ruby/red-arrow/README.md

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# Red Arrow - Apache Arrow Ruby

Red Arrow is the Ruby bindings of Apache Arrow. Red Arrow is based on GObject Introspection.

[Apache Arrow](https://arrow.apache.org/) is an in-memory columnar data store. It's used by many products for data analytics.

[GObject Introspection](https://wiki.gnome.org/action/show/Projects/GObjectIntrospection) is a middleware for language bindings of C library. GObject Introspection can generate language bindings automatically at runtime.

Red Arrow uses [Apache Arrow GLib](https://github.com/apache/arrow/tree/main/c_glib) and [gobject-introspection gem](https://rubygems.org/gems/gobject-introspection) to generate Ruby bindings of Apache Arrow.

Apache Arrow GLib is a C wrapper for [Apache Arrow C++](https://github.com/apache/arrow/tree/main/cpp). GObject Introspection can't use Apache Arrow C++ directly. Apache Arrow GLib is a bridge between Apache Arrow C++ and GObject Introspection.

gobject-introspection gem is a Ruby bindings of GObject Introspection. Red Arrow uses GObject Introspection via gobject-introspection gem.

## Install

You need to install Apache Arrow GLib to install Red Arrow. You can automate it by enabling [rubygems-requirements-system](https://github.com/ruby-gnome/rubygems-requirements-system/). If you want to install Apache Arrow GLib manually, see [Apache Arrow install document](https://arrow.apache.org/install/) for details.

If you want to install Red Arrow by Bundler, you can add the followings to your `Gemfile`:

```ruby
plugin "rubygems-requirements-system"

gem "red-arrow"
```

If you want to install Red Arrow by RubyGems, you can use the following command line:

```console
$ gem install rubygems-requirements-system red-arrow
```

## Usage

```ruby
require "arrow"

table = Arrow::Table.load("/dev/shm/data.arrow")
# Process data in table
table.save("/dev/shm/data-processed.arrow")
```

## Development

Note that you need to install Apache Arrow C++/GLib at master before preparing Red Arrow. See also:

  * For Apache Arrow C++: https://arrow.apache.org/docs/developers/cpp/building.html
  * For Apache Arrow GLib: https://github.com/apache/arrow/blob/main/c_glib/README.md

```console
$ cd ruby/red-arrow
$ bundle install
$ bundle exec rake test
```

### For macOS with Homebrew

```console
$ cd ruby/red-arrow
$ bundle install
$ brew install apache-arrow --head
$ brew install apache-arrow-glib --head
$ bundle exec rake test
```