defmodule Multitool.Numbers do
@moduledoc """
The Numbers module holds helper functions for number operations
such as primes and factors
"""
@moduledoc since: "0.1.0"
import Multitool.Collections.ListOperations
def natural?(n) when is_number(n) and n < 0, do: false
@doc """
Evaluates if a number is greater than negative one and does not have a remainder
## Parameters
n: Integer to evaluate for naturalness
## Examples
iex> natural?(-5)
false
iex> natural?(7)
true
iex> natural?(7.5)
false
iex> natural?(7.0)
true
"""
@doc since: "0.3.1"
def natural?(n) when is_number(n), do: Kernel.trunc(n) == n
def trim_left(n) when is_integer(n) and n < 0, do: trim_left(n * -1) * -1
def trim_left(n) when is_integer(n) and n in 0..10, do: 0
@doc """
Returns the given number without the leftmost digit
When the given number is between negative nine and nine, zero is returned
## Parameters
n: Integer to trim the leftmost digit off of
## Examples
iex> trim_left(57689)
7689
iex> trim_left(7)
0
iex> trim_left(-56788)
-6788
iex> trim_left(-3)
0
"""
@doc since: "0.3.1"
def trim_left(n) when is_integer(n) do
places = :math.log10(n) |> Kernel.trunc()
powers = :math.pow(10, places) |> Kernel.trunc()
rem(n, powers)
end
def trim_right(n) when is_integer(n) and n < 0, do: trim_right(n * -1) * -1
def trim_right(n) when is_integer(n) and n in 0..9, do: 0
@doc """
Returns the given number without the rightmost digit
When the given number is between negative nine and nine, zero is returned
## Parameters
n: Integer to trim the rightmost digit off of
## Examples
iex> trim_right(57689)
5768
iex> trim_right(7)
0
iex> trim_right(-56788)
-5678
iex> trim_right(-3)
0
"""
@doc since: "0.3.1"
def trim_right(n) when is_integer(n), do: div(n, 10)
def cycle(0), do: 0
@doc """
Shifts all digits one place to the right, bringing the right most digit to the leftmost position
If the operation of bringing the rightmost digit to the leftmost position would result in the leading number
of the resulting integer being a zero, the digits are repeatedly shifted until a zero is not in the
leftmost position
## Parameters
n: The integer to cycle
## Examples
iex> cycle(57)
75
iex> cycle(-57)
-75
iex> cycle(190)
901
"""
@doc since: "0.3.1"
def cycle(n) when is_integer(n) do
Integer.digits(n) |> shift() |> _cycle() |> Integer.undigits()
end
defp _cycle([0 | _tail] = digits), do: _cycle(shift(digits))
defp _cycle(digits), do: digits
def cycle(n, 0) when is_integer(n), do: n
@doc """
Shifts all digits to the right, repeated a given number of times.
This operation operates the same as `cycle/1` regarding leading zeroes
If the operation of bringing the rightmost digit to the leftmost position would result in the leading number
of the resulting integer being a zero, the digits are repeatedly shifted until a zero is not in the
leftmost position
## Parameters
n: The integer to cycle
c: The amount of times to apply the cycle operation
## Examples
iex> cycle(57, 1)
75
iex> cycle(-57, 2)
-57
iex> cycle(190, 2)
190
"""
@doc since: "0.3.1"
def cycle(n, c) do
n |> cycle() |> cycle(c - 1)
end
@doc """
Generates a MapSet of numbers resulting from cycling the given number so each digit is in each position once
This operation operates the same as `cycle/1` regarding leading zeroes
If the operation of bringing the rightmost digit to the leftmost position would result in the leading number
of the resulting integer being a zero, the digits are repeatedly shifted until a zero is not in the
leftmost position
## Parameters
n: The integer to generate cycles of
## Examples
iex> cycles(123) |> MapSet.to_list()
[123, 231, 312]
iex> cycles(-57) |> MapSet.to_list()
[-75, -57]
"""
@doc since: "0.3.1"
def cycles(n) when is_integer(n) do
cycles = abs(n) |> :math.log10() |> trunc()
_cycles(n, cycles) |> MapSet.new()
end
defp _cycles(n, 0), do: [n]
defp _cycles(n, c) do
[n | _cycles(cycle(n), c - 1)]
end
end
