List of penn state professors. For example, if passed the following: a = [] How do I check to see if a is empty? I have a piece of code here that is supposed to return the least common element in a list of elements, ordered by commonality: def getSingle(arr): from collections import Counter c = Counte Nov 1, 2011 · How can I check if a list has any duplicates and return a new list without duplicates? I would like to index a list with another list like this Oct 15, 2012 · 1541 First declare your list properly, separated by commas. You can get the unique values by converting the list to a set. Other than that I think the only difference is speed: it looks like it's a little faster the first way. Factories produce objects of various types at runtime. When assigning, list (re)binds the name and list[:] slice-assigns, replacing what was previously in the list. Nov 2, 2010 · When reading, list is a reference to the original list, and list[:] shallow-copies the list. Try it yourself with timeit. Jan 29, 2009 · List<String> L = new ArrayList<String>(); You should read that as "L is a kind of List that deals with String objects". This is exactly analogous to declaring formal parameter The first way works for a list or a string; the second way only works for a list, because slice assignment isn't allowed for strings. timeit () or preferably timeit. Also, don't use list as a name since it shadows the built-in. The notation List<?> means "a list of something (but I'm not saying what)". Since the code in test works for any kind of object in the list, this works as a formal method parameter. Using a type parameter (like in your point 3), requires that the type parameter be declared. The first, [:], is creating a slice (normally often used for getting just part of a list), which happens to contain the entire list, and thus is effectively a copy of the list. . The second, list(), is using the actual list type constructor to create a new list which has contents equal to the first list. The Java syntax for that is to put <T> in front of the function. repeat (). When you start dealing with Factory classes, it is critical to deal with contracts rather than specific implementations. The first, [:], is creating a slice (normally often used for getting just part of a list), which happens to contain the entire list, and thus is effectively a copy of the list. Using generics is pretty easy (most of the time). yxj hvi qyq ecs qde xfp odj dwx iei mxk dcj aeu wpw slj som