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lists(3erl) | Erlang Module Definition | lists(3erl) |
NAME¶
lists - List Processing FunctionsDESCRIPTION¶
This module contains functions for list processing. Unless otherwise stated, all functions assume that position numbering starts at 1. That is, the first element of a list is at position 1. Two terms T1 and T2 compare equal if T1 == T2 evaluates to true. They match if T1 =:= T2 evaluates to true. Whenever an ordering function F is expected as argument, it is assumed that the following properties hold of F for all x, y and z:- *
- if x F y and y F x then x = y (F is antisymmetric);
- *
- if x F y and y F z then x F z (F is transitive);
- *
- x F y or y F x (F is total).
EXPORTS¶
all(Pred, List) -> boolean()
Types:
Pred = fun((Elem :: T) -> boolean())
List = [T]
T = term()
Returns true if Pred(Elem) returns true for all elements
Elem in List, otherwise false.
any(Pred, List) -> boolean()
Types:
Pred = fun((Elem :: T) -> boolean())
List = [T]
T = term()
Returns true if Pred(Elem) returns true for at least one
element Elem in List.
append(ListOfLists) -> List1
Types:
ListOfLists = [List]
List = List1 = [T]
T = term()
Returns a list in which all the sub-lists of ListOfLists have been
appended. For example:
> lists:append([[1, 2, 3], [a, b], [4, 5, 6]]). [1,2,3,a,b,4,5,6]
append(List1, List2) -> List3
Types:
List1 = List2 = List3 = [T]
T = term()
Returns a new list List3 which is made from the elements of List1
followed by the elements of List2. For example:
> lists:append("abc", "def"). "abcdef"lists:append(A, B) is equivalent to A ++ B.
concat(Things) -> string()
Types:
Things = [Thing]
Thing = atom() | integer() | float() | string()
Concatenates the text representation of the elements of Things. The
elements of Things can be atoms, integers, floats or strings.
> lists:concat([doc, '/', file, '.', 3]). "doc/file.3"
delete(Elem, List1) -> List2
Types:
Elem = T
List1 = List2 = [T]
T = term()
Returns a copy of List1 where the first element matching Elem is
deleted, if there is such an element.
droplast(List) -> InitList
Types:
List = [T, ...]
InitList = [T]
T = term()
Drops the last element of a List. The list should be non-empty, otherwise
the function will crash with a function_clause
dropwhile(Pred, List1) -> List2
Types:
Pred = fun((Elem :: T) -> boolean())
List1 = List2 = [T]
T = term()
Drops elements Elem from List1 while Pred(Elem) returns
true and returns the remaining list.
duplicate(N, Elem) -> List
Types:
N = integer() >= 0
Elem = T
List = [T]
T = term()
Returns a list which contains N copies of the term Elem. For
example:
> lists:duplicate(5, xx). [xx,xx,xx,xx,xx]
filter(Pred, List1) -> List2
Types:
Pred = fun((Elem :: T) -> boolean())
List1 = List2 = [T]
T = term()
List2 is a list of all elements Elem in List1 for which
Pred(Elem) returns true.
filtermap(Fun, List1) -> List2
Types:
Fun = fun((Elem) -> boolean() | {true, Value})
List1 = [Elem]
List2 = [Elem | Value]
Elem = Value = term()
Calls Fun(Elem) on successive elements Elem of List1.
Fun/2 must return either a boolean or a tuple {true, Value}. The
function returns the list of elements for which Fun returns a new
value, where a value of true is synonymous with {true, Elem}.
That is, filtermap behaves as if it had been defined as follows:
filtermap(Fun, List1) -> lists:foldr(fun(Elem, Acc) -> case Fun(Elem) of false -> Acc; true -> [Elem|Acc]; {true,Value} -> [Value|Acc] end, end, [], List1).Example:
> lists:filtermap(fun(X) -> case X rem 2 of 0 -> {true, X div 2}; _ -> false end end, [1,2,3,4,5]). [1,2]
flatlength(DeepList) -> integer() >= 0
Types:
DeepList = [term() | DeepList]
Equivalent to length(flatten(DeepList)), but more efficient.
flatmap(Fun, List1) -> List2
Types:
Fun = fun((A) -> [B])
List1 = [A]
List2 = [B]
A = B = term()
Takes a function from As to lists of Bs, and a list of As
(List1) and produces a list of Bs by applying the function to
every element in List1 and appending the resulting lists.
