Class: SparkConnect::Column

Inherits:
Object
  • Object
show all
Defined in:
lib/spark_connect/column.rb

Overview

A column expression: a lazily-evaluated reference to a column or a computation over columns. Columns are immutable; operators and methods return new Columns.

A Column wraps a protobuf ‘Expression`. Build them with Functions.col, Functions.lit, by indexing a DataFrame (`df`), or by combining other columns with operators.

Examples:

F = SparkConnect::F
(F.col("age") + 1).alias("next_age")
F.col("name").like("a%") & (F.col("age") >= 18)

Constant Summary collapse

Proto = 
SparkConnect::Proto

Instance Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(expr) ⇒ Column

Returns a new instance of Column.

Parameters:



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# File 'lib/spark_connect/column.rb', line 26

def initialize(expr)
  @expr = expr
end

Instance Attribute Details

#expr ⇒ Spark::Connect::Expression (readonly)

Returns the wrapped protobuf expression.

Returns:



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# File 'lib/spark_connect/column.rb', line 23

def expr
  @expr
end

Class Method Details

.from_expr(expr) ⇒ Column

Wrap an existing protobuf expression.

Returns:



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# File 'lib/spark_connect/column.rb', line 38

def from_expr(expr)
  new(expr)
end

.from_name(name) ⇒ Column

An unresolved attribute reference by (possibly dotted) name. The special name ‘“*”` expands to all columns.

Parameters:

  • name (String)

Returns:



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# File 'lib/spark_connect/column.rb', line 47

def from_name(name)
  if name == "*"
    new(Proto::Expression.new(unresolved_star: Proto::Expression::UnresolvedStar.new))
  else
    new(Proto::Expression.new(
          unresolved_attribute: Proto::Expression::UnresolvedAttribute.new(unparsed_identifier: name.to_s)
        ))
  end
end

.infer_type(value) ⇒ Types::DataType

Infer the Spark Types::DataType for a Ruby value (used when building array/map literals). Mirrors PySpark’s literal type inference.

Parameters:

  • value (Object)

Returns:



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# File 'lib/spark_connect/column.rb', line 152

def infer_type(value)
  case value
  when nil then Types.null
  when true, false then Types.boolean
  when Integer
    value.between?(-2_147_483_648, 2_147_483_647) ? Types.integer : Types.long
  when Float, Rational then Types.double
  when BigDecimal then Types.decimal(38, 18)
  when String then value.encoding == Encoding::ASCII_8BIT ? Types.binary : Types.string
  when Symbol then Types.string
  when Time, DateTime then Types.timestamp
  when Date then Types.date
  when Array then Types.array(value.empty? ? Types.null : infer_type(value.find { |v| !v.nil? }))
  when Hash
    Types.map(value.empty? ? Types.string : infer_type(value.keys.first),
              value.empty? ? Types.string : infer_type(value.values.first))
  else
    raise IllegalArgumentError, "Cannot infer Spark type for #{value.class}"
  end
end

.invoke(name, *args, is_distinct: false) ⇒ Column

Build an ‘UnresolvedFunction` call column.

Parameters:

  • name (String) —

    the Spark function name.

  • args (Array<Column, Object>) —

    arguments (non-columns become literals).

  • is_distinct (Boolean) (defaults to: false)

Returns:



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# File 'lib/spark_connect/column.rb', line 74

def invoke(name, *args, is_distinct: false)
  new(Proto::Expression.new(
        unresolved_function: Proto::Expression::UnresolvedFunction.new(
          function_name: name.to_s,
          arguments: args.map { |a| to_col(a).to_expr },
          is_distinct: is_distinct
        )
      ))
end

.lit(value) ⇒ Column

Build a literal column from a Ruby value.

Parameters:

  • value (Object) —

    nil, Boolean, Integer, Float, String, Symbol, Time, Date, BigDecimal, Array, Hash, or an existing SparkConnect::Column.

