v/vlib/arrays/arrays.v

122 lines
2.2 KiB
V

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
// - shuffle - randomize array items order in place (allowing exit after n items)
// - merge - combine two sorted arrays and maintain sorted order
import rand
// min returns the minimum
[direct_array_access]
pub fn min<T>(a []T) T {
if a.len == 0 {
panic('.min called on an empty array')
}
mut val := a[0]
for i in 0 .. a.len {
if a[i] < val {
val = a[i]
}
}
return val
}
// max returns the maximum
[direct_array_access]
pub fn max<T>(a []T) T {
if a.len == 0 {
panic('.max called on an empty array')
}
mut val := a[0]
for i in 0 .. a.len {
if a[i] > val {
val = a[i]
}
}
return val
}
// idx_min returns the index of the first minimum
[direct_array_access]
pub fn idx_min<T>(a []T) int {
if a.len == 0 {
panic('.idxmin called on an empty array')
}
mut idx := 0
mut val := a[0]
for i in 0 .. a.len {
if a[i] < val {
val = a[i]
idx = i
}
}
return idx
}
// idx_max returns the index of the first maximum
[direct_array_access]
pub fn idx_max<T>(a []T) int {
if a.len == 0 {
panic('.idxmax called on an empty array')
}
mut idx := 0
mut val := a[0]
for i in 0 .. a.len {
if a[i] > val {
val = a[i]
idx = i
}
}
return idx
}
// shuffle randomizes the first n items of an array in place (all if n=0)
[direct_array_access]
pub fn shuffle<T>(mut a []T, n int) {
if n < 0 || n > a.len {
panic("shuffle's argument 'n' must be in range [0,a.len]")
}
cnt := if n == 0 { a.len - 1 } else { n }
for i in 0 .. cnt {
x := rand.int_in_range(i, a.len)
// swap
a_i := a[i]
a[i] = a[x]
a[x] = a_i
}
}
// merge two sorted arrays (ascending) and maintain sorted order
[direct_array_access]
pub fn merge<T>(a, 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
}