sort_nat: Natural Order Sort

Natural order sorting sorts strings containing digits in a way such that the numerical value of the digits is taken into account. It is especially useful for sorting file names containing index numbers with different numbers of digits. Often, people will use leading zeros to get the right sort order, but with this function you don't have to do that. For example, with input of

{'file1.txt','file2.txt','file10.txt'}

a normal sort will give you

{'file1.txt','file10.txt','file2.txt'}

whereas, sort_nat will give you

{'file1.txt','file2.txt','file10.txt'}