Here is my code, i cannot figure out the difference between these two lists of list:   cow = 1 column = 1 size = 3 board1=[[0,0,0],[0,0,0],[0,0,0]] print board1 board2=[[0] * size] * size print board2  if board1==board2: print 'same'  board1[cow][column] =1 board2[1][2] =1 print "Board 1 is :", board1 print "Board 2 is :", board2   Result:  [[0, 0, 0], [0, 0, 0], [0, 0, 0]] [[0, 0, 0], [0, 0, 0], [0, 0, 0]] same Board 1 is : [[0, 0, 0], [0, 1, 0], [0, 0, 0]] Board 2 is : [[0, 1, 0], [0, 1, 0], [0, 1, 0]]
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?
What is the meaning of $\exp(\,\cdot\,)$? What is the meaning of the notation $\exp(\text{expression})$ ?  I think that it's something of the form $a^\text{expression}$ but does it mean that the base $a=e$ or can it be any base? Everything was working fine for a long time. But suddenly the device is getting slower than usual (e.g. apps react slowly when starting an action -- like the RSS reader takes "ages" to open an article). Also, several apps start crashing: force-closes as well as unexpected restarts. Sometimes this even involves some automatic reboot of the device.  Is there anything I can do, besides doing a factory-reset? Preferably it should work on un-rooted devices.  Remark: not all described problems may occur together, so on one device e.g. there might be no automatic reboot involved. Question remains the same, nonetheless. Profile Bug - Reputation Summary Not Displaying All Lines What is Active Directory Domain Services and how does it work? This is a  about Active Directory Domain Services (AD DS).         I find myself explaining some of what I assume is common knowledge about it almost daily. This question will, hopefully, serve as a canonical question and answer for most basic Active Directory questions. If you feel that you can improve the answer to this question, please edit away. Using article "the" with famous places? I'm editing a children's book about wonders of the World. In this book, the authors are not native speakers(they are XACT BOOK(India)), and they wrote these specific places without article "the":     -It is Taj Mahal.      -It is Tower of Pisa.   At first, I thought it's okay, but there are some pages has article "the":     -It is the Great Pyramid of Giza.      -It is the Temple of Artemis.   These sentences really make me confused. After researching, this website- - gives me some advice:     Do use the before:           names of rivers, oceans, and seas: the Nile, the Pacific          points on the globe: the Equator, the North Pole          geographical areas: the Middle East, the West     deserts, forests, gulfs, and peninsulas: the Sahara, the Persian Gulf, the Black Forest, the Iberian Peninsula      Unfortunately, I'm still not sure that adding "the" before each wonder's name is a right choice. Should I add article "the" or not? I already posted this problem in , but I'm still in vain. What happens if I activate a product key on Steam for a game I already own? I have a Steam product key for Just Cause 2 I got for free with the purchase of my video card. However, I already have a copy of this game attached to my Steam account. What will happen if I try to activate this other key on my account? Will Steam give me a copy of Just Cause 2 to gift to somebody else? Will it simply refuse to add it? Or will it eat the key rendering it worthless?  I don't want to try this only to have the latter happen, but it would be useful to be able to add it and gift it to somebody else. Proof that every number ≥ $8$ can be represented by a sum of fives and threes. Why is HMAC-SHA1 still considered secure? Openlayers v4.0.1 support Google Maps Javascript API? I want to know if the latest version of Openlayers (v4.0.1) supports Google Maps as a Tile Layer. I can't find any document ion about this. If Openlayers doesn't support Google Maps, could someone  tell me if there is any way to do this? Nice proofs of $\zeta(4) = \frac{\pi^4}{90}$? accessing loop variable within a loop Why does this not work with an imaginary exponent? Could someone please tell me why this exponentiation rule does not work when the exponent is imaginary?  The following seems to be true but is only true if $x$ is an integer.  $$e^{2\pi ix} = \left( e^{2\pi i} \right)^x = 1^x = 1$$ Issue with 'StringVar' in Python Program I am trying to create Thiessen (Voronoi) polygons, based on points within a defined shapefile extent. The output should be inclusive to the feature.  The output I receive now is the rectangular area around the selected points.    Steps I am using: 1. select points of interest (inside and outside spatial extent) 2. set primary display field to FID (aka:ObjectID) 3. Environment… > Set 'Analysis Mask' to shapefile with feature (in this case, a watershed)  Now here is where the problem starts. I have a set of instructions for arc 9.3, but I am now operating on ArcGIS 10 (Spatial Analyst installed &amp; activated). Also, just to clarify, I did scour the inter-webs for some number of hours- Esri support, gis.SE, Professor Google...  ########  9.3.1 version: Spatial Analyst >> Distance >> Allocation - set 'Assign To' as point shapefile of selected data - set cell size  10.0 methods tried: Analysis >> Create Thiessen Polygons -- Many variations of selected features -- File locations, both inside and out of file geodatabase  I am open to any solution, using Arc 10.0 and/or python would be ideal.  The first image is an example.  The output does not need to be exact.  wiki: In mathematics, we like talking about idempotent matrices. In a masters program that I am currently enrolled in, I have heard one professor pronounce it one way, and another professor pronounce it another way. The  explains it better than I could:  Is there a correct pronunciation for idempotent? Is it like omnipotent (om-nip-o-tent), so id-EMP-o-tent, or is it more like the two seperate words idem + potent I'd say EYE-dm-POT-nt, but then I speak Brit. Charles Matthews 07:57, 30 Jun 2004 (UTC) Ditto, but then I speak Australian ;) Dysprosia 08:01, 30 Jun 2004 (UTC) Actually the British is more like EYE-dm-PO-tnt, I guess. Charles Matthews I'd just like to pedantically point out that it would be pronounced i-DEM-po-tent because because syllable onsets are maximized. daesotho 20:33, 21 Oct 2004 (UTC) The American pronunciation puts primary stress on the second syllable ('dem') and secondary stress on the fourth syllable ('tence'). Could somebody more familiar with IPA than I am please add this to the article as an accepted pronunciation? My American dictionary says |ˈīdemˌpōtənt| for the adjective. I speak American (non-natively) and I wouldn't stress the second syllable for itempotence. My only question is, right now it says /ˌaɪdɪmˈpoʊtəns/ -- but can't it be stressed on the first syllable too? Should we add /'aɪdɪmˌpoʊtəns/ as an alternative? -- 87.160.141.177 (talk) 14:50, 3 June 2011 (UTC) And by the way I think it's silly giving a pronounciation guide as this is just imposing a particular accent. (For what it's worth I pronounce idempotent with a short 'i', as in the word 'id'). Alex Selby I agree with Alex Selby - the pronunciation guide should be extended to show the variation, or removed. Strictly, there's no reason for the first i to be long (neuter idem has a short first syllable in Latin), and I can't find any authoritative source which advocates the pronunciation given. Ms7821 (talk) 22:59, 15 July 2015 (UTC)  Is there a &quot;correct&quot; pronunciation for this word? Getting text from the Resource file in asp.net 4 Checking out  and  (and some papers) was a bit difficult for understanding Group Action. The closest to understanding was this part:    I understand the definition of homomorphism (a structure-preserving map between two algebraic structures of the same type). And from what I understand the symmetric group is a group of functions (bijective functions) mapping elements of a set $X$ onto itself.  However I get confused at this line:     ...an action of $G$ on $X$ may be formally defined as a group homomorphism $\phi$ from $G$ to the symmetric group of $X$.   That seems to be the definition of group action, but I am having trouble understanding how to apply that.  What that says to me is it is a homomorphism (function) $f \colon X \rightarrow S$ where $S$ is a set of bijective functions on $X$. That itself seems weird, I thought a group action would result in a number or something related to $\{1, 2, 3\}$ (defined next).  Continuing, if we have a set $X = \{1, 2, 3\}$ and a group $(*,\{4, 5, 6\})$, then the symmetric group of $X$ would be something like $S = \{1 \rightarrow 2, 2 \rightarrow 3, \dots \}$, and $\phi$ would be something like $f : \{4, 5, 6\} \rightarrow S$. That doesn't make sense to me and I feel like I'm interpreting something wrong. I don't see how mapping to a set of functions $S$ will result in an action on the set. Singular verb after two noun phrases joined by "and" that can be thought of as a single thing For linear regression, we can check the diagnostic plots (residuals plots, Normal QQ plots, etc) to check if the assumptions of linear regression are violated.  For logistic regression, I am having trouble finding resources that explain how to diagnose the logistic regression model fit. Digging up some course notes for GLM, it simply states that checking the residuals is not helpful for performing diagnosis for a logistic regression fit.  Looking around the internet, there also seems to be various "diagnosis" procedures, such as checking the model deviance and performing chi-squared tests, but other sources state that this is inappropriate, and that you should perform a Hosmer-Lemeshow goodness of fit test. Then I find other sources that state that this test may be highly dependent on the actual groupings and cut-off values (may not be reliable).  So how should one diagnose the logistic regression fit? How to find the matrix of a quadratic form? I was wondering. If I have a bilinear symmetric form, it is easy to find its matrix. But, when I have a quadratic form, which is the procedure to do that?  I heard that one possibility is: If $q$ is my quadratic form, then $$f(x,y) = \frac{1}{4}q(x+y) - \frac{1}{4}q(x-y)$$ is the bilinear symmetric form associated, so the method reduces to find the matrix of $f(x,y).$   The point is that seems a little noising... How to find, in practice, the matrix of quadratic form?  Thanks in advance.