list

How can I tell if a set of parens in Perl code will act as grouping parens or form a list?

In perl, parentheses are used for overriding precedence (as in most programming languages) as well as for creating lists. How can I tell if a particular pair of parens will be treated as a grouping construct or a one-element list? For example, I'm pretty sure this is a scalar and not a one-element list: (1 + 1) But what about more compl...

What's wrong with my destructor?

// Sparse Array Assignment.cpp : Defines the entry point for the console application. // #include "stdafx.h" #include<iostream> using namespace std; struct node{ int row; int col; int value; node* next_in_row; node* next_in_col; }; class MultiLinkedListSparseArray { private: char *logf...

Should I Prefer a Closed or Open List<> System?

Hey guys, I've got a class in my project that stores a List<> of elements. I'm trying to figure out whether I should allow the user to add to that List directly (e.g. Calling the native add/remove methods) or lock it down by declaring the List private and only allowing a handful of methods I choose to actually alter the List. It's a fr...

Dictionary with Exact Same Keys and Values

Hi All I need something like a Dictionary or a SortedList but i keep getting exceptions thrown when it receives two things that are the same... Is there another way around this? Thanks ...

F# insert/remove item from list

How should I go about removing a given element from a list? As an example, say I have list ['A'; 'B'; 'C'; 'D'; 'E'] and want to remove the element at index 2 to produce the list ['A'; 'B'; 'D'; 'E']? I've already written the following code which accomplishes the task, but it seems rather inefficient to traverse the start of the list whe...

Mutation Problem - Clojure

having trouble changing an element of my function represented as a list. code for random function: (defn makerandomtree-10 [pc maxdepth maxwidth fpx ppx] (if-let [output (if (and (< (rand) fpx) (> maxdepth 0)) (let [head (nth operations (rand-int (count operations))) children (doall (loop[function (list) width...

Take the intersection of an arbitrary number of lists in python

Suppose I have a list of lists of elements which are all the same (i'll use ints in this example) [range(100)[::4], range(100)[::3], range(100)[::2], range(100)[::1]] What would be a nice and/or efficient way to take the intersection of these lists (so you would get every element that is in each of the lists)? For the example that wou...

Matching tuples in Prolog

Why does Prolog match (X, Xs) with a tuple containing more elements? An example: test2((X, Xs)) :- write(X), nl, test2(Xs). test2((X)) :- write(X), nl. test :- read(W), ...

Most efficient way to update attribute of one instance

Hi all - I'm creating an arbitrary number of instances (using for loops and ranges). At some event in the future, I need to change an attribute for only one of the instances. What's the best way to do this? Right now, I'm doing the following: 1) Manage the instances in a list. 2) Iterate through the list to find a key value. 3) Once I ...

Removing Item From List - during iteration - what's wrong with this idiom ?

As an experiment, I did this: letters=['a','b','c','d','e','f','g','h','i','j','k','l'] for i in letters: letters.remove(i) print letters The last print shows that not all items were removed ? (every other was). IDLE 2.6.2 >>> ================================ RESTART ================================ >>> ['b', 'd', 'f', 'h'...

Counting positive elements in a list with Python list comprehensions

I have a list of integers and I need to count how many of them are > 0. I'm currently doing it with a list comprehension that looks like this: sum([1 for x in frequencies if x > 0]) It seems like a decent comprehension but I don't really like the "1"; it seems like a bit of a magic number. Is there a more Pythonish way to do this? ...

Quickest and most efficient method to search top 3 numbers?

I currently have an array of around 8 - 10 numbers that changes on a periodic basis. So around every 5 - 10 seconds the numbers get updated. I need to get the top 3 numbers in the array every 10 seconds. This is all done on a mobile device. The array is the RSSI of the currently scanned access points, so in my office its usually arou...

Strange things appear on running the program

Hey! I'm fixing a program but I'm facing a problem and I cant really realize what's the wrong on the code. I would appreciate any help. I didnt post all the code...but i think with this part you can get an idea of it. With the following function enter() I wanna add user commands' datas to a list. eg. user give the command: "en james b...

just-in-time list

I'd like to know if there is a class available, either in the standard library or in pypi, that fits this description. The constructor would take an iterator. It would implement the container protocol (ie _getitem_, _len_, etc), so that slices, length, etc., would work. In doing so, it would iterate and retain just enough values from ...

What is a better, cleaner way of using List<T>

I'm looking to implement a few nicer ways to use List in a couple of apps I'm working on. My current implementation looks like this. MyPage.aspx.cs protected void Page_Load(object sender, EventArgs e) { BLL.PostCollection oPost = new BLL.PostCollection(); oPost.OpenRecent(); rptPosts.DataSource = oArt; rptPosts.DataBi...

Deleting first and last element of a linked list in C

struct person { int age; char name[100]; struct person *next; }; void delfirst(struct person **p)// For deleting the beginning { struct person *tmp,*m; m = (*p); tmp = (*p)->next; free(m); return; } void delend(struct person **p)// For deleting the end { struct person *tmp,*m; tmp=*p; w...

How to display List<> using ListView?

When I use ListView to display a array of my object, I can use the following code: MyObject[] myObject; ... ArrayAdapter<MyObject> itemList = new ArrayAdapter<MyObject>(this, R.layout.list, myObject); setListAdapter(itemList); In case that the input is a list: List<MyObject> myobject; How can I assign it to ListAdapter? Please...

Python adding elements from string

I have a string like this "1 1 3 2 1 1 1 2 1 1 1 1 1 1 1 1,5 0,33 0,66 1 0,33 0,66 1 1 2 1 1 2 1 1 2 0,5 0,66 2 1 2 1 1 1 0 1". How to add elements to each other in python ? ...

Erlang : flattening a list of strings

I have a list like this: [["str1","str2"],["str3","str4"],["str5","str6"]] And I need to convert it to ["str1", "str2", "str3", "str4", "str5", "str6"] How do I do this? The problem is that I'm dealing with lists of strings, so when I do lists:flatten([["str1","str2"],["str3","str4"],["str5","str6"]]) I get "str1str2str3str4...

Creating a Generic List of a specified type

Hi I want to create a generic list - but I want to specify the type at runtime - is there a way I can do this? using reflection perhaps? Something like this... Public Shared Sub create(ByVal t As Type) Dim myList As New Generic.List(Of t) End Sub Thanks in advance James ...