I have a Python list of tuples:  vals = [(40.69, array([1.34, 1.516, 0.000135,....])), (213.69, array([0.34, 1.51256, 0.0110135,....])...] vals.sort()   The first element in the tuple is a float and the second element is a numpy ndarray. There are 784 elements in the array.   I get ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() at vals.sort. I am trying to sort on the first element in the tuple itself. This code works when I use a smaller dataset that produces only 13 elements in the ndarray. I can't figure out why it should throw this particular error if the number of elements is more.  Can anyone please help me out?
I've got a list of Python objects that I'd like to sort by an attribute of the objects themselves.  The list looks like:  &gt;&gt;&gt; ut [&lt;Tag: 128&gt;, &lt;Tag: 2008&gt;, &lt;Tag: &lt;&gt;, &lt;Tag: actionscript&gt;, &lt;Tag: addresses&gt;,  &lt;Tag: aes&gt;, &lt;Tag: ajax&gt; ...]   Each object has a count:  &gt;&gt;&gt; ut[1].count 1L   I need to sort the list by number of counts descending.  I've seen several methods for this, but I'm looking for best practice in Python.
I have an object at a fixed position in 3D space. I would like the camera to circle around it while facing it. I want to path of the camera to be circular in 2D, meaning that it does not move up or down.  I need this to be pretty accurate. I don't want to manually set a keyframe every frame for position and rotation. I would like to do this maybe with an expression, not with manual keyframing. I am not sure how to go about this but I think it is going to involve Python as well as some trigonometry. Why do corticosteroids harm COVID-19 patients? states that steroids could do more harm than good in treating coronavirus (COVID-19), referring to .      Understanding the evidence for harm or benefit from corticosteroids in   2019-nCoV is of immediate clinical importance.   It's unclear to me how exactly the use of corticosteroids (which is a common treatments for Asthma patients) can do harm other than the vague explanation of "steroids also impair the immune system's ability to fight viruses".   How exactly does the use of steroids harm the body in case of fighting a virus such as SARS-CoV-2 (2019-nCoV) that causes COVID-19? How to access a SQL Server database from other computer connected to the same workgroup? Could not open file archive.ubuntu.com_ubuntu_dists_eoan-updates_restricted_cnf_Commands-amd64.xz Greetings from Bangladesh. I am an intermediate user of Ubuntu OS. I am facing problem with apt update. I have searched online but could not find any answer to my problem so I am posting this question please help me.  Err:20 http://archive.ubuntu.com/ubuntu eoan-updates/restricted amd64 c-n-f Metadata   Could not open file /var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_eoan-updates_restricted_cnf_Commands-amd64.xz - open (13: Permission denied) [IP: 91.189.88.152 80] Ign:35 http://archive.ubuntu.com/ubuntu eoan-updates/multiverse amd64 c-n-f Metadata Err:37 http://archive.ubuntu.com/ubuntu eoan-backports/main amd64 c-n-f Metadata   Could not open file /var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_eoan-backports_main_cnf_Commands-amd64.xz - open (13: Permission denied) [IP: 91.189.88.152 80]   Reading package lists... Done E: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/eoan-updates/restricted/cnf/Commands-amd64  Could not open file /var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_eoan-updates_restricted_cnf_Commands-amd64.xz - open (13: Permission denied) [IP: 91.189.88.152 80] E: Failed to fetch http://archive.ubuntu.com/ubuntu/dists/eoan-backports/main/cnf/Commands-amd64  Could not open file /var/lib/apt/lists/partial/archive.ubuntu.com_ubuntu_dists_eoan-backports_main_cnf_Commands-amd64.xz - open (13: Permission denied) [IP: 91.189.88.152 80] E: Some index files failed to download. They have been ignored, or old ones used instead.   I have tried with         removing partial folder's content completely.   Cleaning apt by sudo apt clean   moving the lists to lists.old   then updating the apt      But without luck. How to reconcile the cashless human/Federation society with human traders and merchants From a variety of sources, including , we know that the Federation (or at least the humans) don't use money. This raises the problem that humans frequently visit worlds where there is currency, and, in the case of DS9, operate a station that has currency frequently in use (for example, Federation personnel frequently attend Quark's bar). Additionally, we see human traders.   