I'm trying to extend xml.ElementTree.Element. The problem is that the constructor gives me a ready made Element instance which I cannot extend without tampering with the source code of xml.  Is there a way to initialize a class that inherits from Element and copy the whole Element attributes into the SubClass?  import xml.ElementTree as ET  root = ET.parse('file.xml').getroot() # retrieves Element instance  class ExtendedElement(ET.Element):     def __init__(self, element):         pass         # somehow initialize the ExtendedElement instance         # with all methods and attributes of element         # without copying each attribute individually         # ie self.attrib = element.attrib      def custom_method(self):         print(self.attrib)  ext = ExtendedElement(root)  ext.custom_method()  assert root.attrib == ext.attrib assert list(ext) == list(root)   Usually I would just go on and call self.__dict__.update(element.__dict__), however Element doesn't seem to have a __dict__ (how is this even possible?).   I want to avoid copying all attributes individually as I might miss some hidden ones without knowing.
I'm trying to understand the use of super(). From the looks of it, both child classes can be created, just fine.   I'm curious to know about the actual difference between the following 2 child classes.  class Base(object):     def __init__(self):         print "Base created"  class ChildA(Base):     def __init__(self):         Base.__init__(self)  class ChildB(Base):     def __init__(self):         super(ChildB, self).__init__()  ChildA()  ChildB()
I typically have two needs:  Scenario A. Change a single PDF page.  In this case I have a PDF but not the original source file used to create the PDF. I don't want to try to recreate the document from scratch. I'd like to open the PDF and change a few things. A good example of this scenario: I was responsible for planning a big event at a campground site, I had a PDF of the site. I wanted to start with that document, highlight some parts, add some labels, remove some parts that weren't relevant.   or   Scenario B. Combine PDFs or extract page(s) from a PDF  This scenario usually arises because I want a single PDF deliverable that is made up of parts that are best created in different programs. In this case I have the source files for all the documents but they don't play well enough together to easily create a single PDF deliverable. For part of it, I may want to use Libre Office Writer. For another page I may want to use Gimp. Still another page I may use Libre Office Calc. I could use Writer as the master document and embed images or the Calc object into that, but for ultimate control, you can't beat separate PDF documents that are then combined.  What are the best tools / processes for editing PDFs in Ubuntu? Pointwise convergent and total variation I'm preparing for a test for real analysis and I came across this problem in Royden's book:  Let $\{f_n\}$ be a sequence of real valued functions on $[a,b]$ that converges pointwisely on $[a,b]$ to the real valued function $f$. Show that $TV(f) \leq \liminf  ~TV(f_n)?$  This looks quite similar in form to Fatou's Lemma to me, but can't find any way to establish TV with integration, can anybody please help?  (TV is short for total variation) I want to resize the Unity launcher. Is that possible? Reducing resolution of huge categorical raster in QGIS? In my CMS, I noticed that directories need the executable bit (+x) set for the user to open them. Why is the execute permission required to read a directory, and how do directory permissions in Linux work? What is the difference between Θ(n) and O(n)? Sometimes I see Θ(n) with the strange Θ symbol with something in the middle of it, and sometimes just O(n). Is it just laziness of typing because nobody knows how to type this symbol, or does it mean something different? Why do statisticians say a non-significant result means "you can't reject the null" as opposed to accepting the null hypothesis? Traditional statistical tests, like the two sample t-test, focus on trying to eliminate the hypothesis that there is no difference between a function of two independent samples. Then, we choose a confidence level and say that if the difference of means is beyond the 95% level, we can reject the null hypothesis. If not, we "can't reject the null hypothesis". This seems to imply that we can't accept it either. Does it mean we're not sure if the null hypothesis is true?   Now, I want to design a test where my hypothesis is that a function of two samples is the same (which is the opposite of traditional statistics tests where the hypothesis is that the two samples are different). So, my null hypothesis becomes that the two samples are different. How should I design such a test? Will it be as simple as saying that if the p-value is lesser than 5% we can accept the hypothesis that there is no significant difference? Steam doesn't start - Segmentation faults I'm answering a question with a suggestion to use rename, and I realize I don't know what package it comes from (as part of the answer, I imagine saying something like "if you don't have rename, it's installed as part of [package]").  