That is, flatmap behaves as if it had been defined as follows:
flatmap(Fun, List1) -> append(map(Fun, List1)).Example:
> lists:flatmap(fun(X)->[X,X] end, [a,b,c]). [a,a,b,b,c,c]
flatten(DeepList) -> List
Types:
DeepList = [term() | DeepList]
List = [term()]
Returns a flattened version of DeepList.
flatten(DeepList, Tail) -> List
Types:
DeepList = [term() | DeepList]
Tail = List = [term()]
Returns a flattened version of DeepList with the tail Tail
appended.
foldl(Fun, Acc0, List) -> Acc1
Types:
Fun = fun((Elem :: T, AccIn) -> AccOut)
Acc0 = Acc1 = AccIn = AccOut = term()
List = [T]
T = term()
Calls Fun(Elem, AccIn) on successive elements A of List,
starting with AccIn == Acc0. Fun/2 must return a new accumulator
which is passed to the next call. The function returns the final value of the
accumulator. Acc0 is returned if the list is empty. For example:
> lists:foldl(fun(X, Sum) -> X + Sum end, 0, [1,2,3,4,5]). 15 > lists:foldl(fun(X, Prod) -> X * Prod end, 1, [1,2,3,4,5]). 120
foldr(Fun, Acc0, List) -> Acc1
Types:
Fun = fun((Elem :: T, AccIn) -> AccOut)
Acc0 = Acc1 = AccIn = AccOut = term()
List = [T]
T = term()
Like foldl/3, but the list is traversed from right to left. For example:
> P = fun(A, AccIn) -> io:format("~p ", [A]), AccIn end. #Fun<erl_eval.12.2225172> > lists:foldl(P, void, [1,2,3]). 1 2 3 void > lists:foldr(P, void, [1,2,3]). 3 2 1 voidfoldl/3 is tail recursive and would usually be preferred to foldr/3.
foreach(Fun, List) -> ok
Types:
Fun = fun((Elem :: T) -> term())
List = [T]
T = term()
Calls Fun(Elem) for each element Elem in List. This
function is used for its side effects and the evaluation order is defined to
be the same as the order of the elements in the list.
keydelete(Key, N, TupleList1) -> TupleList2
Types:
Key = term()
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = TupleList2 = [Tuple]
Returns a copy of TupleList1 where the first occurrence of a tuple whose
Nth element compares equal to Key is deleted, if there is such a
tuple.
keyfind(Key, N, TupleList) -> Tuple | false
Types:
Key = term()
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList = [Tuple]
Searches the list of tuples TupleList for a tuple whose Nth
element compares equal to Key. Returns Tuple if such a tuple is
found, otherwise false.
keymap(Fun, N, TupleList1) -> TupleList2
Types:
Fun = fun((Term1 :: term()) -> Term2 :: term())
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = TupleList2 = [Tuple]
Returns a list of tuples where, for each tuple in TupleList1, the
Nth element Term1 of the tuple has been replaced with the result
of calling Fun(Term1).
Examples:
> Fun = fun(Atom) -> atom_to_list(Atom) end. #Fun<erl_eval.6.10732646> 2> lists:keymap(Fun, 2, [{name,jane,22},{name,lizzie,20},{name,lydia,15}]). [{name,"jane",22},{name,"lizzie",20},{name,"lydia",15}]
keymember(Key, N, TupleList) -> boolean()
Types:
Key = term()
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList = [Tuple]
Returns true if there is a tuple in TupleList whose Nth
element compares equal to Key, otherwise false.
keymerge(N, TupleList1, TupleList2) -> TupleList3
Types:
N = integer() >= 1
TupleList2 = [T2]
TupleList3 = [(T1 | T2)]
T1 = T2 = Tuple
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = [T1]
Returns the sorted list formed by merging TupleList1 and
TupleList2. The merge is performed on the Nth element of each
tuple. Both TupleList1 and TupleList2 must be key-sorted prior
to evaluating this function. When two tuples compare equal, the tuple from
TupleList1 is picked before the tuple from TupleList2.
keyreplace(Key, N, TupleList1, NewTuple) -> TupleList2
Types:
Key = term()
N = integer() >= 1
NewTuple = Tuple
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = TupleList2 = [Tuple]
Returns a copy of TupleList1 where the first occurrence of a T
tuple whose Nth element compares equal to Key is replaced with
NewTuple, if there is such a tuple T.
keysearch(Key, N, TupleList) -> {value, Tuple} | false
Types:
Key = term()
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList = [Tuple]
Searches the list of tuples TupleList for a tuple whose Nth
element compares equal to Key. Returns {value, Tuple} if such a
tuple is found, otherwise false.
