I came across a meta-programming task that seemed like it must have an obvious and simple answer, but I could not find one.  I have a bunch of names wrapped in ():  (foo, bar, buzz, zap)   I want to quickly convert these names to a character vector:  ("foo", "bar", "buzz", "zap")   The fastest I could come up with is as follows:  as.character(quote(c(foo, bar, buzz, zap)))[-1] # "foo"  "bar"  "buzz" "zap"    I've got to imagine there's a cleaner solution.  EDIT  Possible duplicate, just with a very different title so it was hard to discover:
Anyone know if R has quote-like operators like Perl's qw() for generating character vectors?
in elisp's let, how do you reference a variable bound in the same let while binding another variable? What is the usage of Zero Ohm & MiliOhm Resistor? I am new to PCB design and I noticed that some schematics use 0Ω or 100mΩ resistors. What is their purpose and why do we need to use them in our PCB design?  Normally if we wish to probe how much current the load is taking, we put a jumper pin across the PCB trace (then measure current across the pin using a multimeter). Adding resistors for this purpose seems like it would waste a lot of PCB real-estate. Is this the sole reason why 100mΩ resistors are being placed (since I = V/0.1Ω) instead of a jumper pin?   If so, is there any consideration we should take when placing such a mΩ resistor on board so it doesn't affect the signal or behaviour of the circuit? Question: Let $E$ be a normed space. Let $G$ be a closed subspace of $E$ and let $F$ be a finite dimensional subspace of $E$. Show that $F+G$ is a subspace of $E$ and is closed.  I'm having trouble in showing $F+G$ to be closed. I know that $F$ is itself closed and complete, as it is a finite dimensional subspace of a normed space, and that if $F$ were compact that $G+F$ would be closed. I also know that the closed unit ball of any finite dimensional normed space is compact.  I tried two methods. One was to take a convergent sequence $(x_n)_{n \in \mathbb N}$ in $G+F$. Then we can write $x_n = f_n + g_n$ where $f_n$ and $g_n$ are sequences in $F$ and $G$ respectively, and I attempted to find a way to force the individual components $f_n$ and $g_n$ inside the unit ball which would enable me to say that they had convergent subsequences. I couldn't see how to do this, however.   The other thought was to try and show that $F$ is compact, but I don't see a way to do this as I can't imagine it to be simply true without some other conditions on $F$.  Are one of these methods the right way to go? Or should I go another direction? I would appreciate any help I can get, although I would prefer not to be presented with a full proof so that I can do some work for myself. Thanks! Why does k-means clustering algorithm use only Euclidean distance metric? Is there a specific purpose in terms of efficiency or functionality why the k-means algorithm does not use for example cosine (dis)similarity as a distance metric, but can only use the Euclidean norm? In general, will K-means method comply and be correct when other distances than Euclidean are considered or used?  [Addition by @ttnphns. The question is two-fold. "(Non)Euclidean distance" may concern distance between two data points or distance between a data point and a cluster centre. Both ways have been attempted to address in the answers so far.] How to install hp scanjet 200 in Ubuntu 12.04? Unable to scan with hp scan-jet 200. When I type lsusb command in terminal it shows the scanner details.  I opened the simple scan which displays no scanners found, and x sane image scanners also displays the same error. I have blender 2.69 and I've been following a tutorial on how to make text.  The only problem is when I go to add a glossy shader in the node editor it does not exist. Neither does the shader category. Which characters unlock each scene? Can't we compute $\lim_{n \to \infty}\frac{1+ \cdots +n}{n^2}=\lim_{n\to\infty}\frac{1}{n^2}+\cdots +\lim_{n\to\infty}\frac{n}{n^2}=0$? I just learned the definition of limits, and I learned that if $\{a_n\}, \{b_n\} $ converges, then $$\lim_{n\to \infty} (a_n+b_n)=\lim_{n \to \infty} a_n+\lim_{n \to \infty}b_n$$ holds.  And my teacher said that $\lim_{n \to \infty}\frac{1+2+3+ \cdots +n}{n^2}=\lim_{n\to \infty}\frac{\frac{n(n+1)}{2}}{n^2}=\frac{1}{2}$.  