memory

package
v0.0.8 Latest Latest
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 Go to latest Published: May 24, 2026 License: MIT Imports: 16 Imported by: 0

Documentation

Overview

Package memory provides a lightweight Go-slice-backed compute engine for the dataset package. It implements dataset.ColumnFactory, dataset.BuilderFactory, dataset.Aggregator, and dataset.Caster.

Usage: 

eng := memory.NewEngine(context.Background())
f := eng.(dataset.ColumnFactory)
ds, _ := f.FromColumns(
    dataset.NewSchema(dataset.FloatCol("x"), dataset.StringCol("label")),
    f.NewFloat64Column("x", []float64{1, 2, 3}),
    f.NewStringColumn("label", []string{"a", "b", "c"}),
)

Index

Constants

This section is empty.

Variables

View Source 
var (
	// ErrUnsupportedType is returned for unsupported column types.
	ErrUnsupportedType = errors.New("memory: unsupported column type")

	// ErrLengthMismatch is returned when column lengths don't match.
	ErrLengthMismatch = errors.New("memory: column length mismatch")

	// ErrEmptyColumn is returned when an operation requires non-empty data.
	ErrEmptyColumn = errors.New("memory: empty column")

	// ErrRequiresFloat64 is returned when a float64 column is required.
	ErrRequiresFloat64 = errors.New("memory: operation requires float64 column")

	// ErrRequiresInt64 is returned when an int64 column is required.
	ErrRequiresInt64 = errors.New("memory: operation requires int64 column")

	// ErrRequiresNumeric is returned when a numeric column is required.
	ErrRequiresNumeric = errors.New("memory: operation requires numeric column")

	// ErrJoinKeyMismatch is returned when join key types don't match.
	ErrJoinKeyMismatch = errors.New("memory: join key type mismatch")

	// ErrTakeTypeMismatch is returned when a Take/Select result has unexpected type.
	ErrTakeTypeMismatch = errors.New("memory: unexpected result type from Take/Select")

	// ErrOutOfRange is returned when a parameter value is out of the expected range.
	ErrOutOfRange = errors.New("memory: value out of range")
)

Sentinel errors for the memory engine package.

Functions

This section is empty.

Types

type Engine 

type Engine struct {
	// contains filtered or unexported fields
}

Engine is the Go-slice compute backend.

func NewEngine 

func NewEngine(ctx context.Context) *Engine

NewEngine creates a memory engine with the given lifecycle context.

func (*Engine) Abs 

func (e *Engine) Abs(col dataset.AnyColumn) (dataset.AnyColumn, error)

Abs returns the absolute value of each element.

func (*Engine) Acos 

func (e *Engine) Acos(col dataset.AnyColumn) (dataset.AnyColumn, error)

Acos returns the arccosine of each element.

func (*Engine) AddCols 

func (e *Engine) AddCols(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

AddCols returns element-wise addition of two float64 columns.

func (*Engine) AddScalar 

func (e *Engine) AddScalar(col dataset.AnyColumn, val float64) (dataset.AnyColumn, error)

AddScalar adds a scalar value to each element of a float64 column.

func (*Engine) Asin 

func (e *Engine) Asin(col dataset.AnyColumn) (dataset.AnyColumn, error)

Asin returns the arcsine of each element.

func (*Engine) Atan 

func (e *Engine) Atan(col dataset.AnyColumn) (dataset.AnyColumn, error)

Atan returns the arctangent of each element.

func (*Engine) Atan2 

func (e *Engine) Atan2(y, x dataset.AnyColumn) (dataset.AnyColumn, error)

Atan2 returns the two-argument arctangent of (y, x).

func (*Engine) BitAnd 

func (e *Engine) BitAnd(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

BitAnd returns element-wise bitwise AND of two int64 columns.

func (*Engine) BitNot 

func (e *Engine) BitNot(col dataset.AnyColumn) (dataset.AnyColumn, error)

BitNot returns the bitwise complement of each int64 element.

func (*Engine) BitOr 

func (e *Engine) BitOr(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

BitOr returns element-wise bitwise OR of two int64 columns.

func (*Engine) BitShiftLeft 

func (e *Engine) BitShiftLeft(col dataset.AnyColumn, n int) (dataset.AnyColumn, error)

BitShiftLeft shifts each int64 element left by n bits.

