bitmap v0.1.2 → 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

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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
toggle(bitmap, index)	Toggles the bit at `index` in the bitmap and returns the new bitmap
unset(bitmap, index)	Unsets the bit at `index` in the bitmap and returns the new bitmap

at(bitmap, index)

(function) # ↑

Returns the bit value at index in the bitmap

iex> bm = Bitmap.new(5)
iex> Bitmap.at(bm, 2)
0
iex> bm = Bitmap.set(bm, 2)
iex> Bitmap.at(bm, 2)
1

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new(argument)

(function) # ↑

Creates and returns a bitmap of size corresponding to the argument passed.

If argument is

Note: All bits are set to 0 by default

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)>>

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set(bitmap, index)

(function) # ↑

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

iex> Bitmap.set(Bitmap.new(5), 3)
<<2::size(5)>>
iex> Bitmap.set(Bitmap.new(1..10), 2)
<<32, 0::size(2)>>

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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

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)>>

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unset(bitmap, index)

(function) # ↑

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

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)>>

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