ReverseSortBy
ReverseSortBy[list,f]
sorts the elements of list using the reverse canonical order defined by applying f to each of them.
ReverseSortBy[list,f,p]
sorts the elements of list using the function p to compare pairs of results of applying f to each element.
represents an operator form of ReverseSortBy that can be applied to an expression.
Details
- ReverseSortBy[{e1,e2,e3,…},f] sorts the ei so that the f[ei] lie in reverse canonical order.
- If some of the f[ei] are the same, then the reverse canonical order of the corresponding ei is used.
- ReverseSortBy[list,f] is equivalent to reversing the result of SortBy[list,f].
- In the result of ReverseSortBy[{e1,e2,e3,…},f,p], element ei will be sorted before ej if p[f[ei],f[ej]] is -1 or False.
- ReverseSortBy[list,{f1,f2,…}] breaks ties by successively using the values obtained from the fi.
- ReverseSortBy can be used on expressions with any head, not only List.
- ReverseSortBy[f][list] is equivalent to ReverseSortBy[list,f].
Examples
open allclose allBasic Examples (5)
Reverse sort a list of lists by the last element of each sublist:
Reverse sort by the total of each sublist:
Reverse sort a list of integers by their values modulo 3:
Reverse sort elements of an Association by their values modulo 3:
Use ReverseSortBy as an operator form:
Scope (5)
Reverse sort by numerical value:
The default reverse order ranks these symbolically:
Reverse sort by absolute numerical value:
Reverse sort by Re, Im, Arg and Abs:
Reverse sort dates by converting to their absolute time form:
Reverse sort complex numbers by their modulus using numerical order:
Using canonical order gives a different result:
Reverse sort by string length:
Reverse sort the strings using Greater as the ordering function:
Generalizations & Extensions (1)
ReverseSortBy can be used on expressions with any head:
Applications (1)
Reverse sort mathematically equivalent expressions by different criteria:
Reverse sort by LeafCount:
Reverse sort by size of error for numerical evaluation with machine numbers at :
Properties & Relations (1)
ReverseSortBy[list,f] is equivalent to Reverse[SortBy[list,f]], even in the presence of ties:
Use ReverseSortBy[list,{f}] to avoid reordering ties:
Text
Wolfram Research (2019), ReverseSortBy, Wolfram Language function, https://reference.wolfram.com/language/ref/ReverseSortBy.html.
CMS
Wolfram Language. 2019. "ReverseSortBy." Wolfram Language & System Documentation Center. Wolfram Research. https://reference.wolfram.com/language/ref/ReverseSortBy.html.
APA
Wolfram Language. (2019). ReverseSortBy. Wolfram Language & System Documentation Center. Retrieved from https://reference.wolfram.com/language/ref/ReverseSortBy.html