How to change the timeout between sudo sessions?
How often is the password asked for sudo commands? Where can I set it up?
Are expletives (cursing, swear words or vulgar language) allowed on SE sites? Is there any way to get a hat wider than widehat?  Why doesn't  \widehat{abcdefghijklmnopqrstuvwxyz}   really go over all of it? What commands (exactly) should replace the deprecated apt-key? After turning census block data into a raster, how do I redistribute the density to reflect land cover types I plan on rasterizing (terminology?) census block data relating to density to a regular 30 m by 30 m grid for use with NLCD data.  I then hope to distribute the density of the original census block among each result set of grid cells within the original polygon according to the land cover type dictated by the NLCD dataset.  For example, let's imagine a string of city blocks with a park, all found within one census block.  If within this census block the average density is 1000 people/km^2, we ultimately would want the resulting grid cell containing the park to have a lower population density than the grid cells containing the surrounding apartments.  This information may be captured by the NLCD dataset, with the park being classified as '21' (open but developed land) versus 24 for apartment buildings which could be classified as '24' (high density development).  Is there a method, or set of methods, within ArcMap that would allow me to:   Redistribute the density based on the NLCD value Perform this redistribution only within the original census block polygon   I don't know if this is possible, but I figured I would ask.  Edit  Here's what I have been trying:  I converted the census block data to a raster, snapping it to the NLCD land cover data and ensuring the output grid cells were the same size.  Each cell contains the same info as the original census block (housing umbers, population, etc). I have been trying to figure out a way to edit the new grid so that if the NLCD grid cell contains a land cover type that doesn't support a business or housing (park, forest, farm, etc.) that it's housing and population values area set to 0.  My next move was going to be figuring out how to subtract the non-residential/non-business grid cells area from the area of the original census block, and force a recalculation of the density.  Converted the altered census block layer to grid cells again, with each having the new density value, and once again set the cells' housing, population, and density values that don't support a business or housing (park, forest, farm, etc.) to 0.  Kind of circular, and I'm not sure of all the steps (raster calculator for editing individual grid cells based on another raster's grid cell value?), but it seems to logically work out if I can get the parts to work.  On the other hand, @dof1985's answer seems to simplify the first part of my workflow (by directing me to the correct toolset), but I will still have to nullify the grid cells where parks, etc., do exits after the density has been recalculated for the census data. "is" operator behaves unexpectedly with integers Why does the following behave unexpectedly in Python?  &gt;&gt;&gt; a = 256 &gt;&gt;&gt; b = 256 &gt;&gt;&gt; a is b True           # This is an expected result &gt;&gt;&gt; a = 257 &gt;&gt;&gt; b = 257 &gt;&gt;&gt; a is b False          # What happened here? Why is this False? &gt;&gt;&gt; 257 is 257 True           # Yet the literal numbers compare properly   I am using Python 2.5.2. Trying some different versions of Python, it appears that Python 2.3.3 shows the above behaviour between 99 and 100.  Based on the above, I can hypothesize that Python is internally implemented such that "small" integers are stored in a different way than larger integers and the is operator can tell the difference. Why the leaky abstraction? What is a better way of comparing two arbitrary objects to see whether they are the same when I don't know in advance whether they are numbers or not? \vphantom and superscripts How do I uninstall xcode 5 command line tools? Convert String to Integer in QGIS tables Under what condition we can interchange order of a limit and a summation? How to find roots of $X^5 - 1$? How to find roots of $X^5 - 1$? (Or any polynomial of that form where $X$ has an odd power.) How can I reliably and accurately identify the passive voice in writing or speech? I'm not interested in advice about whether or not to use it yet... I just want to know for sure what it is, so that I don't look as stupid as . As a  developer I'm used to running through constructors:    class Test {     public Test() {         DoSomething();     }      public Test(int count) : this() {         DoSomethingWithCount(count);     }      public Test(int count, string name) : this(count) {         DoSomethingWithName(name);     } }   Is there a way to do this in C++?  