func (*Engine) BitShiftRight 

func (e *Engine) BitShiftRight(col dataset.AnyColumn, n int) (dataset.AnyColumn, error)

BitShiftRight shifts each int64 element right by n bits.

func (*Engine) BitXor 

func (e *Engine) BitXor(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

BitXor returns element-wise bitwise XOR of two int64 columns.

func (*Engine) Boxplot added in v0.0.5 

func (e *Engine) Boxplot(yCol, groupCol dataset.AnyColumn, whisker string, notch bool) (dataset.Table, error)

Boxplot computes the five-number summary for a numeric column.

func (*Engine) Cast 

func (e *Engine) Cast(col dataset.AnyColumn, target dataset.DType) (dataset.AnyColumn, error)

Cast converts a column to the specified dtype.

func (*Engine) Ceil 

func (e *Engine) Ceil(col dataset.AnyColumn) (dataset.AnyColumn, error)

Ceil returns the smallest integer ≥ each element.

func (*Engine) Combine 

func (e *Engine) Combine(datasets ...dataset.Table) (dataset.Table, error)

Combine horizontally concatenates datasets with equal row counts.

func (*Engine) Complete 

func (e *Engine) Complete(ds dataset.Table, cols ...string) (dataset.Table, error)

Complete generates all combinations of the specified columns' unique values, filling missing rows with null values.

func (*Engine) Concatenate 

func (e *Engine) Concatenate(ds dataset.Table, col string, from []string, sep string) (dataset.Table, error)

Concatenate joins multiple string columns into one with a separator.

func (*Engine) Context 

func (e *Engine) Context() context.Context

Context returns the engine's lifecycle context.

func (*Engine) Cos 

func (e *Engine) Cos(col dataset.AnyColumn) (dataset.AnyColumn, error)

Cos returns the cosine of each element (radians).

func (*Engine) Count 

func (e *Engine) Count(col dataset.AnyColumn) (dataset.AnyColumn, error)

Count returns the row count of a column as a single-row int64 column.

func (*Engine) CumMax 

func (e *Engine) CumMax(col dataset.AnyColumn) (dataset.AnyColumn, error)

CumMax returns the cumulative maximum of a numeric column.

func (*Engine) CumMin 

func (e *Engine) CumMin(col dataset.AnyColumn) (dataset.AnyColumn, error)

CumMin returns the cumulative minimum of a numeric column.

func (*Engine) CumSum 

func (e *Engine) CumSum(col dataset.AnyColumn) (dataset.AnyColumn, error)

CumSum returns the cumulative sum of a float64 column.

func (*Engine) DenseRank 

func (e *Engine) DenseRank(col dataset.AnyColumn) (dataset.AnyColumn, error)

DenseRank returns dense rank (no gaps). E.g. [10,20,20,30] → [1,2,2,3].

func (*Engine) DivCols 

func (e *Engine) DivCols(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

DivCols returns element-wise division of two float64 columns.

func (*Engine) DropNA 

func (e *Engine) DropNA(ds dataset.Table, cols ...string) (dataset.Table, error)

DropNA removes rows containing null values in the specified columns.

func (*Engine) Erf 

func (e *Engine) Erf(col dataset.AnyColumn) (dataset.AnyColumn, error)

Erf returns the Gauss error function of each element.

func (*Engine) Exp 

func (e *Engine) Exp(col dataset.AnyColumn) (dataset.AnyColumn, error)

Exp returns e raised to the power of each element.

func (*Engine) Fill 

func (e *Engine) Fill(col dataset.AnyColumn, dir dataset.FillDirection) (dataset.AnyColumn, error)

Fill forward- or backward-fills null values in a column.

func (*Engine) Filter 

func (e *Engine) Filter(ds dataset.Table, mask dataset.Masker) (dataset.Table, error)

Filter returns a new Table containing only rows where mask evaluates true.

func (*Engine) FilterIndices 

func (e *Engine) FilterIndices(mask []bool) []int

FilterIndices returns the indices where mask is true.

func (*Engine) First added in v0.0.5 

func (e *Engine) First(col dataset.AnyColumn) (dataset.AnyColumn, error)

First returns the first element of a column as a single-row column.

func (*Engine) Floor 

func (e *Engine) Floor(col dataset.AnyColumn) (dataset.AnyColumn, error)