Note:
This function is retained for backward compatibility. The function
lists:keyfind/3 (introduced in R13A) is in most cases more convenient.
keysort(N, TupleList1) -> TupleList2
Types:
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = TupleList2 = [Tuple]
Returns a list containing the sorted elements of the list TupleList1.
Sorting is performed on the Nth element of the tuples. The sort is
stable.
keystore(Key, N, TupleList1, NewTuple) -> TupleList2
Types:
Key = term()
N = integer() >= 1
TupleList2 = [Tuple, ...]
NewTuple = Tuple
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = [Tuple]
Returns a copy of TupleList1 where the first occurrence of a tuple
T whose Nth element compares equal to Key is replaced
with NewTuple, if there is such a tuple T. If there is no such
tuple T a copy of TupleList1 where [NewTuple] has been
appended to the end is returned.
keytake(Key, N, TupleList1) -> {value, Tuple, TupleList2} | false
Types:
Key = term()
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = TupleList2 = [tuple()]
Searches the list of tuples TupleList1 for a tuple whose Nth
element compares equal to Key. Returns {value, Tuple,
TupleList2} if such a tuple is found, otherwise false.
TupleList2 is a copy of TupleList1 where the first occurrence of
Tuple has been removed.
last(List) -> Last
Types:
List = [T, ...]
Last = T
T = term()
Returns the last element in List.
map(Fun, List1) -> List2
Types:
Fun = fun((A) -> B)
List1 = [A]
List2 = [B]
A = B = term()
Takes a function from As to Bs, and a list of As and
produces a list of Bs by applying the function to every element in the
list. This function is used to obtain the return values. The evaluation order
is implementation dependent.
mapfoldl(Fun, Acc0, List1) -> {List2, Acc1}
Types:
Fun = fun((A, AccIn) -> {B, AccOut})
Acc0 = Acc1 = AccIn = AccOut = term()
List1 = [A]
List2 = [B]
A = B = term()
mapfoldl combines the operations of map/2 and foldl/3 into
one pass. An example, summing the elements in a list and double them at the
same time:
> lists:mapfoldl(fun(X, Sum) -> {2*X, X+Sum} end, 0, [1,2,3,4,5]). {[2,4,6,8,10],15}
mapfoldr(Fun, Acc0, List1) -> {List2, Acc1}
Types:
Fun = fun((A, AccIn) -> {B, AccOut})
Acc0 = Acc1 = AccIn = AccOut = term()
List1 = [A]
List2 = [B]
A = B = term()
mapfoldr combines the operations of map/2 and foldr/3 into
one pass.
max(List) -> Max
Types:
List = [T, ...]
Max = T
T = term()
Returns the first element of List that compares greater than or equal to
all other elements of List.
member(Elem, List) -> boolean()
Types:
Elem = T
List = [T]
T = term()
Returns true if Elem matches some element of List,
otherwise false.
merge(ListOfLists) -> List1
Types:
ListOfLists = [List]
List = List1 = [T]
T = term()
Returns the sorted list formed by merging all the sub-lists of
ListOfLists. All sub-lists must be sorted prior to evaluating this
function. When two elements compare equal, the element from the sub-list with
the lowest position in ListOfLists is picked before the other
element.
merge(List1, List2) -> List3
Types:
List1 = [X]
List2 = [Y]
List3 = [(X | Y)]
X = Y = term()
Returns the sorted list formed by merging List1 and List2. Both
List1 and List2 must be sorted prior to evaluating this
function. When two elements compare equal, the element from List1 is
picked before the element from List2.
merge(Fun, List1, List2) -> List3
Types:
Fun = fun((A, B) -> boolean())
List1 = [A]
List2 = [B]
List3 = [(A | B)]
A = B = term()
Returns the sorted list formed by merging List1 and List2. Both
List1 and List2 must be sorted according to the ordering
function Fun prior to evaluating this function. Fun(A, B)
should return true if A compares less than or equal to B
in the ordering, false otherwise. When two elements compare equal, the
element from List1 is picked before the element from
List2.
merge3(List1, List2, List3) -> List4
Types:
List1 = [X]
List2 = [Y]
List3 = [Z]
List4 = [(X | Y | Z)]
X = Y = Z = term()
Returns the sorted list formed by merging List1, List2 and
List3. All of List1, List2 and List3 must be
sorted prior to evaluating this function. When two elements compare equal, the
element from List1, if there is such an element, is picked before the
other element, otherwise the element from List2 is picked before the
element from List3.
min(List) -> Min
Types:
List = [T, ...]
