ReverseSort
ReverseSort[list]
sorts the elements of list into reverse canonical order.
ReverseSort[list,p]
sorts using the ordering function p.
Details
- ReverseSort by default orders integers and rational and approximate real numbers by their numerical values, sorting from largest to smallest.
- ReverseSort gives the same result as reversing Sort except it does not reverse ties.
- ReverseSort[list,p] applies the function p to pairs of elements in list to determine whether they are in order. The default function p is Order.
- ReverseSort can be used on expressions with any head, not only List.
Examples
open all close allBasic Examples (2)
Scope (9)
Input Data (5)
Sort a list of integers in reverse order:
ReverseSort[{0, 11, 13, 4, 9}]Reverse-sort an expression with any head:
ReverseSort[head[x, z, y, t]]ReverseSort works with associations:
ReverseSort[<|a -> 4, b -> 1, c -> 3, d -> 2, e -> 2|>]Reverse-sort the rows of a Tabular object by the values of the first column:
Tabular[{{1, 4}, {3, 2}, {2, -3}}, {"a", "b"}]ReverseSort[%]Reverse-sort the rows of a Dataset object by their first element:
Dataset[{<|"a" -> 1, "b" -> 4|>, <|"a" -> 3, "b" -> 2|>, <|"a" -> 2, "b" -> -3|>}]ReverseSort[%]Ordering Functions (4)
Use an ordering function as second argument:
ReverseSort[{0, 11, 13, 4, 9}, Greater]Use a pure function as ordering function:
ReverseSort[{c, b, d, a}, OrderedQ[{#1, #2}]&]Use NumericalOrder to allow complex numbers and number-like expressions:
ReverseSort[{1 + I, 3, 2 - I}, NumericalOrder]ReverseSort[{Yesterday, Tomorrow, Today}, NumericalOrder]Sort according to the rules of a particular language with AlphabeticOrder:
words = {"čeština", "hebrejčina", "hebrejčina", "chorvátčina"};ReverseSort[words, AlphabeticOrder["Slovak"]]ReverseSort[words, AlphabeticOrder["Serbian"]]Define a custom ordering function that puts symbols after numbers with ReverseSort:
p[_ ? NumberQ, _Symbol] := -1
p[_Symbol, _ ? NumberQ] := 1
p[_Symbol, _Symbol] := 0
p[x_ ? NumberQ, y_ ? NumberQ] := x ≤ yReverseSort[{x, 1, z, 5, a, 2, e}, p]Properties & Relations (4)
ReverseSort gives the same result as reversing Sort except it does not reverse ties:
list = {x, z, y}ReverseSort[list]% === Reverse[Sort[list]]NumericalOrder treats 3 and 3.`10 as a tie:
NumericalOrder[3, 3.`10]Both ReverseSort and Sort do not reorder ties:
list = {2, 3, 3.`10, 5};list1 = ReverseSort[list, NumericalOrder]list2 = Sort[list, NumericalOrder]Therefore, those two results are not the reverse of one another:
list1 === Reverse[list2]ReverseSort with an ordering function p is equivalent to Sort with the reverse ordering function:
list = {2, 3, 3.`10, 5};The reverse ordering for LessEqual is provided by Greater:
Not[LessEqual[a, b]]Sort[list, LessEqual]ReverseSort[list, Greater]For ordering functions returning -1, 0, 1, the reverse ordering is obtained composing with Minus:
list = {"B", "D", "A", "C"};Sort[list, AlphabeticOrder[]]ReverseSort[list, Composition[Minus, AlphabeticOrder]]ReverseSort orders a list of pairs of numbers by decreasing the first element:
pairs = RandomInteger[10, {5, 2}]ReverseSort[pairs]Use ReverseSortBy to select which element is sorted in decreasing order:
ReverseSortBy[pairs, First]ReverseSortBy[pairs, Last]Text
Wolfram Research (2017), ReverseSort, Wolfram Language function, https://reference.wolfram.com/language/ref/ReverseSort.html.
CMS
Wolfram Language. 2017. "ReverseSort." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/ReverseSort.html.
APA
Wolfram Language. (2017). ReverseSort. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ReverseSort.html