Returns:



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# File 'lib/spark_connect/column.rb', line 62

def lit(value)
  return value if value.is_a?(Column)

  new(Proto::Expression.new(literal: to_literal(value)))
end

.to_col(value) ⇒ Column

Coerce a value into a SparkConnect::Column (literals are wrapped).

Returns:



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# File 'lib/spark_connect/column.rb', line 86

def to_col(value)
  value.is_a?(Column) ? value : lit(value)
end

.to_literal(value) ⇒ Spark::Connect::Expression::Literal

Encode a Ruby value as a protobuf ‘Expression.Literal`.

Parameters:

  • value (Object)

Returns:

  • (Spark::Connect::Expression::Literal) 


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# File 'lib/spark_connect/column.rb', line 94

def to_literal(value)
  l = Proto::Expression::Literal
  case value
  when nil
    l.new(null: Types.null.to_proto)
  when true, false
    l.new(boolean: value)
  when Integer
    if value.between?(-2_147_483_648, 2_147_483_647)
      l.new(integer: value)
    else
      l.new(long: value)
    end
  when Float
    l.new(double: value)
  when BigDecimal
    l.new(decimal: l::Decimal.new(value: value.to_s("F")))
  when Rational
    l.new(double: value.to_f)
  when String
    if value.encoding == Encoding::ASCII_8BIT
      l.new(binary: value)
    else
      l.new(string: value)
    end
  when Symbol
    l.new(string: value.to_s)
  when Time
    l.new(timestamp: (value.to_r * 1_000_000).to_i)
  when DateTime
    l.new(timestamp: (value.to_time.to_r * 1_000_000).to_i)
  when Date
    l.new(date: (value - Date.new(1970, 1, 1)).to_i)
  when Array
    elem_type = infer_array_element_type(value)
    l.new(array: l::Array.new(
      element_type: elem_type.to_proto,
      elements: value.map { |v| to_literal(v) }
    ))
  when Hash
    key_type = value.empty? ? Types.string : infer_type(value.keys.first)
    val_type = value.empty? ? Types.string : infer_type(value.values.first)
    l.new(map: l::Map.new(
      key_type: key_type.to_proto,
      value_type: val_type.to_proto,
      keys: value.keys.map { |k| to_literal(k) },
      values: value.values.map { |v| to_literal(v) }
    ))
  else
    raise IllegalArgumentError, "Unsupported literal value of type #{value.class}: #{value.inspect}"
  end
end

Instance Method Details

#! ⇒ Object Also known as: not 



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# File 'lib/spark_connect/column.rb', line 210

def !
  Column.invoke("not", self)
end

#!=(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 196

def !=(other) = bin_op("!=", other)

#%(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 186

def %(other) = bin_op("%", other)

#&(other) ⇒ Object

—- Boolean ———————————————————–



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# File 'lib/spark_connect/column.rb', line 207

def &(other) = bin_op("and", other)

#*(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 184

def *(other) = bin_op("*", other)

#**(other) ⇒ Column

Raise this column to the power of ‘other`.

Returns:



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# File 'lib/spark_connect/column.rb', line 192

def **(other) = bin_op("power", other)

#+(other) ⇒ Object

—- Arithmetic ——————————————————–



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# File 'lib/spark_connect/column.rb', line 182

def +(other) = bin_op("+", other)

#+@ ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 188

def +@ = self

#-(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 183

def -(other) = bin_op("-", other)

#-@ ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 187

def -@ = Column.invoke("negative", self)

#/(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 185

def /(other) = bin_op("/", other)

#<(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 197

def <(other) = bin_op("<", other)

#<=(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 198

def <=(other) = bin_op("<=", other)

#==(other) ⇒ Object

—- Comparison ——————————————————–



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# File 'lib/spark_connect/column.rb', line 195

def ==(other) = bin_op("==", other)

#>(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 199

def >(other) = bin_op(">", other)

#>=(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 200

def >=(other) = bin_op(">=", other)

#[](key) ⇒ Column

—- Complex-type access ———————————————- Extract an array element by index, a map value by key, or a struct field.