But can't we compute like  $$\lim_{n \to \infty}\frac{1+2+3+ \cdots +n}{n^2}=\lim_{n\to\infty}\frac{1}{n^2}+\lim_{n\to\infty}\frac{2}{n^2}+\lim_{n\to\infty}\frac{3}{n^2}+\cdots +\lim_{n\to\infty}\frac{n}{n^2}=0+0+\cdots+0=0$$? Drawing on an image with TikZ I understand that this command attempts to write to nowhere or a null device but what does 2&gt;&amp;1 mean here?  wget -q -O - http://yourwebsite.com/wp-cron.php?doing_wp_cron &gt; /dev/null 2&gt;&amp;1 How to prevent accidental clicks in the Save button when saving a node? I need to prevent accidental clicks in the Save button when a node is being saved.  I found this   which does exactly this. But the problem is that it uses javascript (jquery). Then if the user disable javascript this module is useless.  My problem is that in my website the user get points when creating nodes, so I have to prevent this in a more secure way.  How can I do this?   What do you think of these ideas?:  1) Maybe I would forbid the node being saved more than one time    programmatically instead of disabling the Save button.   2) Or better: I would allow the user to just save a new node every 5 minutes. Auto incrementing field based on groups within feature class? I am needing to auto increment a field based on groups within a feature class. I have 8 plots within a given polygon and I need to assign them an ID from 1-8 for each set of plots within each polygon. The polygon would have its own unique ID number to be used to group the plots.  I assume it would be an alteration of this:  rec=0 def autoIncrement():  global rec  pStart = 1   pInterval = 1   if (rec == 0):    rec = pStart   else:    rec = rec + pInterval   return rec lognormal distribution, standard-deviation and (physical) units I have a distribution of microparticles that follows a lognormal distribution. The cumulative distribution function thus is given by:  $$ F_X(x;\mu,\sigma) = \frac12 \operatorname{erfc}\!\left(-\frac{\ln x - \mu}{\sigma\sqrt{2}}\right) $$ $$ \mu = ln(M) + \sigma^2 $$  Now, the plot of the distribution function should be exactly the same no matter if the particle diameter $x$ is given in micrometers or meters (as long as I adapt the x-axis accordingly of course). However, this only works if I only convert $x$ and $M$, while not touching the numerical value of $\sigma$, and I don't understand why. $F_X$ has to be unitless, so $x$, $\mu$ and $\sigma$ should all have the same unit, right? What is the difference between IQueryable and IEnumerable? What is the difference between IQueryable&lt;T&gt; and IEnumerable&lt;T&gt;?    See also  that overlaps with this question. This is a very simple question but I believe it's nontrivial.  I would like to know if the following is true:      If $R$ and $S$ are rings and $R[x]$ and $S[x]$ are isomorphic as rings, then $R$ and $S$ are isomorphic.    Thanks!  If there isn't a proof (or disproof) of the general result, I would be interested to know if there are particular cases when this claim is true. Is there any Android XML documentation? Trying to solve     $f(x)$ is uniformly continuous in the range of $[0, +\infty)$ and $\int_a^\infty f(x)dx  $ converges.   I need to prove that: $$\lim \limits_{x \to \infty} f(x) = 0$$  Would appreciate your help! SQL query that concatenates values from duplicate rows in a single table Let's say I have a table of employees, like this:  Name     Sex     Role  Bob      M       Developer Joe      M       QA   Now, I have a problem with duplicated rows in this table. I will fix it sometime but it's not the issue. What I currently need is something that queries such a table:  Name     Sex     Role  Bob      M       Developer Bob      M       Janitor Joe      M       QA Joe      M       CEO   And will output the following rows:  Name     Role  Bob      Developer, Janitor Joe      QA, CEO   It doesn't matter to me if the "Role" will be split to separate columns or be a single column with multiple values.  Using SQL Server 2008 if it matters. Downloading from Play Store gives error 491 When I try to download anything from the Play Store it shows error 491 and can't finish the download. I have a Samsung Galaxy S 7582. How do I fix this? Modify footer used by elsarticle.cls