19 KiB
module arrays
Contents
- append
- binary_search
- carray_to_varray
- chunk
- chunk_while
- concat
- copy
- distinct
- each
- each_indexed
- filter_indexed
- find_first
- find_last
- flat_map
- flat_map_indexed
- flatten
- fold
- fold_indexed
- group
- group_by
- idx_max
- idx_min
- index_of_first
- index_of_last
- join_to_string
- lower_bound
- map_indexed
- map_of_counts
- map_of_indexes
- max
- merge
- min
- partition
- reduce
- reduce_indexed
- reverse_iterator
- rotate_left
- rotate_right
- sum
- uniq
- uniq_all_repeated
- uniq_only
- uniq_only_repeated
- upper_bound
- window
- ReverseIterator[T]
- ReverseIterator
- WindowAttribute
append
fn append[T](a []T, b []T) []T
append the second array b to the first array a, and return the result. Note, that unlike arrays.concat, arrays.append is less flexible, but more efficient, since it does not require you to use ...a for the second parameter.
Example
arrays.append([1, 3, 5, 7], [2, 4, 6, 8]) // => [1, 3, 5, 7, 2, 4, 6, 8]
binary_search
fn binary_search[T](array []T, target T) !int
binary_search, requires array to be sorted, returns index of found item or error. Binary searches on sorted lists can be faster than other array searches because at maximum the algorithm only has to traverse log N elements
Example
arrays.binary_search([1, 2, 3, 4], 4)! // => 3
carray_to_varray
fn carray_to_varray[T](c_array_data voidptr, items int) []T
carray_to_varray copies a C byte array into a V array of type T. See also: cstring_to_vstring
chunk
fn chunk[T](array []T, size int) [][]T
chunk array into a single array of arrays where each element is the next size elements of the original.
Example
arrays.chunk([1, 2, 3, 4, 5, 6, 7, 8, 9], 2) // => [[1, 2], [3, 4], [5, 6], [7, 8], [9]]
chunk_while
fn chunk_while[T](a []T, predicate fn (before T, after T) bool) [][]T
chunk_while splits the input array a into chunks of varying length, using the predicate, passing to it pairs of adjacent elements before and after. Each chunk, will contain all ajdacent elements, for which the predicate returned true. The chunks are split between the before and after elements, for which the predicate returned false.
Examples
assert arrays.chunk_while([0,9,2,2,3,2,7,5,9,5],fn(x int,y int)bool{return x<=y})==[[0,9],[2,2,3],[2,7],[5,9],[5]]
assert arrays.chunk_while('aaaabbbcca'.runes(),fn(x rune,y rune)bool{return x==y})==[[`a`,`a`,`a`,`a`],[`b`,`b`,`b`],[`c`,`c`],[`a`]]
assert arrays.chunk_while('aaaabbbcca'.runes(),fn(x rune,y rune)bool{return x==y}).map({it[0]:it.len})==[{`a`:4},{`b`:3},{`c`:2},{`a`:1}]
concat
fn concat[T](a []T, b ...T) []T
concatenate an array with an arbitrary number of additional values.
Note: if you have two arrays, you should simply use the << operator directly.
Examples
assert arrays.concat([1, 2, 3], 4, 5, 6) == [1, 2, 3, 4, 5, 6]
assert arrays.concat([1, 2, 3], ...[4, 5, 6]) == [1, 2, 3, 4, 5, 6]
mut arr := arrays.concat([1, 2, 3], 4); arr << [10,20]; assert arr == [1,2,3,4,10,20] // note: arr is mutable
copy
fn copy[T](mut dst []T, src []T) int
copy copies the src array elements to the dst array. The number of the elements copied is the minimum of the length of both arrays. Returns the number of elements copied.
distinct
fn distinct[T](a []T) []T
distinct returns all distinct elements from the given array a. The results are guaranteed to be unique, i.e. not have duplicates. See also arrays.uniq, which can be used to achieve the same goal, but needs you to first sort the array.
