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std.range.Transversal/transversal - multiple declarations

Function transversal

Given a range of ranges, iterate transversally through the nth element of each of the enclosed ranges. This function is similar to unzip in other languages.

Transversal!(RangeOfRanges,opt) transversal(TransverseOptions opt = TransverseOptions.assumeJagged, RangeOfRanges) (
  RangeOfRanges rr,
  size_t n
);

Parameters

NameDescription
opt Controls the assumptions the function makes about the lengths of the ranges
rr An input range of random access ranges

Returns

At minimum, an input range. Range primitives such as bidirectionality and random access are given if the element type of rr provides them.

Example

import std.algorithm.comparison : equal;
int[][] x = new int[][2];
x[0] = [1, 2];
x[1] = [3, 4];
auto ror = transversal(x, 1);
assert(equal(ror, [ 2, 4 ]));

Example

The following code does a full unzip 

import std.algorithm.comparison : equal;
import std.algorithm.iteration : map;
int[][] y = [[1, 2, 3], [4, 5, 6]];
auto z = y.front.walkLength.iota.map!(i => transversal(y, i));
assert(equal!equal(z, [[1, 4], [2, 5], [3, 6]]));

Struct Transversal

Given a range of ranges, iterate transversally through the nth element of each of the enclosed ranges. This function is similar to unzip in other languages.

struct Transversal(Ror, TransverseOptions opt = TransverseOptions.assumeJagged) ;

Constructors

NameDescription
this (input, n) Construction from an input and an index.

Properties

NameTypeDescription
back[get, set] autoBidirectional primitives. They are offered if isBidirectionalRange!RangeOfRanges.
front[get, set] autoForward range primitives.
save[get] typeof(this)Forward range primitives.

Methods

NameDescription
moveAt (n) Random-access primitive. It is offered if isRandomAccessRange!RangeOfRanges && (opt == TransverseOptions.assumeNotJagged || opt == TransverseOptions.enforceNotJagged).
moveBack () Bidirectional primitives. They are offered if isBidirectionalRange!RangeOfRanges.
moveFront () Forward range primitives.
opIndex (n) Random-access primitive. It is offered if isRandomAccessRange!RangeOfRanges && (opt == TransverseOptions.assumeNotJagged || opt == TransverseOptions.enforceNotJagged).
opIndexAssign (val, n) Random-access primitive. It is offered if isRandomAccessRange!RangeOfRanges && (opt == TransverseOptions.assumeNotJagged || opt == TransverseOptions.enforceNotJagged).
opSlice (lower, upper) Slicing if offered if RangeOfRanges supports slicing and all the conditions for supporting indexing are met.
popBack () Bidirectional primitives. They are offered if isBidirectionalRange!RangeOfRanges.
popFront () Forward range primitives.

Parameters

NameDescription
opt Controls the assumptions the function makes about the lengths of the ranges
rr An input range of random access ranges

Returns

At minimum, an input range. Range primitives such as bidirectionality and random access are given if the element type of rr provides them.

Example

import std.algorithm.comparison : equal;
int[][] x = new int[][2];
x[0] = [1, 2];
x[1] = [3, 4];
auto ror = transversal(x, 1);
assert(equal(ror, [ 2, 4 ]));

Example

The following code does a full unzip 

import std.algorithm.comparison : equal;
import std.algorithm.iteration : map;
int[][] y = [[1, 2, 3], [4, 5, 6]];
auto z = y.front.walkLength.iota.map!(i => transversal(y, i));
assert(equal!equal(z, [[1, 4], [2, 5], [3, 6]]));

Authors

Andrei Alexandrescu, David Simcha, Jonathan M Davis, and Jack Stouffer. Credit for some of the ideas in building this module goes to Leonardo Maffi.

License

Boost License 1.0.