Min = T
T = term()
Returns the first element of List that compares less than or equal to all
other elements of List.
nth(N, List) -> Elem
Types:
N = integer() >= 1
Elem = T
T = term()
1..length(List)
List = [T, ...]
Returns the Nth element of List. For example:
> lists:nth(3, [a, b, c, d, e]). c
nthtail(N, List) -> Tail
Types:
N = integer() >= 0
Tail = [T]
T = term()
0..length(List)
List = [T, ...]
Returns the Nth tail of List, that is, the sublist of List
starting at N+1 and continuing up to the end of the list. For example:
> lists:nthtail(3, [a, b, c, d, e]). [d,e] > tl(tl(tl([a, b, c, d, e]))). [d,e] > lists:nthtail(0, [a, b, c, d, e]). [a,b,c,d,e] > lists:nthtail(5, [a, b, c, d, e]). []
partition(Pred, List) -> {Satisfying, NotSatisfying}
Types:
Pred = fun((Elem :: T) -> boolean())
List = Satisfying = NotSatisfying = [T]
T = term()
Partitions List into two lists, where the first list contains all
elements for which Pred(Elem) returns true, and the second list
contains all elements for which Pred(Elem) returns false.
Examples:
> lists:partition(fun(A) -> A rem 2 == 1 end, [1,2,3,4,5,6,7]). {[1,3,5,7],[2,4,6]} > lists:partition(fun(A) -> is_atom(A) end, [a,b,1,c,d,2,3,4,e]). {[a,b,c,d,e],[1,2,3,4]}See also splitwith/2 for a different way to partition a list.
prefix(List1, List2) -> boolean()
Types:
List1 = List2 = [T]
T = term()
Returns true if List1 is a prefix of List2, otherwise
false.
reverse(List1) -> List2
Types:
List1 = List2 = [T]
T = term()
Returns a list with the elements in List1 in reverse order.
reverse(List1, Tail) -> List2
Types:
List1 = [T]
Tail = term()
List2 = [T]
T = term()
Returns a list with the elements in List1 in reverse order, with the tail
Tail appended. For example:
> lists:reverse([1, 2, 3, 4], [a, b, c]). [4,3,2,1,a,b,c]
seq(From, To) -> Seq
seq(From, To, Incr) -> Seq
Types:
From = To = Incr = integer()
Seq = [integer()]
Returns a sequence of integers which starts with From and contains the
successive results of adding Incr to the previous element, until
To has been reached or passed (in the latter case, To is not an
element of the sequence). Incr defaults to 1.
Failure: If To<From-Incr and Incr is positive, or if
To>From-Incr and Incr is negative, or if Incr==0 and
From/=To.
The following equalities hold for all sequences:
length(lists:seq(From, To)) == To-From+1 length(lists:seq(From, To, Incr)) == (To-From+Incr) div IncrExamples:
> lists:seq(1, 10). [1,2,3,4,5,6,7,8,9,10] > lists:seq(1, 20, 3). [1,4,7,10,13,16,19] > lists:seq(1, 0, 1). [] > lists:seq(10, 6, 4). [] > lists:seq(1, 1, 0). [1]
sort(List1) -> List2
Types:
List1 = List2 = [T]
T = term()
Returns a list containing the sorted elements of List1.
sort(Fun, List1) -> List2
Types:
Fun = fun((A :: T, B :: T) -> boolean())
List1 = List2 = [T]
T = term()
Returns a list containing the sorted elements of List1, according to the
ordering function Fun. Fun(A, B) should return
true if A compares less than or equal to B in the
ordering, false otherwise.
split(N, List1) -> {List2, List3}
Types:
N = integer() >= 0
T = term()
0..length(List1)
List1 = List2 = List3 = [T]
Splits List1 into List2 and List3. List2 contains
the first N elements and List3 the rest of the elements (the
Nth tail).
