I was experimenting with lists in python and found the following confusing.  &gt;&gt;&gt; a = [1, 2, 3, 4] &gt;&gt;&gt; A = [a]*3 &gt;&gt;&gt; A [[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]] &gt;&gt;&gt; a[2] = 45 &gt;&gt;&gt;  &gt;&gt;&gt; A [[1, 2, 45, 4], [1, 2, 45, 4], [1, 2, 45, 4]] &gt;&gt;&gt; A = a * 3 &gt;&gt;&gt; A [1, 2, 45, 4, 1, 2, 45, 4, 1, 2, 45, 4] &gt;&gt;&gt; a[2] = 3 &gt;&gt;&gt; A [1, 2, 45, 4, 1, 2, 45, 4, 1, 2, 45, 4]   First, I multiplied like this: A = [a]*3 and changed an element of a. A changed because it contained 3 references of a. Then, I multiplied like this: A = a*3 and changed the same element of a. Now, why did A not change, assuming that it contained 3 references of a, too?
I needed to create a list of lists in Python, so I typed the following: my_list = [[1] * 4] * 3  The list looked like this: [[1, 1, 1, 1], [1, 1, 1, 1], [1, 1, 1, 1]]    Then I changed one of the innermost values: my_list[0][0] = 5  Now my list looks like this: [[5, 1, 1, 1], [5, 1, 1, 1], [5, 1, 1, 1]]    which is not what I wanted or expected. Can someone please explain what's going on, and how to get around it?
Redirect all subsequent commands' stderr using exec I have this MySQL query:  SELECT DAYOFYEAR(`date`)  AS d, COUNT(*)  FROM  `orders`  WHERE  `hasPaid` &gt; 0 GROUP  BY d ORDER  BY d   Which returns something like this:  d  | COUNT(*) | 20 |  5       | 21 |  7       | 22 | 12       | 23 |  4       |   What I'd really like is another column on the end to show the running total:  d  | COUNT(*) | ??? | 20 |  5       |   5 | 21 |  7       |  12 | 22 | 12       |  24 | 23 |  4       |  28 |   Is this possible? How old is SpongeBob? I don't mean how old is the series, I mean what is SpongeBob's age if he were a real person. I ask because his age seems to be ambiguous in the show.   He has a full-time job He has his own house He is always referred to as a kid (especially in the movie) He acts childish and immature In one episode, he was pretending to be an adult/grown-up Clipping raster with mask in QGIS gives AAIGrid error? In popular science books and articles, I keep running into the claim that the total energy of the Universe is zero, "because the positive energy of matter is cancelled out by the negative energy of the gravitational field".  But I can't find anything concrete to substantiate this claim. As a first check, I did a calculation to compute the gravitational potential energy of a sphere of uniform density of radius $R$ using Newton's Laws and threw in $E=mc^2$ for energy of the sphere, and it was by no means obvious that the answer is zero!  So, my questions:   What is the basis for the claim &ndash; does one require General Relativity, or can one get it from Newtonian gravity? What conditions do you require in the model, in order for this to work? Could someone please refer me to a good paper about this? Is the ideal $I = \{f\mid f (0) = 0\}$ in the ring $C [0, 1]$ of all continuous real valued functions on $[0, 1]$ a maximal ideal? Is the ideal $I = \{f \mid f (0) = 0\}$ in the ring $C [0, 1]$ of all continuous real valued functions on the interval $[0, 1]$ a maximal ideal? In the sentence     What’s funny is Cat’s dry humour.   Wouldn’t it be better to put a comma after “funny”:     What’s funny, is Cat’s dry humour.   This question entails a (at the time of writing) heated discussion in the . How hard do early-career academics in the United States work, really? I'm finishing a PhD in Sweden this year and seeking a post-doc in the United States (atmospheric remote sensing).  It is clear that a job in academia is not a nine to five job; nor do I want it to be.  I often work late in the evening when I'm on a productive spur.  When an important dead-line is coming up, one needs to work harder, and there is no overtime paid.  I accept that.  However, no matter how much I'm interested in my research, I do enjoy and need a reasonable amount of spare time, too; relaxing on the weekends, occasionally a long weekend away, and sometimes a longer trip, such as three weeks in the wilderness.  Regarding the normal work ethos for early-career academics in the United States, I have a hard time judging what is normal and what is excessive.  Some examples:    warning post-docs that he expects all of the members of the group to work evenings and weekends. My apparent naïveté in believing that , despite Wikipedia  as a rest from work, or a hiatus, often lasting from two months to a year.  