My question is, how do humans get "money" (credits, latinum, etc.)? How would a human even get the resources to purchase their own merchant ship or the resources to fill its cargo holds with merchandise? If Federation personnel can simply be given money for the asking, why haven't they poured so much money down Quark's throat that he chokes on it? Tutorial on how to back up my full Ubuntu desktop and files? I would like to be able to back up all my settings and files to a dedicated external hard drive in a way that makes (1) all the backup files accessible and (2) would allow me to restore my system is there is a crash.   Is there an app for this or any pointers?  Thank so much. Now, I know that it's (relatively) easy to calculate, say, $r^{a+bi}$ (using the fact that, for  $z_1, z_2\in \mathbb{C}, {z_1}^{z_2}=e^{z_2\ln(z_1)}$ and $\ln(z_1$) can just be found using: $\ln(a+bi)=\ln[\sqrt{a^2+b^2}]+i \cdot \arctan(\frac{b}{a})$  ).  Anyway, how would I go about calculating, say, $i^j, k^i$ etc., or, more generally, $(a_1+b_1i+c_1j+d_1k)^{a_2+b_2i+c_2j+d_2k}$  (I know that exponentiating a complex number (to another non-real complex number) produces a non-unique result, so I assume the same would apply further up the hypercomplex ladder; if that's the case, I'm only concerned with the 'principal' value)?  I obviously don't want a general formula or anything like that; just some intuition and a method by which I could calculate such a thing.  And, finally (because I really like to push my luck), can this method for quaternions be extended to higher number systems (i.e. $\mathbb{O, S},$ etc.) to give an analogous result?   Thanks How do I remotely wake my Mac over Wi-Fi? How do I escape a backtick ` within in-line code in Markdown? Physics are not simulated past a certain frame? I've set up the physics of a swinging wrecking ball and set the animation to run for 240 frames.  This was not long enough for the entire "swing" of the ball-and-chain.   I'm unable to reset the timeline, but I can set the end frame to (say) 1000 frames, but when I try to play the animation, the animation progress halts at frame 240 and I cannot get it to go any further.   There are no markers or keyframes in the timeline.  What should I do to "force reset" the animation-timeline, to allow changes to the length? Showing $\sum_{i = 1}^n\frac1{i(i+1)} = 1-\frac1{n+1}$ without induction? I oversaw a high-school mathematics test the other day, and one of the problems was the following     Show, using induction or other means, that $$\sum_{i = 1}^n\frac1{i(i+1)} = 1-\frac1{n+1}$$   The induction proof is very standard, where the induction step relies on the fact that $\frac{1}{n+1} + \frac{1}{n(n+1)} = \frac{1}{n}$, and I'm sure it's been answered on this site before. However, I got intrigued by the "or other means" part of the question.  I don't know whether the teacher who wrote the test even considered any alternative solutions (he may just have written it so that if anyone has a crazy idea that works out, then they should get a full score for it), but I tried to find one. For instance, we may do the following telescope-ish argument: $$ \frac{1}{1(1+1)} + \frac{1}{2(2+1)} + \cdots + \frac{1}{(n-1)n} + \frac{1}{n(n+1)} + \frac{1}{n+1}\\ = \frac{1}{1(1+1)} + \frac{1}{2(2+1)} + \cdots + \frac{1}{(n-1)n} + \frac1n\\ \vdots\\ = \frac{1}{1(1+1)} + \frac12\\ = 1 $$ However, I feel that this is just an induction proof in disguise (hidden in the vertical dots). If one uses the mechanics of the induction proof to check whether the formula is true for a specific $n$, then one certainly does the exact same calculations as I have done here.  Is there a proof of this fact that clearly does not use induction (or at least hides it better)? The more elementary the better, and the ultimate goal would be to do it within the syllabus of the students taking the test (or at least not far from it). For reference, they should be familiar with the summation formula of arithmetic and geometric series and their derivations (so techniques resembling those would be well within specifications).  If there is a solution using calculus, then the students should be able to integrate elementary trigonometric functions, as well as exponential functions, logarithms and rational functions. They are familiar with integration by parts, substitution and partial fractions.  