Floor returns the greatest integer ≤ each element.

func (*Engine) FromColumns 

func (e *Engine) FromColumns(schema *dataset.Schema, cols ...dataset.AnyColumn) (dataset.Table, error)

FromColumns constructs a Table from a schema and pre-built columns.

func (*Engine) Histogram added in v0.0.5 

func (e *Engine) Histogram(col dataset.AnyColumn, nBins int) (dataset.Table, error)

Histogram bins a numeric column into equal-width bins.

func (*Engine) Join 

func (e *Engine) Join(left, right dataset.Table, spec dataset.JoinSpec) (dataset.Table, error)

Join implements the Joiner interface with a hash-join algorithm. It supports Inner, Left, Right, Full, Semi, and Anti joins.

func (*Engine) KDE added in v0.0.5 

func (e *Engine) KDE(ctx context.Context, col dataset.AnyColumn, bandwidth float64, points int) (dataset.Table, error)

KDE computes kernel density estimation over a numeric column.

func (*Engine) Lag 

func (e *Engine) Lag(col dataset.AnyColumn, n int) (dataset.AnyColumn, error)

Lag shifts a column's values down by n positions, filling with NaN/zero.

func (*Engine) Last added in v0.0.5 

func (e *Engine) Last(col dataset.AnyColumn) (dataset.AnyColumn, error)

Last returns the last element of a column as a single-row column.

func (*Engine) Lead 

func (e *Engine) Lead(col dataset.AnyColumn, n int) (dataset.AnyColumn, error)

Lead shifts a column's values up by n positions, filling with NaN/zero.

func (*Engine) LinearFit added in v0.0.5 

func (e *Engine) LinearFit(xCol, yCol dataset.AnyColumn, nOut int) (dataset.Table, error)

LinearFit computes OLS linear regression y = a + b*x.

func (*Engine) LinearFitSE added in v0.0.5 

func (e *Engine) LinearFitSE(xCol, yCol dataset.AnyColumn, nOut int) (dataset.Table, error)

LinearFitSE computes OLS regression with 95% confidence bands.

func (*Engine) Ln 

func (e *Engine) Ln(col dataset.AnyColumn) (dataset.AnyColumn, error)

Ln returns the natural logarithm of each element.

func (*Engine) LoessFit added in v0.0.5 

func (e *Engine) LoessFit(ctx context.Context, xCol, yCol dataset.AnyColumn, nOut int) (dataset.Table, error)

LoessFit computes locally weighted regression (LOESS).

func (*Engine) LoessFitSE added in v0.0.5 

func (e *Engine) LoessFitSE(ctx context.Context, xCol, yCol dataset.AnyColumn, nOut int) (dataset.Table, error)

LoessFitSE computes LOESS with approximate 95% confidence bands. Uses local residual variance to estimate SE at each grid point.

func (*Engine) Log2 

func (e *Engine) Log2(col dataset.AnyColumn) (dataset.AnyColumn, error)

Log2 returns the base-2 logarithm of each element.

func (*Engine) Log10 

func (e *Engine) Log10(col dataset.AnyColumn) (dataset.AnyColumn, error)

Log10 returns the base-10 logarithm of each element.

func (*Engine) Mean 

func (e *Engine) Mean(col dataset.AnyColumn) (dataset.AnyColumn, error)

Mean returns the arithmetic mean of a float64 column as a single-row column.

func (*Engine) Median 

func (e *Engine) Median(col dataset.AnyColumn) (dataset.AnyColumn, error)

Median returns the median of a float64 column as a single-row column.

func (*Engine) MinMax 

func (e *Engine) MinMax(col dataset.AnyColumn) (dataset.AnyColumn, dataset.AnyColumn, error)

MinMax returns two single-row columns containing the min and max values.

func (*Engine) Mode added in v0.0.5 

func (e *Engine) Mode(col dataset.AnyColumn) (dataset.AnyColumn, error)

Mode returns the most frequent value as a single-row column. For ties, the first value encountered wins.

func (*Engine) MulCols 

func (e *Engine) MulCols(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

MulCols returns element-wise multiplication of two float64 columns.

func (*Engine) MulScalar 

func (e *Engine) MulScalar(col dataset.AnyColumn, val float64) (dataset.AnyColumn, error)

MulScalar multiplies each element of a float64 column by a scalar value.