I tried calling the Class name and using the 'this' keyword, but both fail. Roman numerals used for ordinals Copying and pasting features using PyQGIS I have created a table join between two shapefiles which I've named 'OSMM' and 'Mastermap'. I want to copy and paste all features (polygons) without a match from the target layer ('Mastermap') into the parent shapefile ('OSMM'). I can't find any up-to-update code for QGIS 3.6. Here is my code so far: #1. loads the SHP files uri = 'C:/Users/xx/Downloads/OSMM.shp' vlayer = iface.addVectorLayer(uri,&quot;&quot;,&quot;ogr&quot;) uri = 'C:/Users/xx/Downloads/Mastermap.shp' vlayer = iface.addVectorLayer(uri,&quot;&quot;,&quot;ogr&quot;)  #2. Joins &quot;InvoiceNum&quot; from OSMM to Mastermap layerToJoin = QgsProject().instance().mapLayersByName('OSMM')[0] target = QgsProject().instance().mapLayersByName('Mastermap')[0] myJoin = QgsVectorLayerJoinInfo() myJoin.setJoinFieldName('InvoiceNum') myJoin.setTargetFieldName('InvoiceNum') myJoin.setJoinLayerId(layerToJoin.id()) myJoin.setUsingMemoryCache(True) myJoin.setJoinLayer(layerToJoin) myJoin.setJoinFieldNamesSubset(['InvoiceNum']) target.addJoin(myJoin)  #3. Selects NULL features from Mastermap params = { 'EXPRESSION' : '\&quot;OSMM_InvoiceNum\&quot; is NULL', 'INPUT' : 'C:/Users/xx/Downloads/Mastermap.shp', 'METHOD' : 0 } processing.run(&quot;qgis:selectbyexpression&quot;, params)  So how do I perform the PyQGIS version of Ctrl+C on 'Mastermap' and Ctrl+V into 'OSMM'? Presumably I will then need to use the following code: #5. Save the changes OSMM.commitChanges() A linear operator commuting with all such operators is a scalar multiple of the identity. During the Time War why didn't the Daleks blow up at least one TARDIS while in the Time Vortex? From the Cracks in time and space story arc it's known that if a TARDIS is blown up (possibly while in the Time Vortex) it rips creation itself apart. Also, from the Stolen Earth / Journey's End we learn the Daleks' masterplan which is subjugating creation itself via destroying it with the Reality Bomb (unfading Z-neutrino energy radiation).  In the Last Great Time War all sorts of temporal weapons were used and it's known that Daleks have the ability of time travel as well. Why didn't they use the Time Vortex back then to win the war once and for all via detonating a TARDIS while inside? I've taken multivariate calculus and am wondering if I can see a specific function where the order of taking the partial derivative matters. I've been told that there are some exceptions where $ \dfrac{\partial ^2 f}{\partial x \partial y} \ne \dfrac{\partial ^2 f}{\partial y \partial x} $, so I'm curious to see what this looks like.  EDIT: And why would this true? Hiding winforms app from taskbar Google spreadsheet sorting messes up cell comments I'm running into this weird problem with Google spreadsheets: if the cells have comments on them and I sort the spreadsheet, the rows sort but the comments stay in the same position, and don't move with the cells they're attached to.  In other words, the cells look like this:  A C  &lt;-- comment on this cell B   and then I sort by this column:  A B  &lt;-- comment remains on this cell (stays in position) C  &lt;-- comment should have remained attached to this cell   This means that sorting is completely broken and I can't use it at all, because I clearly need the cell comments to stay with the cell they're attached to.  Is this a bad bug in Google Spreadsheets, or am I missing something here? Total combinations from number of unique combination? How can you find count of the total combinations possible if you have the count of unique combinations? Suppose I need to form a sum of $3$ using $\{1,2\}$ Unique combn. $(1+1+1)$, $(1+2)$ hence '$2$' unique but total is '$3$' i.e, $(1+1+1)$, $(1+2)$, $(2+1)$ I know the elements used to make the combination Note: Number of unique combinations (ie. 2 here) is known. How can I find the total number of combination given the unique combinations?