I am using QGIS 2.18.9 and I have a problem. I dissolved a small map with about 1000 small regions into one big polygon, with Vector-&gt;geoprocessing tools-&gt;dissolve.    But after the dissolving there are little dots everywhere. After zooming in I found that these are all little holes in the layer.   Now I want the dissolved layer to not have any holes. Is there an easy way to do that?
The dissolve tool (vector>geoprocessing tools>dissolve) renders some artifacts on shapes with high number of polygons. I’m using a  with 3222 polygons and I’m trying to dissolve it using the field “municipio”, but when the dissolve tool ends calculating the new shape has some artifacts     Does anyone had a similar problem? How to work around it?  I’ve also used v.dissolve from GRASS and the dissolve polygon from SAGA, but the problem persists. I’ve used the same shapefile on ArcGIS 9.3 with the dissolve tool. None artifact/error was produced.  Edit 1  I'm trying to use the v.clean tool as sugested by WhiteboxDev. However I'm getting this error:     An error has occured while executing Python code:      Traceback (most recent call last):   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\gui\ProcessingToolbox.py",   line 181, in executeAlgorithm   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\algs\grass7\Grass7Algorithm.py",   line 511, in checkBeforeOpeningParametersDialog   File   "C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing\algs\grass7\Grass7Utils.py",   line 361, in checkGrass7IsInstalled   File   "C:\PROGRA~1\QGISCH~1\apps\Python27\lib\ntpath.py", line 96, in join   TypeError: object of type 'NoneType' has no len()      Python version:   2.7.4 (default, Apr  6 2013, 19:54:46) [MSC v.1500 32 bit (Intel)]      QGIS version:   2.4.0-Chugiak Chugiak, 8fdd08a      Python path:   ['C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins\processing',   'C:/PROGRA~1/QGISCH~1/apps/qgis/./python',   u'C:/Users/CERCOTRICHAS/.qgis2/python',   u'C:/Users/CERCOTRICHAS/.qgis2/python/plugins',   'C:/PROGRA~1/QGISCH~1/apps/qgis/./python/plugins',   'C:\PROGRA~1\QGISCH~1\bin\python27.zip',   'C:\PROGRA~1\QGISCH~1\apps\Python27\DLLs',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\plat-win',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\lib-tk',   'C:\PROGRA~1\QGISCH~1\bin',   'C:\PROGRA~1\QGISCH~1\apps\Python27',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\GDAL-1.11.0-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\PIL',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\jinja2-2.7.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\markupsafe-0.23-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\python_dateutil-2.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\pytz-2014.2-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\win32',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\win32\lib',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\Pythonwin',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\Shapely-1.2.18-py2.7-win32.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\six-1.6.1-py2.7.egg',   'C:\PROGRA~1\QGISCH~1\apps\Python27\lib\site-packages\wx-2.8-msw-unicode',   'C:\PROGRA~1\QGISCH~1\apps\qgis\python\plugins\fTools\tools',   'C:\Program Files\SpiderOak\shell_extension_lib\shared.zip']   Not entirely sure if this error is QGIS related... Any idea why I'm getting this error and how can I solve it?