func (*Engine) Name 

func (e *Engine) Name() string

Name returns "memory".

func (*Engine) Neg 

func (e *Engine) Neg(col dataset.AnyColumn) (dataset.AnyColumn, error)

Neg returns the negation of each element.

func (*Engine) NewBoolColumn 

func (e *Engine) NewBoolColumn(name string, data []bool) dataset.AnyColumn

NewBoolColumn creates a bool column from the given slice.

func (*Engine) NewBuilder 

func (e *Engine) NewBuilder(schema *dataset.Schema) dataset.Builder

NewBuilder creates a typed row-appender for the given schema.

func (*Engine) NewDateColumn added in v0.0.6 

func (e *Engine) NewDateColumn(name string, days []int64) dataset.AnyColumn

NewDateColumn creates a date-only column from int64 days since the Unix epoch (1970-01-01). Compatible with Arrow DATE32.

func (*Engine) NewDateFromString added in v0.0.6 

func (e *Engine) NewDateFromString(name string, values []string) (dataset.AnyColumn, error)

NewDateFromString creates a date column by parsing date strings using rickb777/date. Supports ISO 8601 ("2006-01-02", "20060102"). Returns an error if any value fails to parse.

func (*Engine) NewDateFromTime added in v0.0.6 

func (e *Engine) NewDateFromTime(name string, times []time.Time) dataset.AnyColumn

NewDateFromTime creates a date column from Go time.Time values. Each value is truncated to midnight UTC and stored as days since epoch.

func (*Engine) NewFloat64Column 

func (e *Engine) NewFloat64Column(name string, data []float64) dataset.AnyColumn

NewFloat64Column creates a float64 column from the given slice.

func (*Engine) NewInt64Column 

func (e *Engine) NewInt64Column(name string, data []int64) dataset.AnyColumn

NewInt64Column creates an int64 column from the given slice.

func (*Engine) NewStringColumn 

func (e *Engine) NewStringColumn(name string, data []string) dataset.AnyColumn

NewStringColumn creates a string column from the given slice.

func (*Engine) NewTimeColumn added in v0.0.6 

func (e *Engine) NewTimeColumn(name string, nanos []int64) dataset.AnyColumn

NewTimeColumn creates a time-of-day column from int64 nanoseconds since midnight (00:00:00.000000000). Compatible with Arrow TIME64(ns).

func (*Engine) NewTimestampColumn 

func (e *Engine) NewTimestampColumn(name string, data []int64) dataset.AnyColumn

NewTimestampColumn creates a timestamp column (int64-backed) from the given slice.

func (*Engine) NewTimestampFromString added in v0.0.6 

func (e *Engine) NewTimestampFromString(name string, values []string) (dataset.AnyColumn, error)

NewTimestampFromString creates a timestamp column by parsing date/time strings. Tries RFC3339 first, then ISO 8601 date (via rickb777/date), then common layouts. Returns an error if any value fails to parse.

func (*Engine) NewTimestampFromTime added in v0.0.6 

func (e *Engine) NewTimestampFromTime(name string, times []time.Time) dataset.AnyColumn

NewTimestampFromTime creates a timestamp column from Go time.Time values. Each value is converted to UnixNano (int64 nanoseconds since epoch).

func (*Engine) PercentRank 

func (e *Engine) PercentRank(col dataset.AnyColumn) (dataset.AnyColumn, error)

PercentRank returns (rank - 1) / (n - 1) as float64. Returns 0 for single element.

func (*Engine) Percentile added in v0.0.5 

func (e *Engine) Percentile(col dataset.AnyColumn, p float64) (dataset.AnyColumn, error)

Percentile returns the p-th quantile as a single-row float64 column. p ∈ [0,1]. Uses sort-based linear interpolation (R-7 method).

func (*Engine) PivotLonger 

func (e *Engine) PivotLonger(ds dataset.Table, spec dataset.PivotLongerSpec) (dataset.Table, error)

PivotLonger reshapes a wide dataset to long format. Columns listed in spec.Cols are "gathered" into two new columns: spec.NamesTo (holds original column names) and spec.ValuesTo (holds values). All other columns are repeated for each gathered column.

func (*Engine) PivotWider 

func (e *Engine) PivotWider(ds dataset.Table, spec dataset.PivotWiderSpec) (dataset.Table, error)

