How to strsplit data frame column and replicate rows accordingly?
Split comma-separated strings in a column into separate rows
$X/{\sim}$ is Hausdorff if and only if $\sim$ is closed in $X \times X$ How to set custom keyboard shortcuts from terminal? Efficiently replace all accented characters in a string? For a poor man's implementation of near-collation-correct sorting on the client side I need a JavaScript function that does efficient single character replacement in a string. Here is what I mean (note that this applies to German text, other languages sort differently):  native sorting gets it wrong: a b c o u z ä ö ü collation-correct would be:   a ä b c o ö u ü z  Basically, I need all occurrences of &quot;ä&quot; of a given string replaced with &quot;a&quot; (and so on). This way the result of native sorting would be very close to what a user would expect (or what a database would return). Other languages have facilities to do just that: , in , , . But what about JavaScript? Here is what I have right now. // s would be a rather short string (something like  // 200 characters at max, most of the time much less) function makeSortString(s) {   var translate = {     &quot;ä&quot;: &quot;a&quot;, &quot;ö&quot;: &quot;o&quot;, &quot;ü&quot;: &quot;u&quot;,     &quot;Ä&quot;: &quot;A&quot;, &quot;Ö&quot;: &quot;O&quot;, &quot;Ü&quot;: &quot;U&quot;   // probably more to come   };   var translate_re = /[öäüÖÄÜ]/g;   return ( s.replace(translate_re, function(match) {      return translate[match];    }) ); }  For starters, I don't like the fact that the regex is rebuilt every time I call the function. I guess a closure can help in this regard, but I don't seem to get the hang of it for some reason. Can someone think of something more efficient?  Answers below fall in two categories:  String replacement functions of varying degrees of completeness and efficiency (what I was originally asking about) A  of  , which is now  among JS engines (not so much at the time of the question) and could solve this category of problem much more elegantly. Kernel Panic - not syncing: VFS: Unable to mount root fs on unknown-block(0,0) The number of (non-equal) forests on the vertex set V = {1, 2, ...,n} that contains exactly 2 connected components is given by The number of (non-equal) forests on the vertex set V = {1, 2, ...,n} that contains exactly 2 connected components is given by $\sum_{k=1}^{n-1} {n-1 \choose k-1} k^{k-2} (n-k)^{n-k-2}$.  I am unsure how to approach this question. Could someone guide me through the proof? If G is a spanning tree and it is disconnected then I know it is a spanning forest. Also, I know by Cayley's thm that there are $n^{n-2}$ nonequal tree on a vertex set V = {1, 2, ...,n} which is where i'm assuming the $k^{k-2}$ comes from but I do not understand where the rest of it is coming from. You require a reputation of 50 to leave comments on others' questions/answers; the FAQ simply states this as a fact but does not explain it. I'm a new user and I have identified this as an issue very quickly through my own experiences so far. Looking at other questions seems to also provide justification against this 50 reputation requirement for comments on others' questions/answers.      In my own experience, I've seen a few questions like "how do I do x?" then the same poster has answered with "in the end I did it like this: ..." where their solution was perfectly sensible, but there may be some gotchas to watch for - in this case I want to vote up their answer and/or comment on it to point out the potential gotchas, but I can do neither!  To me all of the above seems justification against this rep requirement to comment, so what is the counter-argument and justification for it? In cricket how does someone become an umpire at international level? Is there some procedure for this? How are they selected and what is the criteria for this? What is the current state of apple device (iPhone, iPod, etc.) support? What ubuntu applications provide support? (guides, how to's, status) Also, specifically, details on support for syncing music to iPhone's and iPod's with the latest OS version:   Can you sync music to apple devices using >iOS4? (iPhone &amp; iPod) What applications allow you to do this and how? (guides, how to's, status)    What has already been established is:   Apple does not support Linux and has no plans to.  provides some support, however it currently does not support music/video synchronization with devices &gt;iOS4. Go to  and scroll to the section titled "" to see if your device version is supported. This is the profile of the object I'd like to wrap...    