README.md in fast_excel-0.1.7 vs README.md in fast_excel-0.2.0

@@ -20,24 +20,72 @@
 
 worksheet.write_row(0, ["message", "price", "date"], bold)
 
 for i in 1..1000
   worksheet.write_row(i, ["Hello", (rand * 10_000_000).round(2), Time.now])
-
-  # Or manually
-  # worksheet.write_string(i, 0, "Hello", nil)
-  # worksheet.write_number(i, 1, (rand * 10_000_000).round(2), nil)
-  # date = Libxlsxwriter::Datetime.new
-  # date[:year] = 2017
-  # date[:month] = 2
-  # date[:day] = 24
-  # date[:hour] = i % 24
-  # date[:min] = i % 60
-  # date[:sec] = i % 60
-  # worksheet.write_datetime(i, 2, date, nil)
 end
 
 workbook.close
 ```
 
 This repositiry and gem contain sources of [libxlsxwriter](https://github.com/jmcnamara/libxlsxwriter)
 
+## Benchmarks
+
+1000 rows:
+```
+Comparison:
+           FastExcel:       31.7 i/s
+               Axslx:        8.0 i/s - 3.98x  slower
+          write_xlsx:        6.9 i/s - 4.62x  slower
+```
+
+20000 rows:
+```
+Comparison:
+           FastExcel:        1.4 i/s
+               Axslx:        0.4 i/s - 3.46x  slower
+          write_xlsx:        0.1 i/s - 17.04x  slower
+```
+
+Max memory usage, generating 100k rows:
+```
+FastExcel   - 20 MB
+Axslx       - 60 MB
+write_axslx - 100 MB
+```
+
+## Install
+
+```ruby
+# Gemfile
+gem 'fast_excel'
+```
+Or
+```
+gem install fast_excel
+```
+
+## API
+
+This gem is FFI binding for libxlsxwriter C library with some syntax sugar. All original functions is avaliable, for example:
+
+```ruby
+Libxlsxwriter.worksheet_activate(worksheet) # => will call void worksheet_activate(lxw_worksheet *worksheet)
+# or shorter:
+worksheet.activate
+```
+
+Full libxlsxwriter documentation: [http://libxlsxwriter.github.io/](http://libxlsxwriter.github.io/)
+
+Helper Methods:
+
+* `FastExcel.open(filename = nil, constant_memory: false, default_format: {})` - open new workbook, if `filename` is nil - it will craete tmp file, `default_format` will be called with `workbook.default_format.set(...)`
+* `FastExcel.date_num(time, offset = nil)` - generate Excel's internal date value, number of days since 1900-Jan-01, works faster then creating `Libxlsxwriter::Datetime` struct. `offset` argument is number hours from UTC, e.g. `3.5`
+* `FastExcel.print_ffi_obj(object)` - print FFI object fields, just for debugging
+* `workbook.bold_cell_format` - shortcut for creating bold format
+* `workbook.number_format(num_format)` - create number or date format, for money usually: `"#,##0.00"`, for date: `"[$-409]m/d/yy h:mm AM/PM;@"`
+* `workbook.read_string` - close workbook, read file to string, delete file (only if tmp file)
+* `workbook.remove_tmp_file` - delete tmp file (only if tmp file)
+* `worksheet.write_row(row_num, array_of_mixed_value, formats = nil)` - write values one by one, detecting type automatically. `formats` can be array, or Format object or nil
+* `format.font_family` - alias for `format.font_name`
+* `workbook.default_format.font_size` - set it to 0 if you want to use default font size (that what user set in Excel settings)