I was thinking of my friend, who spent a year between his PhD and his first post-doc travelling from France to Mongolia mostly on foot. Someone  I am not a good role model, but when I don't work on a Sunday, I count that as a vacation day.  having no employment-related benefits such as paid vacations, sick leave, or unemployment compensation. Question    We don't have such a work-ethos where I'm at.  I belief that working too hard risks stress and burn-out, and does not increase productivity in the long run, nor human well-being.  I want to do science.  Doing science makes me happy, but having time to relax while not doing science is important for me.  Does the selection of examples I gave above represent a normal situation in U.S. early-career academia?  Should I expect an attitude where asking for a 3-week holiday during the summer is considered as being not serious, or is the situation in practice usually not as bad as the examples above make it sound?  How hard to early-career academics in the United States work, really? 80's pop song with lyric "It's the story of my life if you wanna know" I'm trying to identify a song by a female 80's pop group.   Here are the lyrics I remember:     It's the story of my life if you want to know   a play where everything is meant to be   you're the story of my life and I can't let you go Make font size bigger than max limit of 1296 pt in Adobe Illustrator (2015)? For some reason and for many years there's a limit for font size in Illustrator. It is 1296 points max, so you can't go bigger without converting type to outlines first. Converting to outlines means you will not be able to edit type parameters and text it-self. Don't know how about you, but this makes me sad in non-destructive editing era.  What's your workaround? Wow, the iOS app feed sure showed me an interesting question! I want to read more. Uh, how do I get there? In the iOS app, pulling up a question from the feed gives the standard question view, which provides no means of navigating elsewhere on that site, either to browse or search. This should be changed for feed questions.  For example, I tapped on a highlighted Seasoned Advice question today, and found that I wanted to make a comment pointing to a related question on the site. The best way I could think of finding that post was to leave the app and use my browser. Then I came back with the link to copy-paste in.  Similarly, a question in the feed might be so intriguing that I want to look around for more cool stuff on the site. That requires two taps back and then a search via the "All Sites" menu item.  I'd suggest that questions selected from the feed should get a special header bar (or maybe stuck in between the questions and the answers) that provides a "More posts!" link at least to the site's top view; ideally there would also be a search field that could pop out of it.  Another possibility that would work pretty well, although it's a small tap target on a phone, would be to link the site name that appears under the question title to the site's top view. Does text in brackets invoke the "an" vs. "a" rule? I have a land cover classification derived from Landsat TM imagery - I created this classification using ENVI. I would like to edit individual and groups of cells in some areas of the classification in order to improve the accuracy of the output by comparing it with aerial imagery.  Is there a way, using ArcGIS Desktop, to manually edit large groups of cells by selecting them and assigning them to a new or existing class?   I am aware of merging methods based on class statistics, but the area I'm classifying has a high amount of spectral confusion due to thin cloud cover - it seems like a manual edit is the only way to go. I'm trying, but something is wrong with my code in LaTeX: \begin{asy} pair dynkinMark(real x, real y, string s = &quot;&quot;, pen p = defaultpen, pair B = dir(45)) { if (s != &quot;&quot;) { dot(&quot;$&quot;+s+&quot;$&quot;, (x,y), B, p); }     else { dot((x,y), p); }     return (x,y); }  dynkinMark(0,1, &quot;1&quot;, dir(135)); dynkinMark(0,2, &quot;2&quot;, dir(135)); dynkinMark(0,3, &quot;3&quot;, dir(135)); dynkinMark(0,4, &quot;4&quot;, dir(135)); dynkinMark(7,1, &quot;1'&quot;); dynkinMark(7,2, &quot;2'&quot;); dynkinMark(7,3, &quot;3'&quot;); dynkinMark(7,4, &quot;4'&quot;); path p1 = (0,1)..(2,2.0)..(5,3.5)..(7,4); path p2 = (0,2)..(2,1.2)..(5,2.5)..(7,3); path p3 = (0,3)..