README.md

Digits

A package for integer digit computations.

Based on julias digits() function.

Installation / Testing

You can install the package by typing:

Pkg.add("Digits")
using Digits

or clone the latest version directly from the repo:

Pkg.clone("https://github.com/greenflash1357/Digits.jl.git")
using Digits

Function Overview

reversedigits(n)/reversedigits!(l)

Returns the digits of n in reversed order, i.e. reversedigits(n) == undigit(reverse!(digits(n))). For a list of digits this is equivalent to reverse() and reverse!().

undigit(A [, base])

The inverse function to julias digits(). Accepting a vector of integers where more significant digits are at higher indexes, according to digits() and a base. Default is 10.

digithist(n)

Creates a digit histogram for a given number. The result is a 1-dimensional 10-element array containing the count of each digit. The first element contains the count of 0, while the last represents the count of 9.

contains(a,b)

Checks whether a or b is part of the other, e.g. contains(1356,35) will result in true.

startswith(a,b) / endswith(a,b)

Checks wether a or b is the first/last part of the other, e.g. startswith(1356,1), startswith(32,3236), endswith(31,9831) will all return true.

isanagram(a,b)

Returns true if a and b are valid permutations of their digits.

ispalindrome(n)

Returns true if n is a palindromic number.

crop(n,i)

Cuts off i digits from n. If i is positive the first (most significant) digits are cropped. If i is negative the last digits are cut off.

combine(a,b)

Return the combination of a and b, similar to a string concatenation, e.g. combine(13,56) -> 1356.

crosssum(n)

Calculates the cross sum over n.

select(n,idx)

Returns the digits of n with index idx. idx can be an array or range, e.g. select(64247,[2:4]) -> 424

replace(n,idx,vals) / replace!(l,idx,vals)

Replaces the digits of n with index idx by the values in vals. vals has to be same size as idx. For arrays of digits there is also an inplace version of replace. Example: replace(6215,[2,4],[8,7]) -> 6817

replace(n,olddigit,newdigit) / replace!(l,olddigit,newdigit)

Replaces the all digits of n with value olddigit with newdigit. There is also an inplace operation for arrays of digits. Example: replace(1363,3,9) -> 1969

digitroot(n) / digitroot(l)

Computes the digital root of n. That is the iterative sum of the digits until the result is a single digit number. digitroot(13548) -> 3

Notes

• Most functions accept an array of digits aswell as an integer as input.
• For most of the array methods there exists an inplace operation.
• This package should also work for negative integers, but this can become tricky. Take a closer look at the digit representation of negative integers. digits(-135) -> [-5, -3, -1].