Bought in, bought on, bought from, bought at? I was writing a toString() for a class in Java the other day by manually writing out each element of the class to a String and it occurred to me that using reflection it might be possible to create a generic toString() method that could work on ALL classes. I.E. it would figure out the field names and values and send them out to a String.  Getting the field names is fairly simple, here is what a co-worker came up with:  public static List initFieldArray(String className) throws ClassNotFoundException {      Class c = Class.forName(className);     Field field[] = c.getFields();     List&lt;String&gt; classFields = new ArrayList(field.length);      for (int i = 0; i &lt; field.length; i++) {         String cf = field[i].toString();         classFields.add(cf.substring(cf.lastIndexOf(".") + 1));     }      return classFields; }   Using a factory I could reduce the performance overhead by storing the fields once, the first time the toString() is called. However finding the values could be a lot more expensive.  Due to the performance of reflection this may be more hypothetical then practical. But I am interested in the idea of reflection and how I can use it to improve my everyday programming. Currently Running: macOS Catalina 10.15.1 Issue: Ever since I upgraded to Catalina, macOS is not allowing me to change read and write permissions on system protected files, hence, I am not able to tweak the system as per my likes and dislikes. Steps Tried To Solve The Issue: SIP, always remains . So, no question arises regarding any conflict with system integrity protection. I have also tried to force change the permissions on the system files I want to edit using certain brute force commands, which I can't recall the name of, right now. But, I have tried. As of now, I am still unable to change read and write permissions on system protected files and resources. The difference between "have a lunch" and "have lunch" Is there any difference between     I am not having a lunch tomorrow.   and     I am not having lunch tomorrow.   This is a follow up question of : . Linux Command Not Functioning As Alias The meaning of various equality symbols In sysctl, the /proc/sys/net/ipv[46]/conf/ keys have the following subkeys: all, default, and a key for each network interface. For example, on a machine with a single network interface eth0, it will look like this:  iserv ~ # ll /proc/sys/net/ipv[46]/conf/ /proc/sys/net/ipv4/conf/: insgesamt 0 dr-xr-xr-x 0 root root 0 12. Sep 23:30 all/ dr-xr-xr-x 0 root root 0 12. Sep 23:30 default/ dr-xr-xr-x 0 root root 0 12. Sep 23:30 eth0/ dr-xr-xr-x 0 root root 0 12. Sep 23:30 lo/  /proc/sys/net/ipv6/conf/: insgesamt 0 dr-xr-xr-x 0 root root 0 12. Sep 23:30 all/ dr-xr-xr-x 0 root root 0 12. Sep 23:30 default/ dr-xr-xr-x 0 root root 0 12. Sep 23:30 eth0/ dr-xr-xr-x 0 root root 0 12. Sep 23:30 lo/   All the respective settings exist in each key separately. For example, if I want to disable IPv6 Router Advertisements with the accept_ra value, this value exists four times:  iserv ~ # sysctl -a 2&gt;/dev/null | grep "accept_ra " net.ipv6.conf.all.accept_ra = 1 net.ipv6.conf.default.accept_ra = 1 net.ipv6.conf.lo.accept_ra = 1 net.ipv6.conf.eth0.accept_ra = 1   My question now is: which of these values do I need to change? I figured all (to change all existing interfaces) and default (to change all new interfaces that may appear later), but changing these still leaves the value at 1 for lo and eth0:  iserv ~ # sysctl -w net.ipv6.conf.all.accept_ra=0 net.ipv6.conf.all.accept_ra = 0 iserv ~ # sysctl -w net.ipv6.conf.default.accept_ra=0 net.ipv6.conf.default.accept_ra = 0 iserv ~ # sysctl -a 2&gt;/dev/null | grep "accept_ra "   net.ipv6.conf.all.accept_ra = 0 net.ipv6.conf.default.accept_ra = 0 net.ipv6.conf.lo.accept_ra = 1 net.ipv6.conf.eth0.accept_ra = 1   Will the machine now accept Router Advertisements on eth0, or will it not? Scamming a scammer? I have seen many questions like:      My question is: what happens if you receive this money (without doing anything or giving your bank account number) but do not do anything scammer wants?  I especially want to know about what happens with the money you got and possible legal consequences.    Is it considered yours because scammer transfered it to you? Do you have to return it? If yes, to whom and in what form? And finally, how is it that scammers are just sending money to random people? Aren't they scared that someone will simply not return it? I understand that this may be stolen money, but it surely took some effort (cash/time) to "acquire" it, so why are they just sending it away? How close would you have to be to the merger of two black holes, for the effects of gravitational waves to be detected without instruments? future or present with when What happens if you are refused entry between two countries? Last month, I was travelling on a backpacking trip across Russia and the Baltic states (Schengen zone). I'm an Indian by nationality. So I had to get the respective single entry visa for Russia and Schengen Europe.  