(2,2.8)..(5,1.5)..(7,1); path p4 = (0,4)..(2,3.8)..(5,3.5)..(7,2); draw(p1, blue); draw(p2, heavycyan); draw(p3, mediumcyan); draw(p4, lightblue); dot(&quot;$12$&quot;, IP(p1, p2), dir(90), heavygreen); dot(&quot;$13$&quot;, IP(p1, p3), dir(90), heavygreen); dot(&quot;$23$&quot;, IP(p2, p3), dir(90), heavygreen); dot(&quot;$14$&quot;, IP(p1, p4), dir(90), heavygreen); dot(&quot;$24$&quot;, IP(p2, p4), dir(90), heavygreen); real y = 0.8; label(&quot;$s_1$&quot;, (IP(p1,p2).x, y), heavygreen); label(&quot;$s_2$&quot;, (IP(p1,p3).x, y), heavygreen); label(&quot;$s_1$&quot;, (IP(p2,p3).x, y), heavygreen); label(&quot;$s_3$&quot;, (IP(p1,p4).x, y), heavygreen); label(&quot;$s_2$&quot;, (IP(p2,p4).x, y), heavygreen); \end{asy} This is not a duplicate of this .  The linked question says that it suffices to show that if $(x_n)\to x$ then $(\frac{x_1+\cdots+x_n}{n})\to x$ to prove my question, but how so? I tried using the same strategy as how one proves that if $(x_n)\to x$ then $(\frac{x_1+\cdots+x_n}{n})\to x$, by "splitting" the product in th $N$th term:  $$\sqrt[n]{x_1x_2\cdots x_n}=\sqrt[n]{x_1x_2\cdots x_Nx_{N+1}\cdots x_n}=\sqrt[n]{x_1x_2\cdots x_N} \sqrt[n]{x_{N+1}\cdots x_n}$$  but it seems I can't use for now the definition of convergence of $(x_n)$ because of the $n$th root. I also tried to use a result: if $(x_n)\to x$ then $(\frac{x_n}{n})\to 1$ but don't know if this is true. Sadly I've had no real progress. Any help will be greatly appreciated, thanks in advance! How to save animation as a video format I am basically trying to make an intro for my youtube channel. I am sort of familiar with the program because I was playing around with it for a long time, getting the basics of it. With the help of youtube videos I am basically done with my project. I put my name in it and everything. I just need to know how to save the animation onto my desktop as a file that I could open and would be in a video format. On what criteria should I evaluate domain registrars? Though I've been a web developer for a fair amount of time, I am going for the first time to buy a few domain names.  I have looked into the domains I'm going to buy and know that they're available, and I've been looking into which sellers to use.  After doing a lot of research, the main ones I'm considering are 1&amp;1, Namecheap, and Gandi.  The problem is, when continuing to research, I'm not really sure what makes one domain seller distinct from another.  I don't need much in the way of services--definitely not hosting, since I plan to use Heroku for that.  I mainly only need the domain itself and DNS management, as well as possibly SSL certificates and WHOIS protection.  Question:  What makes one domain seller different from another?  How can I go about evaluating which one is the best for me?  Note:  This question is not which domain seller is the best, but rather, what criteria can I use to evaluate them and rank one over another.  I'm trying to find out what makes one domain seller different from another, since they all seem to be pretty similar to me right now. Is it possible to interrupt spellcasting? Login not redirecting back to page where login link was clicked if account created I'm not too sure whether this is the right place to ask this (and please correct me if it is not), but I'm currently studying a course in Algebraic Number Theory and would like to be pointed in the direction of any solved problems that can assist in learning.  I have the book Problems in Algebraic Number Theory by Murty and Esmonde, which is particularly good, but are there any further sources (inc. online) available that do a similar job?   It is so often frustrating to be presented with an extensive list of practice questions, many of which form part of the exposition of the material (as in Number Fields by Marcus for example) and then to have no real way of knowing whether any solution you generate is correct and has not made any oversights.   MSE is undoubtedly a good place to verify any answers and clear up issues, but question limits and the impracticality of going online every time a solution seems suspect (or the question is computational and lacks any result to check against) form a barrier.  I suppose any ANT textbook that has an accompanying solutions manual or online published solutions is what I have in mind. Or failing that, links to institutions running a course in ANT with answers to homework exercises.  Thanks in advance.