Example
assert arrays.distinct( [5, 5, 1, 5, 2, 1, 1, 9] ) == [1, 2, 5, 9]
each
fn each[T](a []T, cb fn (elem T))
each calls the callback fn cb, for each element of the given array a.
each_indexed
fn each_indexed[T](a []T, cb fn (i int, e T))
each_indexed calls the callback fn cb, for each element of the given array a. It passes the callback both the index of the current element, and the element itself.
filter_indexed
fn filter_indexed[T](array []T, predicate fn (idx int, elem T) bool) []T
filter_indexed filters elements based on predicate function being invoked on each element with its index in the original array.
find_first
fn find_first[T](array []T, predicate fn (elem T) bool) ?T
find_first returns the first element that matches the given predicate. Returns none if no match is found.
Example
arrays.find_first([1, 2, 3, 4, 5], fn (i int) bool { return i == 3 })? // => 3
find_last
fn find_last[T](array []T, predicate fn (elem T) bool) ?T
find_last returns the last element that matches the given predicate. Returns none if no match is found.
Example
arrays.find_last([1, 2, 3, 4, 5], fn (i int) bool { return i == 3})? // => 3
flat_map
fn flat_map[T, R](array []T, transform fn (elem T) []R) []R
flat_map creates a new array populated with the flattened result of calling transform function being invoked on each element of list.
flat_map_indexed
fn flat_map_indexed[T, R](array []T, transform fn (idx int, elem T) []R) []R
flat_map_indexed creates a new array with the flattened result of calling the transform fn, invoked on each idx,elem pair from the original.
flatten
fn flatten[T](array [][]T) []T
flatten flattens n + 1 dimensional array into n dimensional array.
Example
arrays.flatten[int]([[1, 2, 3], [4, 5]]) // => [1, 2, 3, 4, 5]
fold
fn fold[T, R](array []T, init R, fold_op fn (acc R, elem T) R) R
fold sets acc = init, then successively calls acc = fold_op(acc, elem) for each element in array. returns acc.
Example
// Sum the length of each string in an array
a := ['Hi', 'all']
r := arrays.fold[string, int](a, 0,
fn (r int, t string) int { return r + t.len })
assert r == 5
fold_indexed
fn fold_indexed[T, R](array []T, init R, fold_op fn (idx int, acc R, elem T) R) R
fold_indexed sets acc = init, then successively calls acc = fold_op(idx, acc, elem) for each element in array. returns acc.
group
fn group[T](arrs ...[]T) [][]T
group n arrays into a single array of arrays with n elements. This function is analogous to the "zip" function of other languages. To fully interleave two arrays, follow this function with a call to flatten.
Note: An error will be generated if the type annotation is omitted.
Example
arrays.group[int]([1, 2, 3], [4, 5, 6]) // => [[1, 4], [2, 5], [3, 6]]
group_by
fn group_by[K, V](array []V, grouping_op fn (val V) K) map[K][]V
group_by groups together elements, for which the grouping_op callback produced the same result.
Example
arrays.group_by[int, string](['H', 'el', 'lo'], fn (v string) int { return v.len }) // => {1: ['H'], 2: ['el', 'lo']}
idx_max
fn idx_max[T](array []T) !int
idx_max returns the index of the maximum value in the array.
Example
arrays.idx_max([1, 2, 3, 0, 9])! // => 4
idx_min
fn idx_min[T](array []T) !int
idx_min returns the index of the minimum value in the array.
Example
arrays.idx_min([1, 2, 3, 0, 9])! // => 3
index_of_first
fn index_of_first[T](array []T, predicate fn (idx int, elem T) bool) int
index_of_first returns the index of the first element of array, for which the predicate fn returns true. If predicate does not return true for any of the elements, then index_of_first will return -1.
Example
assert arrays.index_of_first([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 2
index_of_last
fn index_of_last[T](array []T, predicate fn (idx int, elem T) bool) int
index_of_last returns the index of the last element of array, for which the predicate fn returns true. If predicate does not return true for any of the elements, then index_of_last will return -1.
Example
assert arrays.index_of_last([4,5,0,7,0,9], fn(idx int, x int) bool { return x == 0 }) == 4
join_to_string
fn join_to_string[T](array []T, separator string, transform fn (elem T) string) string
join_to_string takes in a custom transform function and joins all elements into a string with the specified separator
lower_bound
fn lower_bound[T](array []T, val T) !T
returns the smallest element >= val, requires array to be sorted.
