I need to create a mask to cover the rest of the world outside of a single city. ().  I've been told by support to open those boundaries "create a new geospatial file that would be made up of a rectangle that covers the whole earth with a hole in the shape of your city in the middle."   From there, I need to upload that file to Mapbox Studio and add it to cover the rest of the world outside of my city. I'm looking to style OpenStreetMap in Mapbox afterwards for that city. So this is a workaround for not being able to edit a single city in Mapbox Studio.  How would I create this mask?
I'm using python in QGIS. I have a layer of polygons (its a result of some earlier dissolving and has no overlapping polygons but some holes and islands in holes etc). I want to build a new layer which contains one polygon representing a bbox of the first layer with each polygon cut from it.  Essentially I want to "invert" the layer I have so that where the was polygon, now there is not, and where there was not polygon now there is. All inside a bounding box of the original layer.  I can build a bbox easily and I tried to "subtract" the polygon layer from my new bbox polygon layer but the process slows to a stop and then crashes my PC. Here's the algorythm  processing.runalg("qgis.difference","path/to/polygon.shp","path/to/bbox.shp","path/to/result.shp")   I dont care about attributes (obviously). I just need to cut one set of polygons from one larger polygon.  It seems so simple, I wish I could find a simple command or script to acheive this. As stated at the top I'm looking for a solution in python in QGIS.
Electromagnetic wave properties of light vs radio waves What is the difference between "why are you worried" and "why you are worried"? Sending `time` command into text file I want to get the result of time command into a text file but it's not working it only put blank space in the text file.  I already tried this commands,  A-  $ x=`time` $ echo $x &gt; log.txt $ cat log.txt  $   B-   $ time &gt; log.txt  real    0m0.000s user    0m0.000s sys     0m0.000s $ cat log.txt  $   C-  $ time &gt; log.txt 2&gt;&amp;1  real    0m0.000s user    0m0.000s sys     0m0.000s  $ cat log.txt  $    What I really want is this.   $ time &gt; log.txt $ cat log.txt  real    0m0.000s user    0m0.000s sys     0m0.000s Can I make a public directory under a private directory? I have a personal folder /a/b on the server with permission 700. I don't want others to list the contents in /a/b. The owner of /a is root.  Now I need to open the full authorities of directory /a/b/c to all users.  I changed the permission of /a/b/c to 777 but it is still inaccessible for others. What's the meaning "them" here? On every boot up I get this:    For about 10 seconds (or more) before the "normal" Ubuntu Gnome loading screen and the login screen comes up.  I've read some questions and a bug report about this already, but this problem was dismissed as a minor inconvenience or there were no real solutions (that worked for me). For me, this problem leads to an unacceptable slow boot compared to Ubuntu (Unity) or Windows.  Does anybody know how to fix this or is this a "feature" of Ubuntu Gnome and not a bug? Theorem 3.2 Rudin -- How is 0 concluded? I'm having trouble understanding why the arbitrariness of $\epsilon$ allows us to conclude that $d(p,p')&lt;0$. It seems we could likely conclude a value such as $\frac {\epsilon}{100}$ couldn't we?? The other idea that would normally work is the limit (as $n$ approaches $\infty$, $p$ approaches $p'$) but that would mean we are further in another sequence which would have same problem Thanks in advance   $\ $  $\ $  $\ $   Definition of Convergence     A sequence $\{ p_n \}$ in a metric space $X$ is said to converge if there us a point $p \in X$ with the following property: For every $ \epsilon&gt;0$ there is an integer $N$ such that $n \ge N$ implies distance function $d(p_n, p) &lt; \epsilon.$ creating a tar archive without including parent directory I am trying to create a graphical program for my script.  Inside the script I use tar to create a tar archive.  From the graphical program I get the full name of file that I want to create a tar archive.  tar -cvf temp.tar /home/username/dir1/dir2/selecteddir    My tar archive includes home, username, dir1, dir2 and selecteddir while i want tar to create archive only including selecteddir. Is there any noun in English which changes the first letter in the plural? Plenty of nouns change the second letter to become plural (man->men, goose->geese) but does anything change its first letter.  I've hunted high and low over the internet, and spent ages browsing the questions at  but I can't find anything. Overlapping text in Database Schema SEDE Over at , there is overlapping text in the Database Schema under Close-As-Off-Topic-Reason-Types:  that makes it really hard to read.  This is also happening underneath &quot;Pending Flags&quot;, and seemingly with every long line in the schema.  This would be fine if you could increase the width of the list as you can with the height, which would in theory separate the lines, but you can't.  Can we fix this, please?  UPDATE: I have found that  post is almost exactly the same as mine, but steady on with duplicate votes.   comment says that it will be fixed, but that question was asked more than five years ago, and in that time the problem has not been resolved.  UPDATE 2: It seems that  would help.  I changed a little CSS/HTML, and came up with this:  Although mine is a little cruder than it could be.  This is just an example. How can I resize NTFS partition in GParted? Best way to center a  on a page vertically and horizontally? Best way to center a &lt;div&gt; element on a page both vertically and horizontally?  I know that margin-left: auto; margin-right: auto; will center on the horizontal, but what is the best way to do it vertically, too? I want to write as a math fraction 1/4 " ( a quarter of inch). I want to write this fraction out of an equation because is a characteristic of an element. When functions commute under composition I will like to know some of the android emulators that work really well with Ubuntu 11.10 and above. I want to try 'whatsapp' on Ubuntu through an android emulator. Thanks in advance Short Story about interminable rain on Venus How does one prove that if $n \mid (a^{n}-b^{n}) \ \Longrightarrow$ $ \displaystyle n \mid \frac{a^{n}-b^{n}}{a-b}$ where $a,b, n \in \mathbb{N}$.  What i thought of is to consider $$(a-b)^{n} \equiv a^{n} + (-1)^{n}b^{n} \ (\text{mod} \ n)$$ and if we suppose that $n$ is odd then we have, $$(a-b)^{n} \equiv a^{n} -b^{n} \ (\text{mod} \ n)$$ and since $n \mid (a^{n} - b^{n})$ we have $$(a-b)^{n} \equiv 0 \ (\text{mod} \ n) $$  I think i am far away from the conclusion of the problem, but this is what i could work on regarding the problem. How can I test for a player wearing specific armor? How can I test for a player that is wearing an iron helmet named "test1" and an iron chestplate named "test2" in Minecraft Version 1.12? Does $\int_a^bf(x) = 0$ imply $f(x) = 0$ for a Riemann Integral function? Let $a &lt; b$ and $f:[a, b] \rightarrow \mathbb R$ be a Riemann integral function. Suppose that $f(x) \geq 0$ for all $x \in [a, b]$. I want to show whether $\int_a^bf(x) = 0$ implies $f(x) = 0$ or not, but I'm not sure where to start. I don't know much about Riemann integral functions in general. I only know that $$\underline \int_a^b f= \overline \int_a^b f.$$ Also, I know the fact that if $f$ is continuous, then $f(x) = 0$ for all $x\in [a, b]$. Can anyone provide any hints for me, because I'm really confused about this whole thing. If $g \circ f$ is surjective, show that $f$ does not have to be surjective?