I'm using demographic data in California by census tract, and I'd like to be able to group those census tracts into 4 regions with an equal population in each region. Any recommendations for how to do this in QGIS?   I'd like to be able to do something like the process FelixIP takes in the answer to this question but I don't completely understand all of the steps:    Any clarification to that answer as well?
I have a shapefile with 3800 polygons representing the smallest administrative areas in Ireland. Many of these, in rural areas, have tiny populations, under 100 people. In urban areas, all would have adequate populations.  For each area I have a population figure, and various other attributes, all of which can be intelligently summed to give valid results for areas produced by combining the smaller areas.  I need to merge the areas to get say, 500 or 600 areas of reasonable population. I need to leave the larger (in population) areas alone, where possible. I would greatly prefer to do this automatically. This is necessary for model fitting purposes, primarily.  I've looked at a number of the dissolve questions here:   'Batch Dissolve Polygons based on Attributes in QGIS or FWTools' I think would require me to know which areas to merge, when this is what I need to calculate. 'Practical way of managing polygons and unions of them' and 'How do dissolve polygons from shapefile using open source tools?' have the same issue.   Any suggestions?
Formal writing: "…for my colleagues and {I/me/myself}."? I'm currently using Cambridge English Advanced 1. It's a book that contains past examination papers, and includes numerous samples of authentic writing. This material helps, candidates and teachers, understand what the examiners are ‘testing’ and how these papers are marked. The assessment covers four categories: content, communicative achievement, organisation and language. Each category is awarded a mark between 1 and 5, so the maximum score is 20, and each mark has a brief note attached by the examiner. Any errors of punctuation, orthography, grammar, appropriacy, and vocabulary are left intact. In fact, there are no corrections because the  ‘examiner’ does not specify where the errors lie. This can be frustrating, even though spelling mistakes are rare at the advanced level, and errors in style, collocation or register are still relatively easy to identify, sometimes I'll read a phrase that forces me to ponder.  Dear Director, [ TEXT ] To conclude, this letter is a polite request to cover the costs of a 2 month language course for my colleagues and me. We would be very pleased if the company would do us this favour. Yours sincerely John Smith  The following marks were awarded Content                    5    blah, blah, … Communicative Achievement  2    blah, blah, …     Organisation               3    blah, blah, … Language                   3    blah, blah, …  I am able to pick out six minor errors in that brief extract, maybe some users will identify more, maybe some will identify fewer, and maybe some will say that the language used is perfectly acceptable. But if I can help a candidate attain that elusive B,  I would be delighted. I am interested in (what could be) the 7th error, emphasised in bold. Because the letter of proposal is formal, I feel the phrase, for my colleagues and me, is jarring. I want to change it to for my colleagues and I, but the antecedent requires an object. You would not say: “This is a request to cover the cost […] for I”. So, why use the subject pronoun I in the expression “my colleagues and…”?  Could I use instead, myself?  Which of the following is preferable in a formal written proposal?    …for my colleagues and me …for my colleagues and I …for my colleagues and myself  EDITED: I found a   of the writing sample (11/11) if anyone is interested.  I've looked at the following question,  Some answers appear to be contradictory, the accepted answer says using  I and me are both grammatical, which in my example is not true. Moreover, there's no mention of myself, as a possible solution, in the question. Many sysv init scripts used a corresponding file in /etc/default to allow the administrator to configure it. Upstart jobs can be modified using .override files. How do I override or configure systemd units, now that systemd is the default in Ubuntu? Product of path connected spaces is path connected Passing data between view controllers Let $A\in M_{n\times n}(\Bbb R)$ so that $I\notin span(A,A^2,...,A^n)$. Prove that $\det(A)=0$. Let $A\in M_{n\times n}(\Bbb R)$ so that $I\notin span(A,A^2,...,A^n)$. Prove that $\det(A)=0$.   I was thinking of showing $A$ is not invertible, meaning it has an eigenvalue of $0$. Since no matter the power you give to $A$, it is still not the identity, you can deduce that at least one eigenvalue is indeed $0$. However this doesn't work if you have different eigenvalues in the Matrix, so I got stuck.  Help will be most appreciated. How do I remove duplicates from a C# array? I have been working with a string[] array in C# that gets returned from a function call. I could possibly cast to a Generic collection, but I was wondering if there was a better way to do it, possibly by using a temp array.  What is the best way to remove duplicates from a C# array? How to enter the Default Keyring password via the command line? Is there a way to enter the default keyring password using the command line?   For instance:  You have a remote setup of Ubuntu 10.10 thats set to auto login. You don't want to remove  the keyring password.  All right the system boots up and logs in automatically, then asks for the keyring password now at this point you can create ssh connections but you can't remote desktop.   What can you do to enter the keyring password at this point?  Also, to better clarify, this is from a remote connection using the command line. Heroku deployment failed because of sqlite3 gem error Ability to retract reopen/delete votes It seems that now we can retract close votes but we cannot retract reopen votes or delete votes.  I am trying to retract my reopen vote  but it does not allow me to.  