Popular recipes tagged "functional" but not "recursion"

fmap(): a kind of inverse of the built-in Python map() function (Python)

2012-10-06T22:15:17-07:00

Python recipe 578281 by Vasudev Ram (composition, fmap, functional, map).

The Python map() function returns a list of the results of applying the function to the items of the argument sequence(s).

The fmap() function does the inverse, in a sense. It returns the result of applying a list of functions to a given argument.

Recursively defined, Haskell-style infinite lists (Python)

2012-05-04T14:09:14-07:00

Python recipe 578119 by John Crichton (decorator, functional, generator, infinite, itertools, lazy, recursive). Revision 2.

A decorator to simplify the creation of recursively defined, Haskell-style infinite lists -- ie. recursive generators -- inspired by Raymond Hettinger's "Technique for cyclical iteration" [*].

[*] http://code.activestate.com/recipes/576961-technique-for-cyclical-iteration/

Dirt simple map/reduce (Python)

2011-05-15T16:46:55-07:00

Python recipe 577676 by Raymond Hettinger (analysis, crosstab, functional, map_reduce, pivot_table, statistics). Revision 9.

Simple tool for analyzing datasets.

indefinite currying decorator with greedy call and up front args checking (Python)

2011-10-28T22:05:55-07:00

Python recipe 577928 by Przemyslaw Podczasi (curry, decorator, functional). Revision 2.

Decorator makes function currying as long as there are more correct arguments to take and fires it as soon as there is enough to call, also checks arguments up front for errors.

Binary search function. (Python)

2011-02-07T06:37:52-08:00

Python recipe 577565 by Kevin L. Sitze (binary, binary_search, bsearch, functional, lower_bound, optimal_solution, search, upper_bound). Revision 3.

For a number of years Python has provided developers with the special parameters 'cmp' and 'key' on list.sort and __builtin__.sorted. However Python does not provide a built-in mechanism for doing binary searches on such sorted lists. This recipe provides a simple function that allows you to perform binary searches on your sorted sequences.

Python Infinite Rotations and Tails (Python)

2011-02-13T15:27:42-08:00

Python recipe 577574 by Thomas Ahle (cycles, functional, infinite, lists, rotations, tails).

This is an example of how functional ideas of infinite lists can be used in python to optimize memory usage of certain problems.

Functional selection sort (Python)

2009-09-29T13:34:35-07:00

Python recipe 576917 by pavel (algorithm, algorithms, functional, lambda, reduce, selection, sort, sorting). Revision 3.

This is a variant of selection sort without using for-statements. Do you like it? :-)

compare(), making filter() fun again (Python)

2008-10-04T12:40:42-07:00

Python recipe 576526 by Andreas Nilsson (compare, filter, functional, lambda). Revision 2.

compare() takes a function parameter and returns a callable comparator when compared to a value. When called, the comparator returns result of comparing the result of calling the function and the value it was created with.

Basic usage:

items = [1, 2, 3, 4, 5]

def double(x):
    return x * 2

for i in filter(compare(double) > 5, items):
    print i #Prints 3, 4 and 5