Returns:



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# File 'lib/spark_connect/column.rb', line 258

def [](key)
  get_item(key)
end

#alias(*names, metadata: nil) ⇒ Column Also known as: name, as

—- Aliasing / naming ————————————————- Assign one or more output names. With multiple names the expression must produce a struct/multiple columns (e.g. ‘inline`).

Parameters:

  • names (Array<String>)
  • metadata (Hash, nil) (defaults to: nil) —

    optional JSON metadata for a single alias.

Returns:



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# File 'lib/spark_connect/column.rb', line 283

def alias(*names, metadata: nil)
  a = Proto::Expression::Alias.new(expr: @expr, name: names.map(&:to_s))
  a.metadata = JSON.generate(metadata) if metadata
  Column.new(Proto::Expression.new(alias: a))
end

#asc ⇒ Object

—- Sort ordering —————————————————–



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# File 'lib/spark_connect/column.rb', line 310

def asc = sort_order(:SORT_DIRECTION_ASCENDING, :SORT_NULLS_FIRST)

#asc_nulls_first ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 312

def asc_nulls_first = sort_order(:SORT_DIRECTION_ASCENDING, :SORT_NULLS_FIRST)

#asc_nulls_last ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 313

def asc_nulls_last = sort_order(:SORT_DIRECTION_ASCENDING, :SORT_NULLS_LAST)

#between(lower, upper) ⇒ Column

True if ‘lower <= self <= upper`.

Returns:



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# File 'lib/spark_connect/column.rb', line 237

def between(lower, upper)
  (self >= lower) & (self <= upper)
end

#bitwise_and(other) ⇒ Object

—- Bitwise ———————————————————–



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# File 'lib/spark_connect/column.rb', line 216

def bitwise_and(other) = bin_op("&", other)

#bitwise_or(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 217

def bitwise_or(other) = bin_op("|", other)

#bitwise_xor(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 218

def bitwise_xor(other) = bin_op("^", other)

#cast(data_type) ⇒ Column Also known as: as_type, astype

—- Casting ———————————————————– Cast to another type, given either a Types::DataType or a DDL type string (e.g. ‘“int”`, `“decimal(10,2)”`).

Parameters:

Returns:



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# File 'lib/spark_connect/column.rb', line 297

def cast(data_type)
  c = Proto::Expression::Cast.new(expr: @expr)
  if data_type.is_a?(String)
    c.type_str = data_type
  else
    c.type = data_type.to_proto
  end
  Column.new(Proto::Expression.new(cast: c))
end

#contains(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 245

def contains(other) = bin_op("contains", other)

#desc ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 311

def desc = sort_order(:SORT_DIRECTION_DESCENDING, :SORT_NULLS_LAST)

#desc_nulls_first ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 314

def desc_nulls_first = sort_order(:SORT_DIRECTION_DESCENDING, :SORT_NULLS_FIRST)

#desc_nulls_last ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 315

def desc_nulls_last = sort_order(:SORT_DIRECTION_DESCENDING, :SORT_NULLS_LAST)

#endswith(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 247

def endswith(other) = bin_op("endswith", other)

#eq_null_safe(other) ⇒ Column

Null-safe equality (‘<=>` in Spark SQL): `null <=> null` is true.

Returns:



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# File 'lib/spark_connect/column.rb', line 204

def eq_null_safe(other) = bin_op("<=>", other)

#get_field(name) ⇒ Column

Extract a struct field by name.

