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Add new prefixes, add some more interface functions

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Thomas Roehl
2022-03-17 14:18:07 +01:00
parent 8c6fa4c4bc
commit a6e40789e4
5 changed files with 200 additions and 43 deletions
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31
README.md
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@@ -5,8 +5,10 @@ When working with metrics, the problem comes up that they may use different unit
In order to enable unit comparison and conversion, the ccUnits package provides some helpers:
There are basically two important functions:
```go
NewUnit(unit string) Unit
GetUnitPrefixFactor(in Unit, out Unit) (func(value float64) float64, error) // Get conversion function for the value
NewUnit(unit string) Unit // create a new unit from some string like 'GHz', 'Mbyte' or 'kevents/s'
func GetUnitUnitFactor(in Unit, out Unit) (func(value float64) float64, error) // Get conversion function between two units
func GetPrefixFactor(in Prefix, out Prefix) func(value float64) float64 // Get conversion function between two prefixes
func GetUnitPrefixFactor(in Unit, out Prefix) (func(value float64) float64, Unit) // Get conversion function for prefix changes and the new unit for further use
type Unit interface {
Valid() bool
@@ -26,14 +28,35 @@ v := NewUnit("foo")
fmt.Println(v.Valid()) // false
```
If you have two units and need the conversion function:
If you have two units or other components and need the conversion function:
```go
// Get conversion functions for 'kB' to 'MBytes'
u1 := NewUnit("kB")
u2 := NewUnit("MBytes")
convFunc, err := GetUnitPrefixFactor(u1, u2) // Returns an error if the units have different measures
convFunc, err := GetUnitUnitFactor(u1, u2) // Returns an error if the units have different measures
if err == nil {
v2 := convFunc(v1)
fmt.Printf("%f %s\n", v2, u2.Short())
}
// Get conversion function for 'kB' -> 'G' prefix.
// Returns the function and the new unit 'GBytes'
p1 := NewPrefix("G")
convFunc, u_p1 := GetUnitPrefixFactor(u1, p1)
// or
// convFunc, u_p1 := GetUnitPrefixStringFactor(u1, "G")
if convFunc != nil {
v2 := convFunc(v1)
fmt.Printf("%f %s\n", v2, u_p1.Short())
}
// Get conversion function for two prefixes: 'G' -> 'T'
p2 := NewPrefix("T")
convFunc = GetPrefixPrefixFactor(p1, p2)
if convFunc != nil {
v2 := convFunc(v1)
fmt.Printf("%f %s -> %f %s\n", v1, p1.Prefix(), v2, p2.Prefix())
}
```
(In the ClusterCockpit ecosystem the separation between values and units if useful since they are commonly not stored as a single entity but the value is a field in the CCMetric while unit is a tag or a meta information).