Here is the object's profile after being wrapped...    Is it possible to prevent the distortion? The following post here:  did not affect my object. It seemed very promising, maybe I'm missing something?  Note: I have applied the scale to both my object and curve. Are Constitution changes retroactive when calculating max HP? Lets say I'm a fighter that just leveled up to level 4, and decide to bring my Constitution up from 16 to 18. How many hit points do I have?  Level 1 = 10 (base) + 3 (Con mod) = 13.  Level 2 = 10 + 6 (average HP per fighter level) + 3 (Con mod) x 2 = 22  Level 3 = 10 + 6 (average) x 2 + 3 (Con mod) x 3 = 31  Level 4 = 10 + 6 (avg) x 3 + 3 (Con mod) x 3 (3 level-ups) + 4 (increased Con mod, which is now 4) x 1 = 41?  OR  Level 4 = 10 + 6 (avg) x 3 + 4 x 4 (4 times current Con mod) = 44?  If it's the first option, it's simply better to level Constitution up at earlier levels. Changing precision on a column in the attribute table without losing data? I have data in an Excel file that I want to join with a shapefile in my project. The Excel file contains values like volumes. The Excel file and the shapefile I want to join it with both contain the same property names.  The problem is, when I join the two, I get too many decimals in the attribute table. I get six, but I only want it to be one.  I tested to change the format of the cells to one decimal, and then I saved the file as *csv. But, somehow I seem to loose data in the process? It should be 42 rows that contains data in the column i am working with, but I end up with only like 10?  Another thing is that my property names contains the letters Å. Ä and Ö, perhaps this complicates things?  I read the question , but it doesn't mention the problem with the data loss.  My question was tagged with , but I didn't write what version I'm using. I use QGIS 2.2.0. Would it help to upgrade to the latest version? With the listings package, I would like to color the integers out of strings and comments and out of keywords too. The question for coloring numbers     . Some answer handle the numbers occurring within comments, strings or barewords, but no solution given work when a keyword contain a number. Which is annoying because C and C++ have a lot of types with a number in them, like uint32_t.  Here is a small example.  \documentclass{standalone} \usepackage{xcolor} \usepackage{listings}  \definecolor{darkgreen}{rgb}{0.18,0.54,0.34} \definecolor{maroon}{rgb}{0.64,0.16,0.16} \definecolor{darkpink}{rgb}{0.75,0.25,0.5}  \lstdefinestyle{myc++}{     language=[ISO]C++,     keywordstyle=\color{darkgreen}\bfseries,     commentstyle=\color{blue}\textit,     stringstyle=\color{darkpink}\ttfamily, %     literate=*     {0}{{{\textcolor{red}0}}}1     {1}{{{\textcolor{red}1}}}1     {2}{{{\textcolor{red}2}}}1     {3}{{{\textcolor{red}3}}}1     {4}{{{\textcolor{red}4}}}1     {5}{{{\textcolor{red}5}}}1     {6}{{{\textcolor{red}6}}}1     {7}{{{\textcolor{red}7}}}1     {8}{{{\textcolor{red}8}}}1     {9}{{{\textcolor{red}9}}}1,     escapeinside={|}{|}, %     morekeywords={int32_t} }  \begin{document}  \begin{lstlisting}[style=myc++] // In comment: 42 int32_t in_keyword = 80085; char *in_identifier|2| = "And in string 1337\n"; \end{lstlisting}  \end{document}   And the result:    The star for literate avoid to coloring the digits inside comments or strings. The escapeinside avoid coloring the digits inside a bareword when specifically marked. But I have yet to find how to color int32_t as a keyword. How do I switch to first person? Why does Maximum Likelihood estimation maximize probability density instead of probability I am trying to understand Maximum likelihood estimation but it looks like I am missing something rather elementary.          suppose we have an iid random sample $X_1, X_2,..., X_n$ for which the probability density function of each $X_i$ is $f(x_i; \theta)$ where $\theta$ is an unknown parameter. Then, the joint probability density function of $X_1, X_2,..., X_n$ is given by:          $f(X_1=x_1,X_2=x_2,\cdots,X_n=x_n)=\prod_{i=1}^{n} f(x_i, \theta)$      In Maximum Likelihood estimation, we try to maximize $f$ as a function of $\theta$.  