Bitmap
Contains functions to create and work with a bitmap
Bitmaps are also known as bit arrays, bit sets and is a fast space efficient data structure for lookups
The module has been designed to be pipe-friendly, so pipe ‘em up
Summary
at(bitmap, index) | Returns the bit value at |
new(argument) | Creates and returns a bitmap of size corresponding to the |
set(bitmap, index) | Sets the bit at |
set_all(bitmap) | Set all bits in the bitmap and returns a new bitmap |
toggle(bitmap, index) | Toggles the bit at |
unset(bitmap, index) | Unsets the bit at |
unset_all(bitmap) | Unsets all bits in the bitmap and returns a new bitmap |
Functions
Returns the bit value at index
in the bitmap
Examples
iex> bm = Bitmap.new(5)
iex> Bitmap.at(bm, 2)
0
iex> bm = Bitmap.set(bm, 2)
iex> Bitmap.at(bm, 2)
1
Creates and returns a bitmap of size corresponding to the argument
passed.
If argument
is
- integer, size of bitmap is equal to the
argument
- range, size of bitmap is equal to the length of
argument
- list, size of bitmap is equal to the length of
argument
Note: All bits are set to 0 by default
Examples
iex> Bitmap.new(400)
<<0::size(400)>>
iex> Bitmap.new([1,2,3,4,5])
<<0::size(5)>>
iex> Bitmap.new(1..25)
<<0::size(25)>>
Sets the bit at index
in the bitmap and returns the new bitmap
Examples
iex> Bitmap.set(Bitmap.new(5), 3)
<<2::size(5)>>
iex> Bitmap.set(Bitmap.new(1..10), 2)
<<32, 0::size(2)>>
Set all bits in the bitmap and returns a new bitmap
Examples
iex> Bitmap.set_all(Bitmap.new(10))
<<255, 3::size(2)>>
iex> Bitmap.set_all(Bitmap.new(100))
<<255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 15::size(4)>>
Toggles the bit at index
in the bitmap and returns the new bitmap.
i.e. it sets the bit to 1 if it was 0 or sets the bit to 0 if it was 1
Examples
iex> bm = Bitmap.new(10) |> Bitmap.set(4) |> Bitmap.set(8)
iex> Bitmap.toggle(bm, 3)
<<24, 2::size(2)>>
iex> Bitmap.toggle(bm, 6)
<<10, 2::size(2)>>
Unsets the bit at index
in the bitmap and returns the new bitmap
Examples
iex> bm = Bitmap.new(10) |> Bitmap.set(4) |> Bitmap.set(8)
iex> Bitmap.unset(bm, 4)
<<0, 2::size(2)>>
iex> Bitmap.unset(bm, 8)
<<8, 0::size(2)>>
Unsets all bits in the bitmap and returns a new bitmap
Examples
iex> bm = Bitmap.new(10) |> Bitmap.set(4) |> Bitmap.set(8)
iex> Bitmap.unset_all(bm)
<<0, 0::size(2)>>