bitmap v0.1.6 → Overview → Bitmap

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

Source

Summary

at(bitmap, index)

Returns the bit value at index in the bitmap
new(argument)

Creates and returns a bitmap of size corresponding to the argument passed
set(bitmap, index)

Sets the bit at index in the bitmap and returns the new bitmap
set?(bitmap, index)

Returns a boolean representing whether the bit at position index is set or not
set_all(bitmap)

Set all bits in the bitmap and returns a new bitmap
toggle(bitmap, index)

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
toggle_all(bitmap)

Toggles all bits in the bitmap and returns a new bitmap
unset(bitmap, index)

Unsets the bit at index in the bitmap and returns the new bitmap
unset_all(bitmap)

Unsets all bits in the bitmap and returns a new bitmap

Functions

at(bitmap, index)
(function) # ↑

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
Source
new(argument)
(function) # ↑

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)>>
Source
set(bitmap, index)
(function) # ↑

Sets the bit at index in the bitmap and returns the new bitmap

Index can also have a value :all in which case all bits will be set like in set_all

Examples

iex> Bitmap.set(Bitmap.new(5), 3)
<<2::size(5)>>
iex> Bitmap.set(Bitmap.new(1..10), 2)
<<32, 0::size(2)>>
Source
set?(bitmap, index)
(function) # ↑

Returns a boolean representing whether the bit at position index is set or not

Examples

iex> bm = Bitmap.new(5) |> Bitmap.set(1) |> Bitmap.set(3)
iex> Bitmap.set?(bm, 1)
true
iex> Bitmap.set?(bm, 4)
false
Source
set_all(bitmap)
(function) # ↑

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)>>
Source
toggle(bitmap, index)
(function) # ↑

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

Index can also have a value :all in which case all bits will be toggled like in toggle_all

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)>>
Source
toggle_all(bitmap)
(function) # ↑

Toggles all bits in the bitmap and returns a new bitmap

Examples

iex> bm = Bitmap.new(10) |> Bitmap.set(4) |> Bitmap.set(8)
iex> Bitmap.toggle_all(bm)
<<247, 1::size(2)>>
Source
unset(bitmap, index)
(function) # ↑

Unsets the bit at index in the bitmap and returns the new bitmap.

Index can also have a value :all in which case all bits will be unset like in unset_all

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)>>
Source
unset_all(bitmap)
(function) # ↑

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)>>
Source