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