I welcome more advanced solutions as well, of course. I have two different machines (home and work) running Ubuntu 18.04. Last night vim froze at home. I was in insert mode and typing and went to save (esc :w) and nothing happened. The status bar still reads -- INSERT --, the cursor is still blinking where it was. I was stuck. I couldn't find a way out. I couldn't type (nothing happened when I type), I couldn't move around (the up and down arrows did nothing). It was stuck in insert mode with the cursor blinking where it was.   I was definitely multitasking and probably hit some other keys in there, but I don't know what keys. It was late, though, so I closed the terminal window and tried again (I was entering a git commit message). It happened again partway through my typing so I switched to git commit -m "don't need an editor for this" instead. And then I shut down my computer and stopped working.  I figured I was just tired, but then it happened to me today at work on a different laptop altogether. Again I was multitasking and can't swear I didn't type any bizarro key sequence but if I did it was accidental. And other tabs in the same terminal aren't frozen.   I'm used to getting trapped in visual mode in vim. That's a trick I've learned. But stuck in insert mode? Any ideas on what I might've done and how to get out of it?   Per a comment suggestion I tried looking at .viminfo but the only .viminfo I see is owned exclusively by root and only appears to show things I would have edited with sudo:   # Input Line History (newest to oldest):  # Debug Line History (newest to oldest):  # Registers:  # File marks: '0  1  0  /etc/neomuttrc |4,48,1,0,1531789956,"/etc/neomuttrc" '1  1  66  /etc/apt/sources.list.d/signal-bionic.list |4,49,1,66,1530816565,"/etc/apt/sources.list.d/signal-bionic.list" '2  51  0  /etc/apt/sources.list |4,50,51,0,1530816531,"/etc/apt/sources.list"  # Jumplist (newest first): -'  1  0  /etc/neomuttrc |4,39,1,0,1531789956,"/etc/neomuttrc" -'  1  66  /etc/apt/sources.list.d/signal-bionic.list |4,39,1,66,1530816565,"/etc/apt/sources.list.d/signal-bionic.list" -'  1  66  /etc/apt/sources.list.d/signal-bionic.list |4,39,1,66,1530816565,"/etc/apt/sources.list.d/signal-bionic.list" -'  51  0  /etc/apt/sources.list |4,39,51,0,1530816531,"/etc/apt/sources.list" -'  51  0  /etc/apt/sources.list |4,39,51,0,1530816531,"/etc/apt/sources.list" -'  51  0  /etc/apt/sources.list |4,39,51,0,1530816531,"/etc/apt/sources.list" -'  51  0  /etc/apt/sources.list |4,39,51,0,1530816531,"/etc/apt/sources.list" -'  1  0  /etc/apt/sources.list |4,39,1,0,1530816447,"/etc/apt/sources.list" -'  1  0  /etc/apt/sources.list |4,39,1,0,1530816447,"/etc/apt/sources.list" -'  1  0  /etc/apt/sources.list |4,39,1,0,1530816447,"/etc/apt/sources.list" -'  1  0  /etc/apt/sources.list |4,39,1,0,1530816447,"/etc/apt/sources.list"  # History of marks within files (newest to oldest):  &gt; /etc/neomuttrc     *   1531789952  0     "   1   0  &gt; /etc/apt/sources.list.d/signal-bionic.list     *   1530816564  0     "   1   66     ^   1   67     .   1   66     +   1   66  &gt; /etc/apt/sources.list     *   1530816454  0     "   51  0   It seems odd that I wouldn't have an unprivileged .viminfo but I did sudo udpatedb and locate .viminfo and still didn't surface more than the one root-owned file. How can I make a bootable, unattended USB restore disk? I have a load of 14.04 kiosk systems, halfway across the country. These are horrible little integrated devices. I need to upgrade them all to 16.04 to support a new software stack. do-release-upgrade works half the time. The other half it destroys the install. In addition, the CPUs are really slow and  network connections at some sites are also pretty shoddy. So even when it works, upgrading takes a long time.  So new plan. I can make a fully-installed system image for each kiosk in Virtualbox, or LXC, or whatever. I need a way to get these images unpacked onto the systems.  The main problem here is there are very few technical people available at the other end. And I don't want to fly 200 miles to do this myself. I need something that is almost completely automated and doesn't require a keyboard.  I'm imagining a scenario where:   I make a system image for each kiosk I make a bootable USB drive for each kiosk and copy on the kiosk image. I label each and post them. At the other end, a staff member with physical access to the USB ports just plugs in the right drive and reboots. The bootable element of this then writes and expands the disk image.   