Question: Why do we maximize probability density instead of probability? In what way does it make sense?  Edit: As explained in the answers, the probability of choosing a finite number of sample points from a continuous probability distribution is zero, so maximizing probability doesn't make sense, but how does maximizing probability density make sense? What is the real answer to the Birthday question? "How large must a class be to make the probability of finding two people with the same birthday at least 50%?"  I have 360 friends on facebook, and, as expected, the distribution of their birthdays is not uniform at all.  I have one day with that has 9 friends with the same birthday. (9 months after big holidays and valentines day seem to be big ones, lol..)  So, given that some days are more likely for a birthday, I'm assuming the number of 23 is an upperbound.  Has there been a better estimate to this problem? I would like to create a batch file, that will add registry key, not manually, but full automaticly by .BAT file.  goes about adding everything but not the key.  shows how to add everything, and how to add key manually, but it requires user interference, which I am trying to avoid.  Is there possibility to add KEY (non REG_*) to "folder?" in registry by one simple batch file? How do wizards cast spells which appear on their spell list when it has a divine focus component? What does a wizard do to cast a spell which contains a DF component? Take  for example,  Components V, S, DF    A divine focus component is an item of spiritual significance. The divine focus for a cleric or a paladin is a holy symbol appropriate to the character's faith. The divine focus for a druid or a ranger is a sprig of holly, or some other sacred plant. If the Components line includes F/DF or M/DF, the arcane version of the spell has a focus component or a material component (the abbreviation before the slash) and the divine version has a divine focus component (the abbreviation after the slash).  So do wizards have holy/unholy symbols in their spell components pouch or what? How do I write an Apex unit test? This is a canonical question and answer developed by the community to help address common questions. If you've been directed here, or your question has been closed as a duplicate, please look through the resources here and use them to shape more specific questions. To browse all canonical questions and answers, including more unit test resources, navigate to the  tag.  This canonical question is intended to address several classes of common questions by providing a quick summary and links to comprehensive resources:   How do I start writing my first unit test?  How do I unit test this code?  I need help writing this unit test.   Salesforce Stack Exchange looks for detailed, specific questions that the community can help you with, and can't write tests on your behalf. We feel that working with the resources below can help you get started, and we encourage you to make an attempt to write your test and return to SFSE with your specific questions when you encounter challenges you can't resolve. How to set the fully qualified hostname on CentOS 7.0? How do I set the fully qualified hostname on CentOS 7.0?  I have seen a few posts online for example using:  $ sudo hostnamectl set-hostname nodename.domainname   However, running domainname returns nothing:  $ domainname (none)   Also:  $ hostname nodename.domainname   However,  $ hostname -f hostname: Name or service not known $ hostname -d hostname: Name or service not known   Some debug output:  $ cat /etc/hostname nodename.domainname  $ grep ^hosts /etc/nsswitch.conf hosts:      files dns Is it possible to plot a graph of any shape? In school, I have learnt to plot simple graphs such as $y=x^2$ followed by $y=x^3$.  A grade or two later, I learnt to plot other interesting graphs such as $y=1/x$, $y=\ln x$, $y=e^x$. I have also recently learnt about trigonometric graphs and circle equations. In the internet, I have seen users posting graphs of different shapes like a heart-shaped graph and a Batman logo-shaped graph. I am sure there are numerous more graphs that I have yet to see. Seeing that the graphs can be shaped into shapes like the Batman logo and a heart brings me to my question: Is it possible to plot a graph of any shape regardless of its complexity? Perhaps, shaped into an outline of a person or a landmark? Why or why not?