How to remove duplicate items from a list using list comprehension? How to remove duplicate items from a list using list comprehension? I have following code:  a = [1, 2, 3, 3, 5, 9, 6, 2, 8, 5, 2, 3, 5, 7, 3, 5, 8] b = [] b = [item for item in a if item not in b]   but it doesn't work, just produces identical list. Why its producing an identical list?
How do you remove duplicates from a list whilst preserving order? Is there a built-in that removes duplicates from list in Python, whilst preserving order? I know that I can use a set to remove duplicates, but that destroys the original order. I also know that I can roll my own like this:  def uniq(input):   output = []   for x in input:     if x not in output:       output.append(x)   return output   (Thanks to  for that .)  But I'd like to avail myself of a built-in or a more Pythonic idiom if possible.  Related question:
Which of the following is most correct?      The distance of the shortest path must not be higher than 10km.   The distance of the shortest path must not be greater than 10km.   The distance of the shortest path must not be bigger than 10km.   Or is there an even better word? How to replace ${} placeholders in a text file? I want to pipe the output of a "template" file into MySQL, the file having variables like ${dbName} interspersed. What is the command line utility to replace these instances and dump the output to standard output? Is it possible to turn off the Two-Factor Authentication for an Apple ID? Is it possible to turn off the Two-Factor Authentication for an Apple ID?  I have more than one device linked to this Apple ID and I know the password and security questions. What is special about square numbers here? When or why would you use a right outer join instead of left? states:  "In practice, explicit right outer joins are rarely used, since they can always be replaced with left outer joins and provide no additional functionality."  Can anyone provide a situation where they have preferred to use the RIGHT notation, and why? I can't think of a reason to ever use it. To me, it wouldn't ever make things more clear.  Edit: I'm an Oracle veteran making the New Year's Resolution to wean myself from the (+) syntax. I want to do it right Please anyone tell me when we have to use "has been, have been , had been" and something  started in past and still continuing is it possible to use has been ? Why isn't an infinite direct product of copies of $\Bbb Z$ a free module?   Actually I was asked to show that it's not projective, but as $\Bbb{Z}$ is a PID, so it suffices to show it's not free.   I am stuck here. I saw some questions in SE, but there is no satisfactory answer at all. Using Custom Labels in a Class I have the below If statements using some hard coded strings and I want to make them use as custom labels. I have created custom labels with the same String names as given below. So how can I make these statements to use the Custom Labels I created ?  if(monitoringFrequency == 'daily'){             return dateValue.addDays(1);         }else if(monitoringFrequency == 'weekly'){             return dateValue.addDays(7);         }else if(monitoringFrequency == 'monthly'){             return dateValue.addMonths(1); Which pseudo-$R^2$ measure is the one to report for logistic regression (Cox & Snell or Nagelkerke)? I have SPSS output for a logistic regression model. The output reports two measures for the model fit, Cox &amp; Snell and Nagelkerke.  So as a rule of thumb, which of these $R^²$ measures would you report as the model fit?  Or, which of these fit indices is the one that is usually reported in journals?    Some Background: The regression tries to predict the presence or absence of a bird (capercaillie) from some environmental variables (e.g., steepness, vegetation cover, ...). Unfortunately, the bird did not appear very often (35 hits to 468 misses) so the regression performs rather poorly. Cox &amp; Snell is .09, Nagelkerke, .23.    The subject is environmental sciences or ecology. Paper status changed to “Decision in Process” rapidly after initial submission Proving that a list of perfect square numbers is complete Well, I have a number  $n$ that is given by:  $$n=1+12x^2\left(1+x\right)\tag1$$  I want to find $x\in\mathbb{Z}$ such that $n$ is a perfect square.  I found the following solutions:  $$\left(x,n\right)=\left\{\left(-1,1^2\right),\left(0,1^2\right),\left(1,5^2\right),\left(4,31^2\right),\left(6,55^2\right)\right\}\tag2$$     Is there a way to prove that this a complete set of solutions? So I mean that the solutions given in formula $(2)$ are the only ones?     My work:   We know that: $$ 1 + 12x^2 \left(1+x \right) \ge 0   \space \Longleftrightarrow \space   x \ge -\frac{1+2^{-2/3}+2^{2/3}}{3}   \approx -1.07245 \tag3 $$ So we know that for $x&lt;-1$ there are definitely no solutions. Show that any number of partitions of $2r + k$ into $r + k$ parts is the same for any $k$.   I've tried this, but I haven't come up with anything; hence why I have nothing written here. But in any case, any sort of help is appreciated. Is there any measurable time dilation when Earth reaches perihelion? Can we measure such a phenomena relative to the motion of the outer planets? My Folders Become Hidden System Files And Access Denied? I have an external hard disk , just connected to another system and when i connected to my own computer one of my folders which contain photos become hidden system files AND all folders in it rename to same name !?!? and my access is denied ( Screenshot )    I tried to change ownership but i can't  Any solution !? Why can't I connect to Ubuntu One? I have purchase new laptop from Dell with ubuntu 12.04 preinstalled. while connecting to Ubuntu One following occurs and I am not able to sync with Ubuntu One.   WebClientErr u'Error downloading https://one.ubuntu.com/api/account/ - server replied:Not       Found' u'&lt;!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN"&gt;\n&lt;html&gt; &lt;head&gt;\n&lt;title&gt;404 Not Found&lt;/title&gt;\n&lt;/head&gt;&lt;body&gt;\n&lt;h1&gt; Not Found&lt;/h1&gt;\n&lt;p&gt;The requested URL /api/account/ was not found on this server. &lt;/p&gt;\n&lt;hr&gt;\n&lt;address&gt;Apache/2.2.22 (Ubuntu) Server at one.ubuntu.com Port 443 &lt;/address&gt;\n&lt;/body&gt;&lt;/html&gt;\n' Does Java have buffer overflows? Does Java have buffer overflows? If yes can you give me scenarios? I need to make this equation in LateX but I get some errors when i try to do that.    Can you help me please?? The limit of a sum $\sum_{k=1}^n \frac{n}{n^2+k^2}$ as $n\rightarrow\infty$ Number of possible permutations of n1 1's, n2 2's, n3 3's, n4 4's such that no two adjacent elements are same? Knowing $|z|$ and $|w|$ (and possibly $z\overline{w}$), what are $|z+w|^2$, $|zw|^2$, $|z-w|^2$, $|z/w|^2$? Question 1: Let $z$ and $w$ be complex numbers satisfying $|z| = 4$ and $|w| = 2$. Then enter in the numbers $$ |z+w|^2, |zw|^2, |z-w|^2, \left| \dfrac{z}{w} \right|^2 $$ below, in the order listed above. If any of these cannot be uniquely determined from the information given, enter in a question mark.  I plugged in $4$ and $2$ to each equation and got $36$, $64$, $4$, $4$, for question one. It was wrong.  Question 2: Let $z$ and $w$ be complex numbers satisfying $|z| = 5, |w| = 2,$ and $z\overline{w} = 6+8i.$ Then enter in the numbers $$ |z+w|^2, |zw|^2, |z-w|^2, \left| \dfrac{z}{w} \right|^2 $$ below, in the order listed above. If any of these cannot be uniquely determined from the information given, enter in a question mark.  I don't know how to even start on question 2 because of the $z\overline{w}$.