In computing, a bitmap is a mapping from some domain (for example, a range of integers) to bits, that is, values which are zero or one. It is also called a bit array or bitmap index.
This is an Elixir implementation of a bit array. Two implementations are provided as part of the library, Binary and Integer. Integers are the default due to clear performance superiority based on benchmarks provided below.
It is a fast space efficient data structure for lookups.
Note: Index is zero based in the implementation
iex> bitmap = Bitmap.new(5)
<<0::size(5)>> # 00000
iex> Bitmap.set(bitmap, 2)
<<4::size(5)>> # 00100
iex> bitmap |> Bitmap.set(2) |> Bitmap.set(3)
<<6::size(5)>> # 00110
iex> bitmap |> Bitmap.set(2) |> Bitmap.set(3) |> Bitmap.unset(2)
<<2::size(5)>> # 00010Read the latest documentation here for elaborate description and more examples on how to use the library.
Results are based on sources present inside the bench/ directory.
Bitmaps of size 1,000,000 are used to get benchmark on performance of the two implementations provided in the library - Binary and Integer.
Benchmark Bitmap.Integer.at 100000000 0.05 µs/op
Benchmark Bitmap.Integer.unset_all 100000000 0.06 µs/op
Benchmark Bitmap.Integer.set? 100000000 0.07 µs/op
Benchmark Bitmap.Integer.new 10000000 0.11 µs/op
Benchmark Bitmap.Integer.set 500000 7.50 µs/op
Benchmark Bitmap.Integer.toggle 500000 7.52 µs/op
Benchmark Bitmap.Integer.toggle_all 100000 21.33 µs/op
Benchmark Bitmap.Integer.unset 100000 22.83 µs/op
Benchmark Bitmap.Binary.unset_all 50000 74.54 µs/op
Benchmark Bitmap.Binary.new 20000 79.34 µs/op
Benchmark Bitmap.Binary.set? 20000 90.18 µs/op
Benchmark Bitmap.Binary.at 20000 99.70 µs/op
Benchmark Bitmap.Binary.toggle 10000 169.97 µs/op
Benchmark Bitmap.Binary.unset 10000 207.38 µs/op
Benchmark Bitmap.Binary.set 10000 208.58 µs/op
Benchmark Bitmap.Integer.set_all 10 111083.80 µs/op
Benchmark Bitmap.Binary.set_all 10 143833.10 µs/op
Benchmark Bitmap.Binary.to_string 1 80530194.00 µs/op
Benchmark Bitmap.Integer.to_string 1 89035291.00 µs/op
Benchmark Bitmap.Binary.toggle_all 1 451542225.00 µs/op
This project is available under MIT License.