遍历字符串，仅返回某些字符。 蟒蛇

Question

I have a problem when creating a function that's supposed to first return lowercase letters, "_" and "." and then uppercase letters, " " and "|" in that order. My version seems to return numbers and special characters like <>@ too which I don't want it to do, It's only supposed to read through the input string once and I don't know if that's achieved with my code.

My code is:

def split_iterative(n):
    splitted_first = ""
    splitted_second = ""
    for i in n:
        if i == i.lower() or i == "_" or i == ".":
            splitted_first = splitted_first + i
        elif i == i.upper() or i == " " or i == "|":
            splitted_second = splitted_second + i
    return splitted_first + splitted_second

if I do s plit_iterative("'lMiED)teD5E,_hLAe;Nm,0@Dli&Eg ,#4aI?rN@T§&e7#4E #<(S0A?<)NT8<0'")) it returns "'li)te5,_he;m,0@li&g ,#4a?r@§&e7#4 #<(0?<)8<0'MEDDELANDEINTESANT" which is incorrect as it should eliminate all those special characters and numbers. How do I fix this? It should return ('lite_hemligare', 'MEDDELANDE INTE SANT')

Answer 1

You could try this:

def f(input_string):
    str1 = str2 = ""
    for character in input_string:
        if character.isalpha():
            if character.islower():
                str1 += character
            else:
                str2 += character
        elif character in "_.":
            str1 += character
        elif character in " |":
            str2 += character
    return str1, str2

Output:

>>> input_string = "'lMiED)teD5E,_hLAe;Nm,0@Dli&Eg ,#4aI?rN@T§&e7#4E #<(S0A?<)NT8<0'"
>>> 
>>> print f(input_string)
('lite_hemligare', 'MEDDELANDE INTE SANT')
>>> 

Answer 2

This is because you are iterating through a string. The lowercase of the special characters is the same as the character. ie. '#'.lower() == '#' . hence it'll return '#' and all other special characters. you should explicitly check for alphabets using the isalpha() method on strings. (i.isalpha() and i.lower() == i) or i == '_' or i == '.'

Answer 3

You can use ASCII values for the filtering of characters:

def split_iterative(n):
    splitted_first = ""
    splitted_second = ""
    for i in n:
        if ord(i) in range(97,122) or i == "_" or i == ".":
            splitted_first = splitted_first + i
        elif ord(i) in range(65,90) or i == " " or i == "|":
            splitted_second = splitted_second + i
    return (splitted_first , splitted_second)

Answer 4

First, to make it return a list don't return the concatenated string but a list

Second, you are not checking or filtering out the characters, one way would be by checking if the character is a letter using isalpha() method

something like this:

def split_iterative(n):
splitted_first = ""
splitted_second = ""
for i in n:
    if (i.isalpha() and i == i.lower()) or i == "_" or i == ".":
        splitted_first = splitted_first + i
    elif (i.isalpha() and i == i.upper()) or i == " " or i == "|":
        splitted_second = splitted_second + i
#returns a list you can make it a variable if you need
return [splitted_first, splitted_second] 

Answer 5

You can make use of two lists while walking through characters of your text.

You can append lowercase, underscore, and stop characters to one list then uppercase, space and pipe characters to the other.

Finally return a tuple of each list joined as strings.

def splittext(txt):
  slug, uppercase_letters = [], []
  slug_symbols = {'_', '.'}
  uppercase_symbols = {' ', '|'}

  for letter in txt:
    if letter.islower() or letter in slug_symbols:
      slug.append(letter)
    if letter.isupper() or letter in uppercase_symbols:
      uppercase_letters.append(letter)

  return ''.join(slug), ''.join(uppercase_letters)


txt="'lMiED)teD5E,_hLAe;Nm,0@Dli&Eg ,#4aI?rN@T§&e7#4E #<(S0A?<)NT8<0'"
assert splittext(txt) == ("lite_hemligare", "MEDDELANDE INTE SANT")