splitwith(Pred, List) -> {List1, List2}
Types:
Pred = fun((T) -> boolean())
List = List1 = List2 = [T]
T = term()
Partitions List into two lists according to Pred.
splitwith/2 behaves as if it is defined as follows:
splitwith(Pred, List) -> {takewhile(Pred, List), dropwhile(Pred, List)}.Examples:
> lists:splitwith(fun(A) -> A rem 2 == 1 end, [1,2,3,4,5,6,7]). {[1],[2,3,4,5,6,7]} > lists:splitwith(fun(A) -> is_atom(A) end, [a,b,1,c,d,2,3,4,e]). {[a,b],[1,c,d,2,3,4,e]}See also partition/2 for a different way to partition a list.
sublist(List1, Len) -> List2
Types:
List1 = List2 = [T]
Len = integer() >= 0
T = term()
Returns the sub-list of List1 starting at position 1 and with (max)
Len elements. It is not an error for Len to exceed the length of
the list, in that case the whole list is returned.
sublist(List1, Start, Len) -> List2
Types:
List1 = List2 = [T]
Start = integer() >= 1
T = term()
1..(length(List1)+1)
Len = integer() >= 0
Returns the sub-list of List1 starting at Start and with (max)
Len elements. It is not an error for Start+Len to exceed the
length of the list.
> lists:sublist([1,2,3,4], 2, 2). [2,3] > lists:sublist([1,2,3,4], 2, 5). [2,3,4] > lists:sublist([1,2,3,4], 5, 2). []
subtract(List1, List2) -> List3
Types:
List1 = List2 = List3 = [T]
T = term()
Returns a new list List3 which is a copy of List1, subjected to
the following procedure: for each element in List2, its first
occurrence in List1 is deleted. For example:
> lists:subtract("123212", "212"). "312".lists:subtract(A, B) is equivalent to A -- B.
Warning:
The complexity of lists:subtract(A, B) is proportional to
length(A)*length(B), meaning that it will be very slow if both A
and B are long lists. (Using ordered lists and
ordsets:subtract/2 is a much better choice if both lists are long.)
suffix(List1, List2) -> boolean()
Types:
List1 = List2 = [T]
T = term()
Returns true if List1 is a suffix of List2, otherwise
false.
sum(List) -> number()
Types:
List = [number()]
Returns the sum of the elements in List.
takewhile(Pred, List1) -> List2
Types:
Pred = fun((Elem :: T) -> boolean())
List1 = List2 = [T]
T = term()
Takes elements Elem from List1 while Pred(Elem) returns
true, that is, the function returns the longest prefix of the list for
which all elements satisfy the predicate.
ukeymerge(N, TupleList1, TupleList2) -> TupleList3
Types:
N = integer() >= 1
TupleList2 = [T2]
TupleList3 = [(T1 | T2)]
T1 = T2 = Tuple
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = [T1]
Returns the sorted list formed by merging TupleList1 and
TupleList2. The merge is performed on the Nth element of each
tuple. Both TupleList1 and TupleList2 must be key-sorted without
duplicates prior to evaluating this function. When two tuples compare equal,
the tuple from TupleList1 is picked and the one from TupleList2
deleted.
ukeysort(N, TupleList1) -> TupleList2
Types:
N = integer() >= 1
Tuple = tuple()
1..tuple_size(Tuple)
TupleList1 = TupleList2 = [Tuple]
Returns a list containing the sorted elements of the list TupleList1
where all but the first tuple of the tuples comparing equal have been deleted.
Sorting is performed on the Nth element of the tuples.
umerge(ListOfLists) -> List1
Types:
ListOfLists = [List]
List = List1 = [T]
T = term()
Returns the sorted list formed by merging all the sub-lists of
ListOfLists. All sub-lists must be sorted and contain no duplicates
prior to evaluating this function. When two elements compare equal, the
element from the sub-list with the lowest position in ListOfLists is
picked and the other one deleted.
umerge(List1, List2) -> List3
Types:
List1 = [X]
List2 = [Y]
List3 = [(X | Y)]
X = Y = term()
Returns the sorted list formed by merging List1 and List2. Both
List1 and List2 must be sorted and contain no duplicates prior
to evaluating this function. When two elements compare equal, the element from
List1 is picked and the one from List2 deleted.
