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|
module arrays
// Common arrays functions:
// - min / max - return the value of the minumum / maximum
// - idx_min / idx_max - return the index of the first minumum / maximum
// - merge - combine two sorted arrays and maintain sorted order
// min returns the minimum
pub fn min<T>(a []T) T {
if a.len == 0 {
panic('.min called on an empty array')
}
mut val := a[0]
for e in a {
if e < val {
val = e
}
}
return val
}
// max returns the maximum
pub fn max<T>(a []T) T {
if a.len == 0 {
panic('.max called on an empty array')
}
mut val := a[0]
for e in a {
if e > val {
val = e
}
}
return val
}
// idx_min returns the index of the first minimum
pub fn idx_min<T>(a []T) int {
if a.len == 0 {
panic('.idx_min called on an empty array')
}
mut idx := 0
mut val := a[0]
for i, e in a {
if e < val {
val = e
idx = i
}
}
return idx
}
// idx_max returns the index of the first maximum
pub fn idx_max<T>(a []T) int {
if a.len == 0 {
panic('.idx_max called on an empty array')
}
mut idx := 0
mut val := a[0]
for i, e in a {
if e > val {
val = e
idx = i
}
}
return idx
}
// merge two sorted arrays (ascending) and maintain sorted order
[direct_array_access]
pub fn merge<T>(a []T, b []T) []T {
mut m := []T{len: a.len + b.len}
mut ia := 0
mut ib := 0
mut j := 0
// TODO efficient approach to merge_desc where: a[ia] >= b[ib]
for ia < a.len && ib < b.len {
if a[ia] <= b[ib] {
m[j] = a[ia]
ia++
} else {
m[j] = b[ib]
ib++
}
j++
}
// a leftovers
for ia < a.len {
m[j] = a[ia]
ia++
j++
}
// b leftovers
for ib < b.len {
m[j] = b[ib]
ib++
j++
}
return m
}
// group n arrays into a single array of arrays with n elements
pub fn group<T>(lists ...[]T) [][]T {
mut length := if lists.len > 0 { lists[0].len } else { 0 }
// calculate length of output by finding shortest input array
for ndx in 1 .. lists.len {
if lists[ndx].len < length {
length = lists[ndx].len
}
}
if length > 0 {
mut arr := [][]T{cap: length}
// append all combined arrays into the resultant array
for ndx in 0 .. length {
mut zipped := []T{cap: lists.len}
// combine each list item for the ndx position into one array
for list_ndx in 0 .. lists.len {
zipped << lists[list_ndx][ndx]
}
arr << zipped
}
return arr
}
return [][]T{}
}
|
