Combine a list of data frames into one data frame by row
Use bind_rows() from the dplyr package: bind_rows(list_of_dataframes, .id = “column_label”)
list
Get the cartesian product of a series of lists?
itertools.product Available from Python 2.6. import itertools somelists = [ [1, 2, 3], [‘a’, ‘b’], [4, 5] ] for element in itertools.product(*somelists): print(element) Which is the same as, for element in itertools.product([1, 2, 3], [‘a’, ‘b’], [4, 5]): print(element)
ArrayList vs List in C#
Yes, pretty much. List<T> is a generic class. It supports storing values of a specific type without casting to or from object (which would have incurred boxing/unboxing overhead when T is a value type in the ArrayList case). ArrayList simply stores object references. As a generic collection, List<T> implements the generic IEnumerable<T> interface and can … Read more
How to check if an object is a list or tuple (but not string)?
In python 2 only (not python 3): assert not isinstance(lst, basestring) Is actually what you want, otherwise you’ll miss out on a lot of things which act like lists, but aren’t subclasses of list or tuple.
C# LINQ find duplicates in List
The easiest way to solve the problem is to group the elements based on their value, and then pick a representative of the group if there are more than one element in the group. In LINQ, this translates to: var query = lst.GroupBy(x => x) .Where(g => g.Count() > 1) .Select(y => y.Key) .ToList(); If … Read more
List OrderBy Alphabetical Order
If you mean an in-place sort (i.e. the list is updated): people.Sort((x, y) => string.Compare(x.LastName, y.LastName)); If you mean a new list: var newList = people.OrderBy(x=>x.LastName).ToList(); // ToList optional
Find intersection of two nested lists?
You don’t need to define intersection. It’s already a first-class part of set. >>> b1 = [1,2,3,4,5,9,11,15] >>> b2 = [4,5,6,7,8] >>> set(b1).intersection(b2) set([4, 5])
How can I add an item to a IEnumerable collection?
You cannot, because IEnumerable<T> does not necessarily represent a collection to which items can be added. In fact, it does not necessarily represent a collection at all! For example: IEnumerable<string> ReadLines() { string s; do { s = Console.ReadLine(); yield return s; } while (!string.IsNullOrEmpty(s)); } IEnumerable<string> lines = ReadLines(); lines.Add(“foo”) // so what is … Read more
Remove all occurrences of a value from a list?
Functional approach: Python 3.x >>> x = [1,2,3,2,2,2,3,4] >>> list(filter((2).__ne__, x)) [1, 3, 3, 4] or >>> x = [1,2,3,2,2,2,3,4] >>> list(filter(lambda a: a != 2, x)) [1, 3, 3, 4] Python 2.x >>> x = [1,2,3,2,2,2,3,4] >>> filter(lambda a: a != 2, x) [1, 3, 3, 4]
Print a list in reverse order with range()?
use reversed() function: reversed(range(10)) It’s much more meaningful. Update: If you want it to be a list (as btk pointed out): list(reversed(range(10))) Update: If you want to use only range to achieve the same result, you can use all its parameters. range(start, stop, step) For example, to generate a list [5,4,3,2,1,0], you can use the … Read more