PivotWider reshapes a long dataset to wide format. spec.NamesFrom identifies the column whose unique values become new column names. spec.ValuesFrom identifies the column whose values fill the new columns. All other columns are the "id" columns that define unique rows.

func (*Engine) Pow 

func (e *Engine) Pow(col dataset.AnyColumn, exp float64) (dataset.AnyColumn, error)

Pow raises each element to the given exponent.

func (*Engine) Rank 

func (e *Engine) Rank(col dataset.AnyColumn) (dataset.AnyColumn, error)

Rank returns competition rank (1-indexed). Ties get the same rank, next rank skips. E.g. [10,20,20,30] → [1,2,2,4].

func (*Engine) ReplaceNA 

func (e *Engine) ReplaceNA(col dataset.AnyColumn, defaultVal float64) (dataset.AnyColumn, error)

ReplaceNA replaces null (NaN) values in a float64 column with defaultVal.

func (*Engine) Round 

func (e *Engine) Round(col dataset.AnyColumn) (dataset.AnyColumn, error)

Round rounds each element to the nearest integer.

func (*Engine) RowNumber 

func (e *Engine) RowNumber(n int) (dataset.AnyColumn, error)

RowNumber returns a 1-indexed sequential column of length n.

func (*Engine) Select 

func (e *Engine) Select(col dataset.AnyColumn, indices []int) (dataset.AnyColumn, error)

Select returns a new column containing only the rows at the given indices.

func (*Engine) Separate 

func (e *Engine) Separate(ds dataset.Table, col string, into []string, sep string) (dataset.Table, error)

Separate splits a string column by a delimiter into multiple columns.

func (*Engine) Sigmoid 

func (e *Engine) Sigmoid(col dataset.AnyColumn) (dataset.AnyColumn, error)

Sigmoid returns the logistic sigmoid of each element.

func (*Engine) Sign 

func (e *Engine) Sign(col dataset.AnyColumn) (dataset.AnyColumn, error)

Sign returns the sign of each element (-1, 0, or 1).

func (*Engine) Sin 

func (e *Engine) Sin(col dataset.AnyColumn) (dataset.AnyColumn, error)

Sin returns the sine of each element (radians).

func (*Engine) Slice 

func (e *Engine) Slice(col dataset.AnyColumn, start, end int) (dataset.AnyColumn, error)

Slice returns a sub-column from start (inclusive) to end (exclusive).

func (*Engine) SortIndices 

func (e *Engine) SortIndices(col dataset.AnyColumn) ([]int, error)

SortIndices returns the permutation that sorts the column ascending.

func (*Engine) Sqrt 

func (e *Engine) Sqrt(col dataset.AnyColumn) (dataset.AnyColumn, error)

Sqrt returns the square root of each element.

func (*Engine) Stack 

func (e *Engine) Stack(datasets ...dataset.Table) (dataset.Table, error)

Stack vertically concatenates datasets with compatible schemas.

func (*Engine) StdDev added in v0.0.5 

func (e *Engine) StdDev(col dataset.AnyColumn) (dataset.AnyColumn, error)

StdDev returns the sample standard deviation as a single-row float64 column.

func (*Engine) SubCols 

func (e *Engine) SubCols(a, b dataset.AnyColumn) (dataset.AnyColumn, error)

SubCols returns element-wise subtraction of two float64 columns.

func (*Engine) Sum 

func (e *Engine) Sum(col dataset.AnyColumn) (dataset.AnyColumn, error)

Sum returns the sum of a numeric column as a single-row column.

func (*Engine) Tan 

func (e *Engine) Tan(col dataset.AnyColumn) (dataset.AnyColumn, error)

Tan returns the tangent of each element (radians).

func (*Engine) Tanh 

func (e *Engine) Tanh(col dataset.AnyColumn) (dataset.AnyColumn, error)

Tanh returns the hyperbolic tangent of each element.

func (*Engine) Variance 

func (e *Engine) Variance(col dataset.AnyColumn) (dataset.AnyColumn, error)

Variance returns the sample variance of a float64 column as a single-row column.

Source Files

View all Source files

Directories

Path Synopsis
Package csv provides the Memory CSV engine driver.
 Package csv provides the Memory CSV engine driver.
Package parquet provides the Memory Parquet engine driver.
 Package parquet provides the Memory Parquet engine driver.

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