Let's say I have three words I want to sort:
- hello
- goodbye
- alex
And alphabetically it'd be sorted ascendingly as ["alex", "goodbye", "hello"]
. Is there a way to convert the string (limited to 100 characters)? For example, if I have:
['a', 'l', 'e', 'x']
And I use ord
to get the code for each list element:
[1, 12, 5, 24]
How would I create a number from that, that would also be smaller than, say, goodbye
?
CodePudding user response:
Use:
from operator import mul, pow
from itertools import repeat
LIMIT = 100
char_vals = [1, 12, 5, 24]
sum(map(mul, char_vals, map(pow, repeat(27), range(LIMIT - 1, -1, -1))))
Since you've bounded the length of the strings, you can think of each word as a base-27 number. 0 represents that the letter doesn't exist, 1 represents a
, 2 represents b
, etc.
Then, the numerical value of each word can be computed using the following polynomial:
i_1 * 27**99 i_2 * 27**98 ...
where char_vals = [i_1, i_2, ... i_{len(original_string)}]
(i.e. each i
is the integer value of the corresponding letter, and i
s that are past the end of the array correspond to zeroes).
CodePudding user response:
Just use map and a lambda function. Python "ord" doesn't work on lists, just characters.
# Original list
words = ["hello", "goodbye", "alex"]
# Ordinals
words = list(map(lambda word: ord(word[0]), words))
# To sort it:
words = sorted(words)
CodePudding user response:
If we limit the array to N characters, we could do something like this:
words = ["hello", "goodbye", "alex"]
LETTERS_IN_ALPHABET = 26
def num_from_string(s, max_length=10):
num = 0
for i, char in enumerate(s):
num = ord(char) * ((LETTERS_IN_ALPHABET 1) ** (max_length-i))
return num
sorted(words, key=num_from_string)
# ['alex', 'goodbye', 'hello']