README.md in cevennes-0.13.0 vs README.md in cevennes-1.0.0
- old
+ new
@@ -4,19 +4,56 @@
[](http://travis-ci.org/jmettraux/cevennes)
[](http://badge.fury.io/rb/cevennes)
Diffs CSVs by lines, focusing on a single ID
+
## usage
-TODO
+Given two CSV strings and an identifier name, cevennes may compute a diff:
+```ruby
+require 'cevennes'
+
+cvs0 = %{
+ id,name,age
+ 0,John,33
+ 1,Jean-Baptiste,43
+ 3,Luke,21
+}.strip + "\n"
+cvs1 = %{
+ id,name,age
+ 0,John,33
+ 1,Jean-Baptiste,44
+ 4,Matthew,20
+}.strip + "\n"
+
+d = Cevennes.diff('id', cvs0, cvs1)
```
-csv0 = %{
- }
-csv1 = %{
- }
-pp Cevennes.diff('ISIN', csv0, csv1)
+
+`d` will yield:
+```ruby
+[
+ [ 'keys', 1, [ 'id', 'name', 'age' ],
+ 1, [ 'id', 'name', 'age' ] ],
+ [ 'stats',
+ { '=' => 1, '!' => 1, '-' => 1, '+' => 1,
+ 'l0' => 3, 'l1' => 3 } ],
+ [ '=', 2, [ '0', 'John', '33'],
+ 2, nil ],
+ [ '!', 3, [ '1', 'Jean-Baptiste', '43' ],
+ 3, [ '1', 'Jean-Baptiste', '44' ] ],
+ [ '-', 4, [ '3', 'Luke', '21'],
+ -1, nil ],
+ [ '+', -1, nil,
+ 4, [ '4', 'Matthew', '20' ] ]
+]
```
+It's a list where the first entry is a recap of the keys used in the old and the new CSV strings (the integer is the line number (starting at 1) where the keys where found.
+
+The second entry is a summary of the changes, altered `!` line count, removed `-` line count, added `+` line count, old length `l0`, new length `l1`, and unchanged `=` line count.
+
+The remaining entries are the (non-)changes themselves, from line 1 to the end.
+
## LICENSE
MIT, see [LICENSE.txt](LICENSE.txt)