umerge(Fun, List1, List2) -> List3
Types:
Fun = fun((A, B) -> boolean())
List1 = [A]
List2 = [B]
List3 = [(A | B)]
A = B = term()
Returns the sorted list formed by merging List1 and List2. Both
List1 and List2 must be sorted according to the ordering
function Fun and contain no duplicates prior to evaluating this
function. Fun(A, B) should return true if A compares less
than or equal to B in the ordering, false otherwise. When two
elements compare equal, the element from List1 is picked and the one
from List2 deleted.
umerge3(List1, List2, List3) -> List4
Types:
List1 = [X]
List2 = [Y]
List3 = [Z]
List4 = [(X | Y | Z)]
X = Y = Z = term()
Returns the sorted list formed by merging List1, List2 and
List3. All of List1, List2 and List3 must be
sorted and contain no duplicates prior to evaluating this function. When two
elements compare equal, the element from List1 is picked if there is
such an element, otherwise the element from List2 is picked, and the
other one deleted.
unzip(List1) -> {List2, List3}
Types:
List1 = [{A, B}]
List2 = [A]
List3 = [B]
A = B = term()
"Unzips" a list of two-tuples into two lists, where the first list
contains the first element of each tuple, and the second list contains the
second element of each tuple.
unzip3(List1) -> {List2, List3, List4}
Types:
List1 = [{A, B, C}]
List2 = [A]
List3 = [B]
List4 = [C]
A = B = C = term()
"Unzips" a list of three-tuples into three lists, where the first list
contains the first element of each tuple, the second list contains the second
element of each tuple, and the third list contains the third element of each
tuple.
usort(List1) -> List2
Types:
List1 = List2 = [T]
T = term()
Returns a list containing the sorted elements of List1 where all but the
first element of the elements comparing equal have been deleted.
usort(Fun, List1) -> List2
Types:
Fun = fun((T, T) -> boolean())
List1 = List2 = [T]
T = term()
Returns a list which contains the sorted elements of List1 where all but
the first element of the elements comparing equal according to the ordering
function Fun have been deleted. Fun(A, B) should return
true if A compares less than or equal to B in the
ordering, false otherwise.
zip(List1, List2) -> List3
Types:
List1 = [A]
List2 = [B]
List3 = [{A, B}]
A = B = term()
"Zips" two lists of equal length into one list of two-tuples, where
the first element of each tuple is taken from the first list and the second
element is taken from corresponding element in the second list.
zip3(List1, List2, List3) -> List4
Types:
List1 = [A]
List2 = [B]
List3 = [C]
List4 = [{A, B, C}]
A = B = C = term()
"Zips" three lists of equal length into one list of three-tuples,
where the first element of each tuple is taken from the first list, the second
element is taken from corresponding element in the second list, and the third
element is taken from the corresponding element in the third list.
zipwith(Combine, List1, List2) -> List3
Types:
Combine = fun((X, Y) -> T)
List1 = [X]
List2 = [Y]
List3 = [T]
X = Y = T = term()
Combine the elements of two lists of equal length into one list. For each pair
X, Y of list elements from the two lists, the element in the result
list will be Combine(X, Y).
zipwith(fun(X, Y) -> {X,Y} end, List1, List2) is equivalent to
zip(List1, List2).
Example:
> lists:zipwith(fun(X, Y) -> X+Y end, [1,2,3], [4,5,6]). [5,7,9]
zipwith3(Combine, List1, List2, List3) -> List4
Types:
Combine = fun((X, Y, Z) -> T)
List1 = [X]
List2 = [Y]
List3 = [Z]
List4 = [T]
X = Y = Z = T = term()
Combine the elements of three lists of equal length into one list. For each
triple X, Y, Z of list elements from the three lists, the element in
the result list will be Combine(X, Y, Z).
zipwith3(fun(X, Y, Z) -> {X,Y,Z} end, List1, List2, List3) is
equivalent to zip3(List1, List2, List3).
Examples:
> lists:zipwith3(fun(X, Y, Z) -> X+Y+Z end, [1,2,3], [4,5,6], [7,8,9]). [12,15,18] > lists:zipwith3(fun(X, Y, Z) -> [X,Y,Z] end, [a,b,c], [x,y,z], [1,2,3]). [[a,x,1],[b,y,2],[c,z,3]]
stdlib 2.2 | Ericsson AB |