Pdtable

Pdtable is a Pandas.DataFrame(Python)-like class that is expanded from CSV::Table. It has some Pandas.DataFrame-like methods, for example read_csv. Pdtable infers each column's classes as a dtype. And you can specify them.

Installation

Add this line to your application's Gemfile:

gem 'pdtable'

And then execute:

$ bundle

Or install it yourself as:

$ gem install pdtable

Usage

Read CSV

You can read CSV with Pdtable::Table.new.

$ cat test/csv/default.csv
date,datetime,integer,float,string
2017/01/01,2017/01/01T00:00:00,1,1.1,string1
2017-01-02,2017-01-02 00:00:00,2,2.2,string2
20170103,,3,3.3,"string3"

> t = Pdtable::Table.new 'test/csv/default.csv'
 => #<Pdtable::Table mode:col_or_row row_count:4>

> puts t
date,datetime,integer,float,string
2017-01-01T00:00:00+00:00,2017-01-01T00:00:00+00:00,1,1.1,string1
2017-01-02T00:00:00+00:00,2017-01-02T00:00:00+00:00,2,2.2,string2
2017-01-03T00:00:00+00:00,,3,3.3,string3
 => nil

> t.to_a
 => [[:date, :datetime, :integer, :float, :string], [#<DateTime: 2017-01-01T00:00:00+00:00 ((2457755j,0s,0n),+0s,2299161j)>, #<DateTime: 2017-01-01T00:00:00+00:00 ((2457755j,0s,0n),+0s,2299161j)>, 1, 1.1, "string1"], [#<DateTime: 2017-01-02T00:00:00+00:00 ((2457756j,0s,0n),+0s,2299161j)>, #<DateTime: 2017-01-02T00:00:00+00:00 ((2457756j,0s,0n),+0s,2299161j)>, 2, 2.2, "string2"], [#<DateTime: 2017-01-03T00:00:00+00:00 ((2457757j,0s,0n),+0s,2299161j)>, nil, 3, 3.3, "string3"]]

dtype returns a hash contents column names and data classes.

> t.dtype
 => {:date=>DateTime, :datetime=>DateTime, :integer=>Integer, :float=>Float, :string=>String}

Options

> t = Pdtable::Table.new 'test/csv/default.csv', dtype: {date: Date, float: String}
 => #<Pdtable::Table mode:col_or_row row_count:4>

> t.to_a
 => [[:date, :datetime, :integer, :float, :string], [#<Date: 2017-01-01 ((2457755j,0s,0n),+0s,2299161j)>, #<DateTime: 2017-01-01T00:00:00+00:00 ((2457755j,0s,0n),+0s,2299161j)>, 1, "1.1", "string1"], [#<Date: 2017-01-02 ((2457756j,0s,0n),+0s,2299161j)>, #<DateTime: 2017-01-02T00:00:00+00:00 ((2457756j,0s,0n),+0s,2299161j)>, 2, "2.2", "string2"], [#<Date: 2017-01-03 ((2457757j,0s,0n),+0s,2299161j)>, nil, 3, "3.3", "string3"]]

> t = Pdtable::Table.new 'test/csv/default.csv', skiprows: 0
 => #<Pdtable::Table mode:col_or_row row_count:3>

> puts t
date,datetime,integer,float,string
2017-01-02T00:00:00+00:00,2017-01-02T00:00:00+00:00,2,2.2,string2
2017-01-03T00:00:00+00:00,,3,3.3,string3
 => nil

> t = Pdtable::Table.new 'test/csv/default.csv', skiprows: [1, 2]
 => #<Pdtable::Table mode:col_or_row row_count:2>

> puts t
date,datetime,integer,float,string
2017-01-01T00:00:00+00:00,2017-01-01T00:00:00+00:00,1,1.1,string1
 => nil

CSV::Table method

Of Course, you can use CSV::Table methods, and you can get CSV::Table instance with table.

> t[0]
 => #<CSV::Row date:#<DateTime: 2017-01-01T00:00:00+00:00 ((2457755j,0s,0n),+0s,2299161j)> datetime:#<DateTime: 2017-01-01T00:00:00+00:00 ((2457755j,0s,0n),+0s,2299161j)> integer:1 float:1.1 string:"string1">

> t.mode
 => :col_or_row

> t.headers
 => [:date, :datetime, :integer, :float, :string]

> t.table
 => #<CSV::Table mode:col_or_row row_count:4>

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake test to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/kohei-kimura/pdtable. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the Contributor Covenant code of conduct.

License

The gem is available as open source under the terms of the MIT License.

Code of Conduct

Everyone interacting in the Pdtable project’s codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.