how to get all possible solutions to delete duplicate items from a list (python)
How do you remove duplicates from a list whilst preserving order?
Use the new helpcenter for the question/answer ban message Related:    The helpcenter has . It still links to the  for further details. Besides that, the question ban message .  Now that we have the helpcenter, could the following changes be implemented?   Link to the help center instead of the meta post Remove the link to the meta post from the help center, and instead incorporate its contents into the helpcenter itself Centering polygon on specific coordinates using QGIS I need to place a set of polygons onto a set of points, so that each polygon is centered on its corresponding point. How do I do that? In MapInfo I can just manually edit the coordinates of the center, but there does not seem to be an equivalent in QGIS. The number of different ways to choose $k$ out of $n$ unique items The number of different ways to choose $k$ out of $n$ unique items:   Without repetition and without order-significance: $\binom{n}{k}=\frac{n!}{k!(n-k)!}$ Without repetition and with order-significance: $\binom{n}{k}\times k!=\frac{n!}{(n-k)!}$ With repetition and with order-significance: $n^k$ With repetition and without order-significance: $?$   Thank you! "It's time something was / were done about the problem." It's time something was done about the problem.   It is a sentence from Murphy's "Grammar". Using was confused me, for me it should be were. It looks like this clause is in subjunctive mood&mdash;something that is unreal / imaginary, and in that case you always use were for any object.  Unless, of course, it is not the subjunctive mood, what would knock me down. Isomorphism $H_n(D^n, S^{n - 1};A)$ and $A$ The homomorphism $a \mapsto [[a \cdot f]]$ is supposed to be an isomorphism between $A$ and $H_n(D^n, S^{n - 1};A)$ for any homeomorphism $f: \Delta^n \to D^n$. I have proven that it is well defined and injective, but why is it surjective?  The group $H_n(D^n, S^{n - 1};A)$ is generated by elements of the form $a \cdot \sigma + b \cdot \tau + c \cdot \partial(\kappa)$ where $\sigma: \Delta^n \to D^n$, $\tau: \Delta^n \to S^{n - 1}$ and $\kappa: \Delta^{n + 1} \to D^{n + 1}$ and I do not see how an element of this form represents the same equivalence class of $[[m \cdot f]]$ for some $m \in A$. We can write $\sigma$ as $f f^{-1} \sigma$ to get $f$ in there, but I don't see that working out. Any hints? Adding a text node to tikz drawing is $\sqrt{x}$ always positive? Changing top, bottom, left & right margins on the fly I’m trying to find a way of being able to modify all of the margins of a page whenever I want to and as many times as I want to on a single page in order to be able to put text very easily where I want on a page.   I have thought of using the geometry package and using   \newgeometry{left=6.75cm, right=1cm, top=1cm, bottom=1cm}  %…  \restoregeometry   but unfortunately this only works for whole pages, so I can only change the margins once per page (and then they are valid for the whole page without having the possibility of changing them again).   I found the following script on the internet which enables users to change margins on the fly, just as I want to. The code below works fine and enables me to change the left and right margins of my page as many times as I want to, but unfortunately, it doesn’t give me the option of changing the top and bottom margins.  % placed before \begin{document}  \newenvironment{changemargin}[2]{% \begin{list}{}{% \setlength{\leftmargin}{#1}% \setlength{\rightmargin}{#2}% }% \item[]} {\end{list}}  % And then inside the document, whenever I want to use % the command to change the margins on the current page  \begin{changemargin}{1.9875cm}{-3.7625cm} % this means the left margin increases by 1.9875cm compared % to the default left margin (4.7625cm) (so left margin=6.75cm here) % and the right margin decreases by 3.7625cm (so right margin=1cm)  % ... (text or pictures in new environment)  \end{changemargin}   For this reason, I tried to adapt the code above and came up with the code below:  % placed before \begin{document} \newenvironment{changemargin}[3]{% \begin{list}{}{% \setlength{\leftmargin}{#1}% \setlength{\rightmargin}{#2}% \setlength{\topmargin}{#3}% }% \item[]} {\end{list}}  % And then to use the command: \begin{changemargin}{1.9875cm}{-3.7625cm}{1cm} % ... \end{changemargin}   It compiles and still changes the left and right margins but the top margin remains unchanged. (I haven’t yet tried to change the bottom margin).  Can anyone help me get this code to work completely, and enable me to modify the left, right, top and bottom margins of a page? Thanks. What is the default root password? How Can I Concatenate Column A and Column B into Column C in Excel? Column A has first name.  Column B has last name.  I need column C to be "display name" (first name and last name separated by a space).  I assume this involves the concatenate function.  Bonus Question: Column D is email address.  I need column E to be "username" (everything in email address left of the @ symbol).  I assume this involves some regular expression function. What is the easiest way to make a backup of an entire hard disk I got myself a dell laptop from the local computer store. Its a used machine with Windows Vista Home Basic on it. I want to load Ubuntu Desktop 10.10 though so I can do perl development. BUT I want to keep a copy of the entire harddrive with the dell utility partition and Windows Vista in case I want to go back. I was thinking I could image the drive but I not sure what to use, I don't have Ghost or anything, Someone had told me about Clonezilla. Would that work for me? Is it hard to use? Also I want to burn the data to a DVD or something more storable than a harddisk. How do I change directory back to my original working directory with Python? Prove that the dihedral group $D_4$ can not be written as a direct product of two groups How to adopt SD card as internal storage on Samsung devices? What level is a spell if you cast it without expending a spell slot? Usually, when we see two letters put together it is to define the pronunciation or to differentiate synonyms or just its foreign origins. But some words don't seem to have any reason to double up.     Why does vacuum have two of the letter U?  Why does aardvark have two of the letter A?  Why does llama have two of the letter L? The suggested edits count at top is incorrect. Multiple browser refreshes did not clear it. Approving/Rejecting review decreases the count, but as you can see the count is incorrect. Read Gif Images using WebView android Do black holes have a moment of inertia? My question is in the title: Do black holes have a moment of inertia?  I would say that it is: $$I ~\propto~ M R_S^2,$$ where $R_S$ is the Schwarzschild radius, but I cannot find anything in the literature. init.m in Autoload directory is not read by parallel kernels in M11.2