#!/usr/bin/env python

import sys

from the_semantic_db_code import *
from the_semantic_db_functions import *
from the_semantic_db_processor import *

C = context_list("play with natural sort")

# http://stackoverflow.com/questions/4836710/does-python-have-a-built-in-function-for-string-natural-sort

import re

def natural_sort(list, key=lambda s:s):
    """
    Sort the list into natural alphanumeric order.
    """
    def get_alphanum_key_func(key):
        convert = lambda text: int(text) if text.isdigit() else text 
        return lambda s: [convert(c) for c in re.split('([0-9]+)', key(s))]
    sort_key = get_alphanum_key_func(key)
#    list.sort(key=sort_key)
    return sorted(list,key=sort_key)

my_list = ['a1','a12','a13','a','a51','a6','a7','b7','b9','a8','a9','a10','a11','b1','b2','b3','b4']
natural_sort(my_list)
print(my_list)
sorted_list = natural_sort(my_list)
print(sorted_list)

sys.exit(0)
# buggy. I don't understand why.
def natural_sort(l): 
    convert = lambda text: int(text) if text.isdigit() else text.lower() 
    alphanum_key = lambda key: [ convert(c) for c in re.split('([0-9]+)', key) ] 
    return sorted(l, key = alphanum_key)

print(natural_sort['a1','b','c1'])