Ruby red-arrow

A library for serializting/deserializing and interacting with various columnar data formats (ex. parquet).

Documentation

api docs	https://www.rubydoc.info/gems/red-arrow/11.0.0
github	https://github.com/apache/arrow/tree/main/ruby/red-arrow

Usage

# instantiation
table = Arrow::Table.new(
  "name" => ["luke", "leia", "anakin"],
  "age" => [5, 5, 25]
)
table = Arrow::load("foo.parquet", format: :parquet)

# serialize
buf = Arrow::ResizableBuffer.new(1024)
table.save(buf, format: :parquet)
buf.data.to_s  # << serialized table

# deserialize
buf = Arrow::Buffer.new("..serialized-parquet..")
table = Arrow::Table.load(buf, format: :parquet)

table.n_rows                   # number of rows
table.column_names             # names of columns

table.slice(1, 4)              # new table w/ rows between 1-4
table.group("name")            # group by a value
table.slice(1, 1).raw_records  # json-esque data

table.select_columns("name", "age")  # only return these columns
table
  .select_columns(..)
  .each_column { |col|.each_with_index { |row| puts row } }  # each row value for selected column

sub-tables are defined as structs

datatype = Arrow::StructDataType.new(
  year: { type: :int32 }, 
  month: { type: :int32 }, 
  day: { type: :inte32 },
)
values = Arrow::StructArray.new(datatype, [[2020, 2021], [6, 7], [21, 25])
table = Arrow::Table.new(date: values)