man rename tells me to SEE ALSO: mv(1), perl(1) - so my first thought is that it was installed with perl.  A related answer, , helps me figure out that the perl package includes prename but not rename - and it turns out that my /usr/bin/rename points to /etc/alternatives/rename which points to /usr/bin/prename  So this is still kind of confusing.  Did /etc/alternatives/rename point somewhere else before I installed perl?  Is there a general way to tell which package something comes from? How prove this $\prod_{1\le i<j\le n}\frac{a_{j}-a_{i}}{j-i}$ is integer let $a_{i},i=1,2,\cdots,n$ be postive integer ,show that $$1^{n-1}2^{n-2}\cdots (n-2)^2(n-1)|\prod_{1\le i&lt;j\le n}(a_{i}-a_{j})$$  I know this $\prod_{1\le i&lt;j\le n}(a_{i}-a_{j})$ is  Vandermonde  determinants,and I found $$1^{n-1}2^{n-2}\cdots (n-2)^2\cdot (n-1)=1!2!3!\cdots (n-1)!=\prod_{1\le i&lt;j\le n}(j-i)$$ we only prove $$\prod_{1\le i&lt;j\le n}\dfrac{a_{j}-a_{i}}{j-i}$$ is integer  maybe consider Vandermonde determinants ? But I can't prove this How does ownership in fractional shares work? I've been trying to find out some more information about fractional shares, and how they work. I understand conceptually, you own x% of a share rather than x "full" shares, but I'm curious about how such a system is implemented.  As I understand it, in a "traditional" purchase of shares, the role of a broker is to act as an executor on your behalf, and does not hold any assets themselves. In the case of a fractional share, is this then not the case? For example, the broker holds the complete shares, and then just ensures that they keep an internal record of each partial owner in their system? So there would be no external record of partial ownership?  Thanks! Argument list too long error for rm, cp, mv commands How can I transfer large files from Linux to iPad over a cable or wifi? I am looking for a way to transfer large files to the iPad without using iTunes or pushing to and pulling from a remote server.  I run an Ubuntu laptop as my only OS at the moment and want to be able to transfer movies to my iPad.  I currently transfer most of my files by way of the dropbox app which works well for small files but is quite slow for larger files and eats up my bandwidth.  Ideally I'd like to be able to transfer over a cable or through WiFi.  Thanks for any tips. How do you assert that a certain exception is thrown in JUnit 4 tests? How can I use JUnit4 idiomatically to test that some code throws an exception?  While I can certainly do something like this:  @Test public void testFooThrowsIndexOutOfBoundsException() {   boolean thrown = false;    try {     foo.doStuff();   } catch (IndexOutOfBoundsException e) {     thrown = true;   }    assertTrue(thrown); }   I recall that there is an annotation or an Assert.xyz or something that is far less kludgy and far more in-the-spirit of JUnit for these sorts of situations. Let $X$ be a topological space. The diagonal of $X \times X$ is the subset $$D = \{(x,x)\in X\times X\mid x \in X\}.$$   Show that $X$ is Hausdorff if and only if $D$ is closed in $X \times X$.   First, I tried to show that $X \times X \setminus D$ is open using the fact that $X \times X$ is Hausdorff (because $X$ is Hausdorff), but I couldn't find an open set that contains a point outside $D$ and is disjoint to it... Do I need to have antivirus software installed? Say if I define a power series over some arbitrary field $F$ as   $$a = \sum^{ \infty }_{i = 0} a_{i} X^{i} $$  Then can I say:  $$ab = \sum^{ \infty }_{i = 0} \sum^{ \infty }_{j = 0} a_{i} b_{j} X^{i + j} $$ I have downloaded Aptana Studio 3 and created the following launcher item for using Alacarte:  file: alacarte-made.desktop  [Desktop Entry] Comment= Terminal=false Name=Aptana Studio 3 Exec=AptanaStudio3 Type=Application Icon=/opt/Aptana-Studio-3/icon.xpm   Then, when I add the icon to the favorites and opens the Aptana Studio 3 I get two icons for it, one for launching new instances, and one for the currently running instance as per the following screenshot:    How do I force the application to use the same icon added to the favorites? Modernist Cuisine recommends that for longer sous vide cooking (times greater than 36 hours) that bags are vacuum sealed rather than just using the water displacement method to remove the air from a ziploc bag.  What is the reason for this? Will I be losing something essential if I just use a regular ziploc bag without vacuum sealing? abhigenie92@ubuntu:~$ (sleep 2; echo $BASH_SUBSHELL ;sleep 2) 1 abhigenie92@ubuntu:~$ (sleep 2; echo $BASH_SUBSHELL ;sleep 2)&amp; [1] 3297 abhigenie92@ubuntu:~$ 1  [1]+  Done                    ( sleep 2; echo $BASH_SUBSHELL; sleep 2 )   What happens when launch it as a background process, why don't I get the prompt back and I have to press Enter? In both cases it launches a child shell.