Can we have that ability? Shortest distance between $2$ lines with direction vectors Let L1 be the line passing through the point $P_1=(−11, 10, −1)$ with direction vector $\vec d_1=\begin{bmatrix}−2\\ 3\\ −1\end{bmatrix}t$, and let $L_2$ be the line passing through the point $P_2=(−8, 9, 10)$ with direction vector $\vec d_2=\begin{bmatrix}−1\\ 3\\1\end{bmatrix}t$. Find the shortest distance, $d$, between these two lines, and find a point $Q_1$ on $L_1$ and a point $Q_2$ on $L_2$ so that $d(Q_1,Q_2) = d$.   I dont really understand how to properly approach this question, how do i start? Find the number of solutions of $a_0+a_1+a_2=17$ if $2\le a_0\le 5$,   $3\le a_1\le 6$, $4\le a_2\le 7$.   This is an exmaple given by my professor, and his solution is:       The number of solutions to this equation satisfying the given   constraints is equal to the coefficient of $x^{21}$ in the expression   $$\left(\sum_{n=2}^5x^n\right)\left(\sum_{n=3}^6x^n\right)\left(\sum_{n=4}^7x^n\right)=x^9\left(\sum_{n=0}^3x^n\right)\left(\sum_{n=0}^3x^n\right)\left(\sum_{n=0}^3x^n\right).$$   This must be 3, since the coefficient of $x^8$ in $(1+x+x^2+x^3)^3$ is   3.   I understand actually nothing here. The expression of summation just pops up, and then comes the answer. What I only know that the idea of generating function is used here. Can someone help explain how the steps in the solution come? How to download an MP3 track from a YouTube video Better explanation of the common general relativity illustration (stretched sheet of fabric) I've seen many science popularisation documentaries and read few books (obviously not being scientist myself). I am able to process and understand basic ideas behind most of these. However for general relativity there is this one illustration, which is being used over and over (image from Wikipedia):    I always thought that general relativity gives another way how you can describe gravity. However for this illustration to work, there needs to be another force, pulling the object down (referring to a direction in the attached image). If I put two non-moving objects in the image, what force will pull them together?  So where is my understanding incorrect? Or is general relativity not about explaining gravity and just describes how heavy objects bends spacetime (in that case the analogy is being used not correctly in my opinion)?    UPDATE Thank you for the answers and comments. Namely the XKCD comics is a spot on. I understand that the analogy with bent sheet of fabric pretty bad, but it seems that it can be fixed if you don't bent the fabric, but just distort the drawn grid.   Would you be so kind and answer the second part of the question as well - whether general relativity is explaining gravitational force. To me it seems that it is not (bending of spacetime simply can not affect two non-moving objects). However most of the time it is being presented that it does. 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. sudo apt update always giving Clearsigned file isn't valid, got 'NOSPLIT' (does the network require authentication?) How to rename wp-includes folder? Is there a way that we could rename wp-includes folder   I have found out there are ways to do for other folders. But how do we do it for wp-includes folder? Laplace transform of integral constant SQL Server 2012 Page Life Expectancy resets to 0 after about 50 days I've noticed an odd behavior on a 2-server HA cluster and I was hoping someone could confirm my suspicion, or maybe offer some other explanation... Here is my setup:   A 2-server SQL 2012 SP1 installation SQL AlwaysOn HA has been enabled for a few databases CPUs are 2.4GHz, 4 cores RAM is 34 GB (it is an AWS instance, hence the odd number) Resource utilization is relatively low - each server has 14+ GB memory free, and SQL is not capped on how much memory to use Disk access time is fine - rarely going over 15ms/Read or Write Databases are not big - 1 GB, 1.5 GB, 7.5 GB SQL server process is using 16 GB Private Bytes, 15 GB Working Set   Overall, no resource issues are noted. Now for the odd part. SQL is not restarted (process has been running for almost 6 months) but it seems that every ~50 days, the Page Life Expectancy counter drops to (almost) 0. Up until that point it climbs steadily, no drops. Here is a perf graph:    When I look at the counter data (I don't have the exact number, just an hourly aggregation) it seems the PLE counter value reached about 4,295,000 sec (roughly 50 days) every time (at least every time I have data for).   My crazy theory is that the PLE number is held as milliseconds as an unsigned long int (which has a limit of 4,294,967,295) and at 49.71 days it resets, either by design, or because of a bug. This would explain the behavior of the two servers and the identical pattern they have. Or it could be something totally different and I am just not making any sense. :)  Has anyone seen anything like that, or can explain this behavior?  P.S. I saw  post, but my case seems slightly different.  P.P.S. This is a repost - I originally posted it , but was advised the audience here is more appropriate.  Thanks! How do I pass a function as a parameter to in elisp? I'm trying to pass one method to another in elisp, and then have that method execute it.  Here is an example:  (defun t1 ()   "t1")  (defun t2 ()   "t1")  (defun call-t (t)   ; how do I execute "t"?   (t))  ; How do I pass in method reference? (call-t 't1) Is there a catch-all place on the Stack Exchange network where one can post any question that does not obviously belong to the Stack Exchange sites? Is there a catch-all place somewhere on the Stack Exchange sites where one can post a (any) question that does not obviously belong to any of the Stack Exchange sites?  Sometimes I have questions but I don't want to ask them on other sites (no need for names). I prefer to post it on the Stack Exchange network for various reasons.  If there isn't, are there plans for one? I imagine that if such a site exists, questions on that site can also be moved to other more specific sites when they exists, and it's not to be used to post questions which obviously belong to a specific Stack Exchange site.