It's that "bootable element" that I'm looking for. I was expecting that something like this might already exist (for bulk reimaging installations) but it's possible I'm in new territory. Anything that gets my images installed without manual interference (past plugging it in) gets points.  As far as I know, options like Clonezilla require somebody with a keyboard to tell it what to do. I need something that doesn't require a keyboard, just gets on and does it. I've been using the beta iCloud Photo Library for a week and a bunch of photos got duplicated and I'd like to wipe all the photos out and start over.  I have backups of all the photos and have turned off iPhoto Cloud Library on all iOS devices. When I log into the web app - it still shows dozens of albums and I can delete all the photos, then go to deleted items and then purge them, but the ghost albums are still there messing things up.  I've turned off the library entirely and you can see there is a 30 day waiting period.     If I click on albums, there are pages of them and no delete button anywhere. If I turn on the library on an iOS device, data starts flooding back as if I wanted to recover the photos.  I don't want to recover anything, I want a clean wipe and clean slate.  Currently, there are 7807 photos in the deleted album and no way to mass delete them. I have 31 albums that show up in iCloud and no way to delete them.  Is there some way to accelerate this or must people wait a month for a corrupt library to eventually be purged to start over?  (I have tickets open with AppleCare after  and it's escalated to engineering, but I was informed that it might be a week or two before it gets seen :-( Perhaps someone has a better idea to clear things out or noticed something I've missed.) Shine a light into a superconductor A type-I superconductor can expel almost all magnetic flux (below some critical value $H_c$) from its interior when superconducting. Light as we know is an electromagnetic wave. So what would happen if we shine a light deep into a type-I superconductor? Suppose the magnetic field of the light is significantly lower than $H_c$.  And what about type-II superconductors? JSF 2.1 ViewScopedBean @PreDestroy method is not called How can I execute a function on pressing the enter key in an  field? It's a standard result that given $X_1,\cdots ,X_n $ random sample from $N(\mu,\sigma^2)$, the random variable $$\frac{(n-1)S^2}{\sigma^2}$$ has a chi-square distribution with $(n-1)$ degrees of freedom, where $$S^2=\frac{1}{n-1}\sum^{n}_{i=1}(X_i-\bar{X})^2.$$ I would like help in proving the above result. Thanks. When to use \LetLtxMacro? Frequently I see users redefine macros using (for example)  \let\oldmacro\macro% Store \macro in \oldmacro \renewcommand{\macro}{%   % ...redefined \macro   \oldmacro% }   and other times they use  \usepackage{letltxmacro}% http://ctan.org/pkg/letltxmacro \LetLtxMacro{\oldmacro}{\macro}% Store \macro in \oldmacro \renewcommand{\macro}{%    % ...redefined \macro   \oldmacro% }   Why would one use \LetLtxMacro when \let works just as well? Or, more specifically, when would one use \LetLtxMacro and/or why? How can I get the values of the parameters of a calling method? Question  I'm writing some code that needs to be able to get the values of the parameters from the method that called into the class. I know how to get all the way to the ParameterInfo[] array, but I don't know how to then get the values. Is this even possible?  If it is, I think it has something to do with using the MethodBody property from the MethodInfo object, which allows you to inspect the IL stream, including properties, but I don't know how to do it, and I haven't found applicable code on Google.  Code  // Finds calling method from class that called into this one public class SomeClass {     public static void FindMethod()     {         for (int i = 1; i &lt; frameCount; i++)         {             var frame = new StackFrame(i);             var methodInfo = frame.GetMethod();             if (methodInfo.DeclaringType != this.GetType())             {                 string methodName = frame.GetMethod().Name;                 var paramInfos = methodInfo.GetParameters();                  // Now what?? How do I get the values from the paramInfos                  break;             }             else if (i == frameCount - 1)             {                 throw new TransportException("Couldn't find method name");             }         }     } }