Returns:



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# File 'lib/spark_connect/column.rb', line 272

def get_field(name)
  get_item(name.to_s)
end

#get_item(key) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 262

def get_item(key)
  Column.new(Proto::Expression.new(
               unresolved_extract_value: Proto::Expression::UnresolvedExtractValue.new(
                 child: @expr, extraction: Column.lit(key).to_expr
               )
             ))
end

#ilike(pattern) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 244

def ilike(pattern) = bin_op("ilike", pattern)

#is_nan ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 223

def is_nan = Column.invoke("isNaN", self)

#is_not_null ⇒ Object Also known as: isNotNull 



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# File 'lib/spark_connect/column.rb', line 222

def is_not_null = Column.invoke("isNotNull", self)

#is_null ⇒ Object Also known as: isNull

—- Null / membership predicates ————————————-



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# File 'lib/spark_connect/column.rb', line 221

def is_null = Column.invoke("isNull", self)

#isin(*values) ⇒ Column Also known as: in_list

True if the column’s value is in ‘values`.

Returns:



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# File 'lib/spark_connect/column.rb', line 229

def isin(*values)
  values = values.first if values.size == 1 && values.first.is_a?(Array)
  Column.invoke("in", self, *Array(values))
end

#like(pattern) ⇒ Object

—- String predicates ————————————————-



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# File 'lib/spark_connect/column.rb', line 242

def like(pattern) = bin_op("like", pattern)

#otherwise(value) ⇒ Column

Provide the default (ELSE) value for a CASE expression.

Returns:



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# File 'lib/spark_connect/column.rb', line 334

def otherwise(value)
  unless @expr.expr_type == :unresolved_function && @expr.unresolved_function.function_name == "when"
    raise IllegalArgumentError, "otherwise() can only be applied on a Column previously generated by when()"
  end

  args = @expr.unresolved_function.arguments.to_a + [Column.to_col(value).to_expr]
  Column.new(Proto::Expression.new(
               unresolved_function: Proto::Expression::UnresolvedFunction.new(function_name: "when", arguments: args)
             ))
end

#over(window) ⇒ Column

—- Windowing ——————————————————— Define a windowed aggregation / analytic computation over this column.

Parameters:

Returns:



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# File 'lib/spark_connect/column.rb', line 350

def over(window)
  w = Proto::Expression::Window.new(
    window_function: @expr,
    partition_spec: window.partition_spec,
    order_spec: window.order_spec
  )
  w.frame_spec = window.frame_spec if window.frame_spec
  Column.new(Proto::Expression.new(window: w))
end

#rlike(pattern) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 243

def rlike(pattern) = bin_op("rlike", pattern)

#startswith(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 246

def startswith(other) = bin_op("startswith", other)

#substr(start, len) ⇒ Column

Substring of length ‘len` starting at 1-based position `start`.

Returns:



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# File 'lib/spark_connect/column.rb', line 251

def substr(start, len)
  Column.invoke("substr", self, start, len)
end

#to_expr ⇒ Spark::Connect::Expression

Returns:



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# File 'lib/spark_connect/column.rb', line 31

def to_expr
  @expr
end

#to_s ⇒ Object Also known as: inspect 



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# File 'lib/spark_connect/column.rb', line 360

def to_s
  "Column<#{@expr.expr_type}>"
end

#when(condition, value) ⇒ Column

—- CASE WHEN ——————————————————— Add a branch to a CASE expression started by Functions#when.

Returns:



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# File 'lib/spark_connect/column.rb', line 321

def when(condition, value)
  unless @expr.expr_type == :unresolved_function && @expr.unresolved_function.function_name == "when"
    raise IllegalArgumentError, "when() can only be applied on a Column previously generated by when()"
  end

  args = @expr.unresolved_function.arguments.to_a + [Column.to_col(condition).to_expr, Column.to_col(value).to_expr]
  Column.new(Proto::Expression.new(
               unresolved_function: Proto::Expression::UnresolvedFunction.new(function_name: "when", arguments: args)
             ))
end

#|(other) ⇒ Object 



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# File 'lib/spark_connect/column.rb', line 208

def |(other) = bin_op("or", other)