I'm wondering if anyone knows of a tool or plugin for QGIS that allows for multi-ring buffers.  I've found a post about doing multiple buffers one by one, but was hoping there was a way to do this all in one place.  I know in ArcMap that you can set the number of buffers you want and distance, so just hoping there's something out there in QGIS to accomplish this.
I'm new to QGIS and have no programming skills.  Is there an easy/uncomplicated way to create multiple buffers around a line feature?
What's the relationship between initial eigenvalues and sums of squared loadings in factor analysis? On the one hand I read in a comment  that:     You can't speak of "eigenvalues" after rotation, even orthogonal   rotation. Perhaps you mean sum of squared loadings for a principal   component, after rotation. When rotation is oblique, this sum of   squares tells nothing about the amount of variance explained, because   components aren't orthogonal anymore. So, you shouldn't report any   percentage of variance explained.   On the other hand, I sometimes read in books people saying things like:     The eigenvalues associated with each factor represent the variance   explained by that particular factor; SPSS also displays the eigenvalue   in terms of the percentage of variance explained (so factor 1 explains   31.696% of total variance). The first few factors explain relatively large amounts of variance (especially factor 1), whereas subsequent   factors explain only small amounts of variance. SPSS then extracts all   factors with eigenvalues greater than 1, which leaves us with four   factors. The eigenvalues associated with these factors are again   displayed (and the percentage of variance explained) in the columns   labelled Extraction Sums of Squared Loadings.   That text is from Field (2013) Discovering statistics using IBM SPSS, and this diagram accompanies it.    I'm wondering     Who is correct about whether it's possible to speak of eigenvalues after rotation? Would it matter if it was an oblique or orthogonal rotation?   Why are the "initial eigenvalues" different from the "extraction sums of squared loadings"? Which is a better measure of total variation explained by the factors (or principal components or whatever method is used)? Should I say that the first four factors explain 50.317% of variation, or 40.477%? understanding Debian dpkg package version numbers E: Package 'libpng12-0' has no installation candidate [ubuntu 16.10 Gnome] I tried to install WPS Office on my laptop (ubuntu 16.10 Gnome, 64 bit) with  Gdebi installer but it said   Dependency is not satisfiable: libpng12-0   Then I tried to open this library as follows  sudo apt-get install libpng12-0   But I encountered an error:  Reading package lists... Done Building dependency tree        Reading state information... Done Package libpng12-0 is not available, but is referred to by another package. This may mean that the package is missing, has been obsoleted, or is only available from another source  E: Package 'libpng12-0' has no installation candidate   Can anyone help? Thanks a lot Python dictionary: are keys() and values() always the same order? Why is the observable universe so big? How do I trim leading/trailing whitespace in a standard way? Is there a clean, preferably standard method of trimming leading and trailing whitespace from a string in C? I'd roll my own, but I would think this is a common problem with an equally common solution. I'm trying to display opportunities associated with an OpportunityLineItem on a Visualforce page on the OpportunityLineItem object   I have a problem in the select I do not know how to retrieve the OpportunityLineItem name in this request I have hard code the OpportunityLineItem name  public List&lt;OpportunityLineItem&gt; getOpp() {     return [SELECT TotalPrice, Opportunity.Name, Opportunity.StageName,                     Opportunity.Account.Name, Opportunity.id, Product2.Name              FROM OpportunityLineItem               WHERE Product2.Name='GenWatt Diesel 10kW'     ]; } Here's the very dumb way:  def divisorGenerator(n):     for i in xrange(1,n/2+1):         if n%i == 0: yield i     yield n   The result I'd like to get is similar to this one, but I'd like a smarter algorithm (this one it's too much slow and dumb :-)  I can find prime factors and their multiplicity fast enough.  