The Wolfram Language encapsulates in a small number of functions vast flexibility in rearranging lists with any structure and any number of elements.

Flatten — flatten out any sequence of levels in a nested list

Partition — partition lists or nested lists into sublists

Join — join lists together at any level

Catenate — catenate elements from a list of lists

ArrayFlatten  ▪  ArrayReshape  ▪  FlattenAt  ▪  Splice  ▪  Nothing

TakeList — take a succession of sublists from a list

Sort — sort lexicographically or with any comparison function

ReverseSort — sort reverse lexicographically

SortBy — sort by the values of a function applied to elements

AlphabeticSort  ▪  NumericalSort  ▪  LexicographicSort  ▪  ReverseSortBy

Reverse — reverse a list at any level

RotateLeft, RotateRight — cyclically rotate lists at any depth

Transpose — transpose any collection of levels

ArrayReduce — reduce dimensions of an array by applying a function

ArrayResample — resample an array to higher or lower resolution

ArrayPad — add padding on each side

ArrayFilter — filter an array using local neighborhoods

Riffle — intersperse additional elements

PadLeft, PadRight — pad lists to be a particular length at any depth

Split — split into runs of identical elements

Gather — gather sublists of identical elements

Union, Tally — enumerate, tally all distinct elements in a list

DeleteDuplicates — delete duplicate elements in a list

DeleteDuplicatesBy — delete elements for which values of a function are duplicated

DeleteAdjacentDuplicates — delete duplicates adjacent to one another

SplitBy, GatherBy — split, gather based on values of a function applied to elements

Tuples  ▪  Subsets  ▪  Subsequences  ▪  Permutations  ▪  RandomSample

Groupings — generate all possible groupings of a list into sublists

Union  ▪  Intersection  ▪  Complement

Sequence-Oriented Operations

SequenceSplit — split a list at sequences matching a pattern

SequenceReplace — replace sequences in a list

Element-Oriented Operations »

ReplacePart  ▪  Take  ▪  Drop  ▪  Append  ▪  AppendTo