Example
arrays.lower_bound([2, 4, 6, 8], 3)! // => 4
map_indexed
fn map_indexed[T, R](array []T, transform fn (idx int, elem T) R) []R
map_indexed creates a new array with the result of calling the transform fn, invoked on each idx,elem pair from the original.
map_of_counts
fn map_of_counts[T](array []T) map[T]int
map_of_counts returns a map, where each key is an unique value in array. Each value in that map for that key, is how many times that value occurs in array. It can be useful for building histograms of discrete measurements.
Example
assert arrays.map_of_counts([1,2,3,4,4,2,1,4,4]) == {1: 2, 2: 2, 3: 1, 4: 4}
map_of_indexes
fn map_of_indexes[T](array []T) map[T][]int
map_of_indexes returns a map, where each key is an unique value in array. Each value in that map for that key, is an array, containing the indexes in array, where that value has been found.
Example
assert arrays.map_of_indexes([1,2,3,4,4,2,1,4,4,999]) == {1: [0, 6], 2: [1, 5], 3: [2], 4: [3, 4, 7, 8], 999: [9]}
max
fn max[T](array []T) !T
max returns the maximum value in the array.
Example
arrays.max([1, 2, 3, 0, 9])! // => 9
merge
fn merge[T](a []T, b []T) []T
merge two sorted arrays (ascending) and maintain sorted order.
Example
arrays.merge([1, 3, 5, 7], [2, 4, 6, 8]) // => [1, 2, 3, 4, 5, 6, 7, 8]
min
fn min[T](array []T) !T
min returns the minimum value in the array.
Example
arrays.min([1, 2, 3, 0, 9])! // => 0
partition
fn partition[T](array []T, predicate fn (elem T) bool) ([]T, []T)
partition splits the original array into pair of lists. The first list contains elements for which the predicate fn returned true, while the second list contains elements for which the predicate fn returned false.
reduce
fn reduce[T](array []T, reduce_op fn (acc T, elem T) T) !T
reduce sets acc = array[0], then successively calls acc = reduce_op(acc, elem) for each remaining element in array. returns the accumulated value in acc. returns an error if the array is empty. See also: fold.
Example
arrays.reduce([1, 2, 3, 4, 5], fn (t1 int, t2 int) int { return t1 * t2 })! // => 120
reduce_indexed
fn reduce_indexed[T](array []T, reduce_op fn (idx int, acc T, elem T) T) !T
reduce_indexed sets acc = array[0], then successively calls acc = reduce_op(idx, acc, elem) for each remaining element in array. returns the accumulated value in acc. returns an error if the array is empty. See also: fold_indexed.
reverse_iterator
fn reverse_iterator[T](a []T) ReverseIterator[T]
reverse_iterator can be used to iterate over the elements in an array. i.e. you can use this syntax: for elem in arrays.reverse_iterator(a) { .
rotate_left
fn rotate_left[T](mut array []T, mid int)
rotate_left rotates the array in-place. It does it in such a way, that the first mid elements of the array, move to the end, while the last array.len - mid elements move to the front. After calling rotate_left, the element previously at index mid will become the first element in the array.
Example
mut x := [1,2,3,4,5,6]
arrays.rotate_left(mut x, 2)
println(x) // [3, 4, 5, 6, 1, 2]
rotate_right
fn rotate_right[T](mut array []T, k int)
rotate_right rotates the array in-place. It does it in such a way, that the first array.len - k elements of the array, move to the end, while the last k elements move to the front. After calling rotate_right, the element previously at index array.len - k will become the first element in the array.
Example
mut x := [1,2,3,4,5,6]
arrays.rotate_right(mut x, 2)
println(x) // [5, 6, 1, 2, 3, 4]
sum
fn sum[T](array []T) !T
sum up array, return an error, when the array has no elements.
Example
arrays.sum([1, 2, 3, 4, 5])! // => 15
uniq
fn uniq[T](a []T) []T
uniq filters the adjacent matching elements from the given array. All adjacent matching elements, are merged to their first occurrence, so the output will have no repeating elements.