I've an generator that generates factor in this way:  (factor1, multiplicity1) (factor2, multiplicity2) (factor3, multiplicity3) and so on...  i.e. the output of   for i in factorGenerator(100):     print i   is:  (2, 2) (5, 2)   I don't know how much is this useful for what I want to do (I coded it for other problems), anyway I'd like a smarter way to make  for i in divisorGen(100):     print i   output this:  1 2 4 5 10 20 25 50 100     UPDATE: Many thanks to Greg Hewgill and his "smart way" :) Calculating all divisors of 100000000 took 0.01s with his way against the 39s that the dumb way took on my machine, very cool :D  UPDATE 2: Stop saying this is a duplicate of  post. Calculating the number of divisor of a given number doesn't need to calculate all the divisors. It's a different problem, if you think it's not then look for "Divisor function" on wikipedia. Read the questions and the answer before posting, if you do not understand what is the topic just don't add not useful and already given answers. How to start itemize on same line as text? I've created a new environment called 'Example' like this:  \newenvironment{example}     {\textbf{Example:} \begin{itemize}}     {\end{itemize}}   The environment works fine, but the items are starting after the Example: text. Is it possible to start with the first item on the same line as the Example: text and vertically aline the rest of the items with the first item? What does "yield break;" do in C#? I have seen this syntax in MSDN: , but I don't know what it does.  Does anyone know? Minimum bounty on a question is now 100 rep? Here is some information we got : We know the value of $n$, with size $1043$. We know the value of $p$ (size $20$) and $q$ (size $1023$) as the factors. $e = 65537.$ $\varphi(n)$ = $(q-1)(p-1)$ When I calculated $\gcd$ and $\text{modinv}$, I got : $\gcd(e,\varphi(n)) = 65537$ $modinv(e,\varphi(n)) = 1 $ So we can tell that they are not relatively prime. So, how to compute the d, and get the value of m? I'm not that good with math, so I cant understanding well the theory. so can anyone please make an example implementation or write a clear formula? What are the mechanics by which Time Dilation and Length Contraction occur? What are the mechanics of time dilation and length contraction? Going beyond the mathematical equations involving light and the "speed limit of the universe", what is observed is merely a phenomenon and not a true explanation of why time dilates or length contracts.  It has been proven to work out, but do we know why?  Is it something that happens at a subatomic level? Can we use "there is" for plural nouns? Proper way to exit iPhone application? After upgrading from Ubuntu 13.04 server, the www pages won't display themselves.     Error 403 Forbidden You don't have permission to access / on this server.   I've changed access control saves from apache2.2 to apache2.4, but that didn't work. What else could I do? Neutron decay and electron anti neutrino $n\to p + e + \bar{\nu}_e$ Why do we need neutrino to explain neutron ? Is there any evidence regarding existence neutrinos in the context of $n\to p + e + \bar{\nu}_e$? Is there a way to change the color of text in a question? I just asked this question: .  The first answer I got totally missed the point of the question (that answer is now deleted).    I think my question would have been clearer if I could have changed the color of a (non-code) word to red, so I could show an example of what I wanted.  Is there a way to do this? How to I stop a launchd script from running on wake I have a simple launchd script that plays a sound every 30 minutes and it runs out of the user library ~/Library . It doesn't run if my machine is asleep, but does run the last event missed when the machine wakes. I think this is the expected behavior. My question is, how do I stop this happening. If I missed the half-hour event, I don't want it to be run at 20 minutes past the hour.  Here's the core of my script. It calls a Python script. I tried to put a block in the python script to check that I am within a few minutes of each 30 minutes, but that doesn't seem to work on wake. (Is it missing the system clock somehow?)  &lt;key&gt;ProgramArguments&lt;/key&gt; &lt;array&gt;     &lt;string&gt;/usr/local/bin/python3&lt;/string&gt;     &lt;string&gt;/Users/pheon/Documents/playsound.py&lt;/string&gt; &lt;/array&gt;  &lt;key&gt;StartCalendarInterval&lt;/key&gt; &lt;array&gt;     &lt;dict&gt;         &lt;key&gt;Minute&lt;/key&gt;         &lt;integer&gt;0&lt;/integer&gt;     &lt;dict&gt;         &lt;key&gt;Minute&lt;/key&gt;         &lt;integer&gt;30&lt;/integer&gt;     &lt;/dict&gt; &lt;/array&gt;   Here is a snippet from the python code which checks the time before playing the sound.  time0 = datetime.datetime.now() if (time0.minute % 30) &lt; 2:     subprocess.run(["/Users/pheon/bin/afplay-vol.sh", "1", bell],check=True) Why is the MacTeX distribution so large? Is there anything smaller for OS X? I would like to know how to install LaTeX on Mac 10.6 or higher.  But the MacTeX is some 1.28 GB file! Is there a smaller distribution I could install?  What exactly is TeX Live?