At the border crossing into Estonia by road (at Ivangorod-Narva), I exited the Russian border with an exit stamp (so now I can't go back to Russia since I had a single entry visa). When I was at the immigration checkpoint of Estonia, I was heavily questioned on the intent of my travel to Europe while entering Estonia by road.   Though I finally got into Europe, It got me wondering - what happens if a foreign national is denied entry into a country not at the airport but by land between 2 countries he cannot go into ?  Generally, if you are denied entry at the airport the airline has the obligation to fly you back to your country. But what happens when you are stuck between two countries and you cant get into either ? What happens to you then ? Is there a difference between DataTable.Clear and DataTable.Rows.Clear? I kust realized that some other PC is also getting assigned a IP address (DHCP Lease) from my modem. I am sure this is not one of the PCs in my home.  My modem was using WEP security. I know WEP is far less secure and WPA is better, but this actually is a borrowed modem, and I did not know that WEP was used.  I immediately did the following : On My Modem    Changed the encryption mode from WEP to WPA   Changed the password   After this I do not see the intruder PC on the DHCP list.  On my Mac:     Changed the permissions on the public folder to "everyone - no access"   Turned off "File Sharing" in System Preferences (But I would want to turn it back on sometime)   My mac is the one that is always on, Both the admin user and the user I normally use are password protected.  Is the above sufficient? Should I do something more?  Also, is WPA security sufficient? Should I take other steps? Reprojected MODIS NDVI has range from -32768 to 32767, expected -1 to 1 How do I run two isolated instances of firefox? My online friend is asking for money in order to visit my home country. Is this a legit request or a scam? On Travel.SE we often see questions about a person (usually a love interest) asking for money to pay for airfare, visas, permits and other expenses. For example        What general advice can be given in such situations to the person asking the question? Is it all a scam or can there be legitimate situations in which an online friend could be asking for money? What is the default bibliography package and backend in LaTeX? According to , biblatex and natbib are packages while biber and bibtex are backends. If I don't specify either any package or any backend, it still compiles fine. Which package and backend combination is being used in this case?  demo.tex  \documentclass{article} \begin{document}  \nocite{*} \bibliographystyle{ieeetr} \bibliography{pub}  \end{document}   pub.bib  @article{janssen1996evaluation,     title={Evaluation of the DNA fingerprinting method AFLP as a new tool in bacterial taxonomy},     author={Janssen, Paul and Coopman, Renata and Huys, Geert and Swings, Jean and Bleeker, Marjo and Vos, Pieter and Zabeau, Marc and Kersters, Karel},     journal={Microbiology},     volume={142},     number={7},     pages={1881--1893},     year={1996},     publisher={Soc General Microbiol} }  @article{vos1995aflp,     title={AFLP: a new technique for DNA fingerprinting},     author={Vos, Pieter and Hogers, Rene and Bleeker, Marjo and Reijans, Martin and Van de Lee, Theo and Hornes, Miranda and Friters, Adrie and Pot, Jerina and Paleman, Johan and Kuiper, Martin and others},     journal={Nucleic acids research},     volume={23},     number={21},     pages={4407--4414},     year={1995},     publisher={Oxford Univ Press} } Books for self-studying time series analysis? Mapping Russia - Int'l dateline splitting polygon ColA                  Col B              ColC Project A            A.pdf               A.pdf Project B                                No Link   I have a list of project records. One column (e.g., B) may have a reference to a pdf file. If I create a formula   =if(isblank(B2),"No Link",hyperlink(folderURL + B2),B2)   What I want is to place a hyperlink on only those rows where column B contains a pdf reference, and insert text "No Link". I get the proper text values, but in all rows have the hyperlnk default appearance and behavior -- Excel seems to be creating "phantom links" out of the "No Link" cells.     Clicking on the "No Link" value in Col C activates an attempt to open the file listed in Col B, which returns a No file found error.