Documentation
¶
Overview ¶
Package funcs provides functionality to apply mathematical functions to DataFrames.
Index ¶
Constants ¶
This section is empty.
Variables ¶
var ErrUndefined = errors.New("undefined")
ErrUndefined indicates that the PiecewiseFuncDefn's domain is not defined for a given row.
Functions ¶
func Evaluate ¶
func Evaluate(ctx context.Context, df *dataframe.DataFrame, fn PiecewiseFuncDefn, col interface{}, opts ...EvaluateOptions) error
Evaluate applies a PiecewiseFuncDefn to a particular Series in a DataFrame.
Example:
fn := funcs.RegFunc("sin((2*𝜋*x)/24)")
funcs.Evaluate(ctx, df, fn, 1)
Types ¶
type EvaluateOptions ¶
type EvaluateOptions struct {
// CustomFns adds custom functions to be used within fn.
//
// Example:
//
// CustomFns: map[string]func(args ...float64) float64{
// // Add sinc function: https://en.wikipedia.org/wiki/Sinc_function
// "sinc": func(args ...float64) float64 {
// if args[0] == 0 {
// return 1
// }
// return math.Sin(args[0]) / args[0]
// }
// }
//
CustomFns map[string]func(args ...float64) float64
// CustomConstants adds custom constants to be used within fn.
// NOTE: π, 𝜋, pi, Φ, phi, e, E are already provided unless over-ridden here.
//
// Example:
//
// CustomConstants: map[string]float64{"ħ": 6.62607015E-34/(2*math.Pi)}
CustomConstants map[string]float64
// DontLock can be set to true if the DataFrame should not be locked.
DontLock bool
// Range is used to limit which rows the PiecewiseFuncDefn gets applied to.
Range *dataframe.Range
// NoConcurrency is not yet implemented.
NoConcurrency bool
}
EvaluateOptions modifies the behavior of the Evaluate function.
type PiecewiseFuncDefn ¶
type PiecewiseFuncDefn []SubFuncDefn
PiecewiseFuncDefn represents a piecewise function. A piecewise function is a function that is defined on a sequence of intervals.
See: https://mathworld.wolfram.com/PiecewiseFunction.html
Example:
fn := []funcs.SubFunc{
{
Fn: "sin(x)+2*y",
Domain: &[]dataframe.Range{dataframe.RangeFinite(0, 2)}[0],
},
{
Fn: "0",
Domain: nil,
},
}
type SubFuncDefn ¶
type SubFuncDefn struct {
// Fn is a string representing the function. Most functions from the math package that return a single float64 are supported.
// The equivalent function name is all lower-cased. Therefore RoundToEven becomes roundtoeven. See https://golang.org/pkg/math/.
// The variables used in Fn must correspond to the Series' names in the DataFrame. Custom functions and constants can be defined
// and added using the options.
//
// Example: "sin(x)+2*y"
//
Fn string
// Domain of Fn based on DataFrame's rows.
Domain *dataframe.Range
}
SubFuncDefn represents a subset of the piecewise function. PiecewiseFuncDefn consists of potentially numerous SubFuncDefn's over its relevant domain. The domain is defined based on the DataFrame's rows.
func RegFunc ¶
func RegFunc(fn string) []SubFuncDefn
RegFunc represents a regular function not split into different domain segments.
Source Files