square  To put it simply, I'd like to have the exact same features as offered by the desktop of Ubuntu 18.04 (probably related to a specific version of GNOME, and not Ubuntu itself). Am I missing something obvious here? I actually see no reason why those actions are removed or deactivated on the desktop, since they all work in any Nautilus window. Number of $(0,1)$ $m\times n$ matrices with no empty rows or columns You know, some of us read right to left...  Certain sites like  and  have an obvious need for this, as Arabic and Hebrew are Right To Left (RTL) languages. Many answers on those sites cite the Torah and the Quran respectively. Directly quoting these sources properly requires RTL text. I am using an iPhone 6s with iOS 12.4 and a MacBook Pro mid2015 with macOS 10.14.6. Since recently (I am not exactly sure when it started), I cannot charge the phone with my computer anymore. As soon as I plug the phone in, it will play the charging sound repeatedly. The right-hand side port sometimes works, the lefthand side port never works. When I connect my old iPhone 5 (using the same cable), it charges without any issues. My iPad mini 4 shows the same issue.  Sometimes the "Do you trust this computer" setting flashes on the phone and disappears before I can click anything.   How can I fix this?  Update 1  Sometimes I get the Software Update dialogue in macOS. After approx. 2 minutes it shows the following:     Update 2  For some reason the issue disappeared for a while but is back now. Disabling "Settings" > "Touch ID &amp; Passcode" > "USB Accessoires" seems like it makes the problem a bit less bad, but not go away.  Update 3  This is driving me crazy. I upgraded to Mojave 10.14.3 mostly to get rid of the issue. It persists. Some more random information: Before logging in (Filevault pre-boot authentication), the phone will charge fine. Only when a user account is loaded, the issue appears. The likelihood of a successful connection increases with the battery state of the iPhone. Workaround 2 in my answer below suggest that this a "Trust issue" from the iPhone's side. I suppose the solution will have to be hidden somewhere there...    What I tried so far (will update):   Reset Privacy settings on iPhone Different (original, almost new Apple) lightning cables   Remove and add "iPhone USB" in Network Settings  SMC reset (), PRAM reset Upgrade to latest iOS 12.4 and MacOS 10.14.6 Automatically adding user and password to openvpn script I have a working script, which allows me to do a vpn connection. It looks like this:  openvpn --config VPNBook.com-OpenVPN-Euro1/vpnbook-euro1-tcp443.ovpn   All is good, but I have to input the publicly available vpn and password every time I run this script. (Don't worry, I'm not going to do banking or anything serious over a free VPN, this is more for learning).  This is the username and the password available publicly on their website:  Username: vpnbook  Password: he2qv5h   After firing up, the script prompts me for username and password which now I need to copy and paste.   Tue Aug 15 11:54:51 2017 library versions: OpenSSL 1.0.2l  25 May 2017, LZO 2.08 Enter Auth Username: vpnbook Enter Auth Password:    Is there a way of doing it so the script inputs the values on its own?  I tried echoing it, but it isn't that easy.  Or do I have to edit the command itself, somewhere in the files? If yes, can someone point me in the right direction for doing it? How many solutions $X^{10} - I=0$ has in $M_2(\mathbb{R})$? How many solutions $X^{10} - I=0$ has in $M_2(\mathbb{R})$? Where $M_2(\mathbb{R})$ denotes the set of $2 \times 2$ real matrices.  I absolutely have no idea of where I should start from. $I$ and $-I$ solve the equation, but are there any other non-trivial solutions? Are there infinitely many solutions? While attempting to delete a question which was answered by myself, and with no other answers, I got the following warning:     Delete this answered question?      We do not recommend deleting questions with answers because doing so   deprives future readers of this knowledge.      Repeated deletion of answered questions can result in your account   being blocked from asking. Are you sure you wish to delete?   I understand that deleting your question when someone else has answered it is effectively nullifying the effort that person put into that answer, which is bad. But is it bad if the only answer that's deleted along with your question is your own? If $f(\frac{1}{n})=0$ all $ n\to \mathbb{Z^{+}}$ then find $ f'(0)$? Let $f: \mathbb{R}\to \mathbb{R}$ be a twice differntiable function and $f(\frac{1}{n})=0$ all $n\in \mathbb{Z^{+}}$? then which of the statement (s) are correct from below.  (a)$f(0)=0$  (b)$f^{'}(0)=0$  (c)$f^{''}(0)=0$  (d)$f$ is a non zero polynomial  I tried of using Tyler series but I wasn't able to do this any help would be appreciated thank How to customize Latexian to use other TeX engines or biber? The Mac editor Latexian has built in methods for compiling using latex+dvips, pdflatex and xelatex.  Furthermore, it assumes bibtex and makeindex to deal with bibliographies and indexes, respectively.  How do I customize Latexian to use, e.g. LuaTeX for compiling or Biber for bibliographies? How should I address a potential FERPA violation by a professor? In the United States, federal law prohibits professors from releasing any student's grades to any party other than the student and any party whom the student authorizes to receive the grades.  One of my professors appears to be violating this law by uploading each student's lab grades in one file, which is accessible to anyone who is enrolled in the class.  Here is my proposed plan of action:   Ask the professor - in private - to post the grades using the online management system the professor already uses for other things.  If the professor doesn't fix this privacy violation, inform the professor that the method by which he/she post grades is a violation of federal law. As a last resort, contact the department dean. How does the color of a car influence its inner temperature change over time when parked outside in windless, hot and sunny regions?  I know what's the common idea about that: black cars are supposed to build up high temperatures faster because black objects absorb radiations instead of reflecting them off. Is it true? And then, what happens during the steady state? Some claim the black car will stay hotter, some others claim it will be the same whatever the color. Do all cars have the same temperature inside in the long run, or are some of them hotter?  I've Googled it but the best I could find was . It claims to be based upon ~20 articles. But there's not even a mention of absorption or emission spectrums. A priori, a black car could absorb all visible radiations and emit it as infrared while reflecting all of the Sun's infrared. And it's still only qualitative. I've found nothing on Physics stackexchange, the closest being .