I don't remember whether I was dreaming or not but I seem to recall there being a function which allowed something like, foo in iter_attr(array of python objects, attribute name) I've looked over the docs but this kind of thing doesn't fall under any obvious listed headers...
I haven't been able to find an understandable explanation of how to actually use Python's itertools.groupby() function. What I'm trying to do is this: take a list - in this case, the children of an objectified lxml element - divide it into groups based on some criteria, and then later iterate over each of these groups separately. I've...
If I have a Perl hash with a bunch of (key, value) pairs, what is the preferred method of iterating through all the keys? I have heard that using each may in some way have unintended side effects. So, is that true, and is one of the two following methods best, or is there a better way? # Method 1 while (my ($key, $value) = each(%hash)...
I am trying to find a generic way of accessing a set of containers. I have a standard vector and list in addition to another custom list. The custom list defines an iterator; class Iterator: public std::iterator<std::forward_iterator_tag, T> { // ... } Iterator begin() { return (Iterator(root)); } Iterator end() { return ...
I love list comprehensions in Python, because they concisely represent a transformation of a list. However, in other languages, I frequently find myself writing something along the lines of: foreach (int x in intArray) if (x > 3) //generic condition on x x++ //do other processing This example is in C#, where I'm under the ...
It seems like if you want to get the keys of a mapping, you ask for them; otherwise, give me the whole mapping (constituted by a set of key-value pairs). Is there a historical reason for this? ...
I have a function that gets x(a value) and xs(a list) and removes all values that are bigger than x from the list. Well it doesn't work, can you tell me why? (defun biggerElems(x xs) (let ((xst)) (dolist (elem xs) (if (> x elem) (setf xst (remove elem xs)))) xst)) ...
If I have an object implementing the Map interface in Java and I wish to iterate over every pair contained within it, what is the most efficient way of going through the map? Will the ordering of elements depend on the specific map implementation that I have for the interface? ...
I'm returning to c++ after being away for a bit and trying to dust off the old melon. In Java Iterator is an interface to a container having methods: hasNext(), next() and remove(). The presence of hasNext() means it has the concept of a limit for the container being traversed. //with an Iterator Iterator<String> iter = trees.iterator...
Lets say I have a Dictionary object: Dictionary myDictionary<int, SomeObject> = new Dictionary<string, SomeObject>(); Now I want to iterate through the dictionary in reverse order. I can't use a simple for loop because I don't know the keys of the dictionary. A foreach is easy: foreach (SomeObject object in myDictionary.Values) { ...
I have an IList that contains items ( parent first ), they need to be added to a Diagram Document in the reverse order so that the parent is added last, drawn on top so that it is the first thing to be selected by the user. What's the best way to do it? Something better/more elegant than what I am doing currently which I post below.. ...
In Python there is a really neat function called zip which can be used to iterate through two lists at the same time: list1 = [1, 2, 3] list2 = ["a", "b", "c"] for v1, v2 in zip(list1, list2): print v1 + " " + v2 The above code shoul produce the following: 1 a 2 b 3 c I wonder if there is a method like it available in .Net? I'm ...
I have some code which collects points (consed integers) from a loop which looks something like this: (loop for x from 1 to 100 for y from 100 downto 1 collect `(,x . ,y)) My question is, is it correct to use `(,x . ,y) in this situation? Edit: This sample is not about generating a table of 100x100 items, the co...
Do you think that project iteration length is related to project team size? If so, how? What other key factors do you use to recognize correct iteration length for different projects? ...
I've used recursion quite a lot on my many years of programming to solve simple problems, but I'm fully aware that sometimes you need iteration due to memory/speed problems. So, sometime in the very far past I went to try and find if there existed any "pattern" or text-book way of transforming a common recursion approach to iteration an...
Which is generally fastest when reading/comparing row info from a DataTable? 'assume dt as datatable' 'method 1' dim i as int32 for i = 0 to dt.rows.count - 1 .... next 'method 2' dim row as datarow for each row in dt.rows .... next And if there's a difference, in what circumstances does it pay to use one over the other? Th...
Typically you will find STL code like this: for (SomeClass::SomeContainer::iterator Iter = m_SomeMemberContainerVar.begin(); Iter != m_SomeMemberContainerVar.end(); ++Iter) { } But we actually have the recommendation to write it like this: SomeClass::SomeContainer::iterator Iter = m_SomeMemberContainerVar.begin(); SomeClass::SomeCont...
StringTokenizer? Convert the String to a char[] and iterate over that? Something else? ...
I was just writing some quick code and noticed this complier error Using the iteration variable in a lambda expression may have unexpected results. Instead, create a local variable within the loop and assign it the value of the iteration variable. I know what it means and I can easily fix it, not a big deal. But I was wondering why ...
Given this algorithm, I would like to know if there exists an iterative version. Also, I want to know if the iterative version can be faster. This some kind of pseudo-python... the algorithm returns a reference to root of the tree make_tree(array a) if len(a) == 0 return None; node = pick a random point from the array c...