Note: uniq does not detect repeats, unless they are adjacent. You may want to call a.sorted() on your array, before passing the result to arrays.uniq(). See also arrays.distinct, which is essentially arrays.uniq(a.sorted()) .
Examples
assert arrays.uniq( []int{} ) == []
assert arrays.uniq( [1, 1] ) == [1]
assert arrays.uniq( [2, 1] ) == [2, 1]
assert arrays.uniq( [5, 5, 1, 5, 2, 1, 1, 9] ) == [5, 1, 5, 2, 1, 9]
uniq_all_repeated
fn uniq_all_repeated[T](a []T) []T
uniq_all_repeated produces all adjacent matching elements from the given array. Unique elements, with no duplicates are removed. The output will contain all the duplicated elements, repeated just like they were in the original.
Note: uniq_all_repeated does not detect repeats, unless they are adjacent. You may want to call a.sorted() on your array, before passing the result to arrays.uniq_all_repeated().
Examples
assert arrays.uniq_all_repeated( []int{} ) == []
assert arrays.uniq_all_repeated( [1, 5] ) == []
assert arrays.uniq_all_repeated( [5, 5] ) == [5,5]
assert arrays.uniq_all_repeated( [5, 5, 1, 5, 2, 1, 1, 9] ) == [5, 5, 1, 1]
uniq_only
fn uniq_only[T](a []T) []T
uniq_only filters the adjacent matching elements from the given array. All adjacent matching elements, are removed. The output will contain only the elements that did not have any adjacent matches.
Note: uniq_only does not detect repeats, unless they are adjacent. You may want to call a.sorted() on your array, before passing the result to arrays.uniq_only().
Examples
assert arrays.uniq_only( []int{} ) == []
assert arrays.uniq_only( [1, 1] ) == []
assert arrays.uniq_only( [2, 1] ) == [2, 1]
assert arrays.uniq_only( [1, 5, 5, 1, 5, 2, 1, 1, 9] ) == [1, 1, 5, 2, 9]
uniq_only_repeated
fn uniq_only_repeated[T](a []T) []T
uniq_only_repeated produces the adjacent matching elements from the given array. Unique elements, with no duplicates are removed. Adjacent matching elements, are reduced to just 1 element per repeat group.
Note: uniq_only_repeated does not detect repeats, unless they are adjacent. You may want to call a.sorted() on your array, before passing the result to arrays.uniq_only_repeated().
Examples
assert arrays.uniq_only_repeated( []int{} ) == []
assert arrays.uniq_only_repeated( [1, 5] ) == []
assert arrays.uniq_only_repeated( [5, 5] ) == [5]
assert arrays.uniq_only_repeated( [5, 5, 1, 5, 2, 1, 1, 9] ) == [5, 1]
upper_bound
fn upper_bound[T](array []T, val T) !T
returns the largest element <= val, requires array to be sorted.
Example
arrays.upper_bound([2, 4, 6, 8], 3)! // => 2
window
fn window[T](array []T, attr WindowAttribute) [][]T
get snapshots of the window of the given size sliding along array with the given step, where each snapshot is an array.- size - snapshot size
step- gap size between each snapshot, default is 1.
Examples
arrays.window([1, 2, 3, 4], size: 2) // => [[1, 2], [2, 3], [3, 4]]
arrays.window([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], size: 3, step: 2) // => [[1, 2, 3], [3, 4, 5], [5, 6, 7], [7, 8, 9]]
ReverseIterator[T]
next
fn (mut iter ReverseIterator[T]) next() ?&T
next is the required method, to implement an iterator in V. It returns none when the iteration should stop. Otherwise it returns the current element of the array.
free
fn (iter &ReverseIterator[T]) free()
free frees the iterator resources.
ReverseIterator
struct ReverseIterator[T] {
mut:
a []T
i int
}
ReverseIterator provides a convenient way to iterate in reverse over all elements of an array without allocations. I.e. it allows you to use this syntax: for elem in arrays.reverse_iterator(a) { .
WindowAttribute
struct WindowAttribute {
pub:
size int
step int = 1
}