WolframLang: Misc List Operations
Check Existence
Get the Position of a Element
Position[expr, pattern]
-
Return a list of positions that
Pattern
occur in expression.
If not exist, return a empty list.
xx = {a, {{b, c}, a}, e}; (* position of e is {3} *) Position[ xx, e ] === {{3}} (* position of a is {1} and {2, 2} *) Position[ xx, a ] === {{1}, {2, 2}} (* when not found, empty list *) Position[ xx, m ] === {} (* position of b *) Position[ xx, b ] === {{2, 1, 1}} (* position of {b, c} *) Position[ xx, {b, c} ] === {{2, 1}}
Group into Sublists
Partition
-
group every n items into sublist.
x = Range[ 8 ]; Partition[ x, 2 ] === {{1, 2}, {3, 4}, {5, 6}, {7, 8}}
order
Ordering
-
return a list of integers that represent the ordering of the items.
Ordering[ {a, c, b} ] === {1, 3, 2}
RotateRight
-
shift all elements to the right, last item is moved to first.
RotateRight[ {1, 2, 3, 4} ] === {4, 1, 2, 3}
RotateLeft
- shift all elements to the left, first item is moved to last.
Other Functions on List
Join
- concatenate lists Join
Union
- union of sets Union
Intersection
- intersection of sets Intersection
Complement
- subtract a set from other sets Complement
Subsets
- all possible subsets Subsets
Riffle
- Riffle
Partition
- Partition
Split
- Split
SplitBy
- SplitBy
Gather
- Gather
GatherBy
- GatherBy
Tuples
- Tuples
Permutations
- Permutations
Min
- Min
Max
- Max
Flatten
- Flatten
Transpose
- Transpose
PadLeft
- PadLeft