README.md in matplotlib-0.1.0.alpha.20170419a vs README.md in matplotlib-0.1.0.alpha.20170426

@@ -1,11 +1,10 @@
 # Matplotlib
 
-Welcome to your new gem! In this directory, you'll find the files you need to be able to package up your Ruby library into a gem. Put your Ruby code in the file `lib/matplotlib`. To experiment with that code, run `bin/console` for an interactive prompt.
+This library enables to directly call [matplotlib](https://matplotlib.org/) from Ruby language.
+This is built on top of [pycall](https://github.com/mrkn/pycall).
 
-TODO: Delete this and the text above, and describe your gem
-
 ## Installation
 
 Add this line to your application's Gemfile:
 
 ```ruby
@@ -16,14 +15,38 @@
 
     $ bundle
 
 Or install it yourself as:
 
-    $ gem install matplotlib
+    $ gem install --pre matplotlib
 
 ## Usage
 
-TODO: Write usage instructions here
+### Using pyplot in irb console or standalone scripts
+
+Example usage:
+
+    require 'matplotlib/pyplot'
+    plt = Matplotlib::Pyplot
+
+    xs = [*1..100].map {|x| (x - 50) * Math::PI / 100.0 }
+    ys = xs.map {|x| Math.sin(x) }
+
+    plt.plot(xs, ys)
+    plt.show()
+
+### IRuby integration
+
+`matplotlib/iruby` provides integration between IRuby notebook and matplotlib.
+This functionality can be enabled by calling `Matplotlib::IRuby.activate`.
+
+    require 'matplotlib/iruby'
+    Matplotlib::IRuby.activate
+
+`matplotlib/iruby` also loads `matplotlib/pyplot`, so you can use `Matplotlib::Pyplot` module without explicitly requireing `matplotlib/pyplot`.
+And this introduces a post execution hook which put figures that are created in a cell just below the execution result of the cell.
+
+See ipynb files in [examples](examples) to see example usages.
 
 ## Development
 
 After checking out the repo, run `bin/setup` to install dependencies. Then, run `rake spec` to run the tests. You can also run `bin/console` for an interactive prompt that will allow you to experiment.