Words in a list with consecutively repeated letters

Question

Right now I have a list of for example

data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff']  

I want to remove the words with the repeated letters, in which I want to remove the words

'aa','aac','bbb','bcca','ffffff'

Maybe import re?

Answer 1

The original version of this question wanted to drop words that consist entirely of repetitions of a single character. An efficient way to do this is to use sets. We convert each word to a set, and if it consists of only a single character the length of that set will be 1. If that's the case, we can drop that word, unless the original word consisted of a single character.

data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff'] 
newdata = [s for s in data if len(s) == 1 or len(set(s)) != 1]
print(newdata)

output

['dog', 'cat', 'a', 'aac', 'bcca']

---

Here's code for the new version of your question, where you want to drop words that contain any repeated characters. This one's simpler, because we don't need to make a special test for one-character words..

data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff'] 
newdata = [s for s in data if len(set(s)) == len(s)]
print(newdata)

output

['dog', 'cat', 'a']

---

If the repetitions have to be consecutive, we can handle that using groupby.

from itertools import groupby

data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff', 'abab', 'wow'] 
newdata = [s for s in data if max(len(list(g)) for _, g in groupby(s)) == 1]
print(newdata)

output

['dog', 'cat', 'a', 'abab', 'wow']

Answer 2

Thanks to this thread: Regex to determine if string is a single repeating character

Here is the re version, but I would stick to PM2 ring and Tameem's solutions if the task was as simple as this:

import re
data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff']  
[i for i in data if not re.search(r'^(.)\1+$', i)]

Output

['dog', 'cat', 'a', 'aac', 'bcca']

And the other:

import re
data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff']  
[i for i in data if not re.search(r'((\w)\2{1,})', i)]

Output

['dog', 'cat', 'a']

Answer 3

Loop is the way to go. Forget about sets so far as they do not work for words with repetitive letters.

Here is a method you can use to determine if word is valid in a single loop:

def is_valid(word):
    last_char = None
    for i in word:
        if i == last_char:
            return False

        last_char = i

    return True

Example

In [28]: is_valid('dogo')
Out[28]: True

In [29]: is_valid('doo')
Out[29]: False

Answer 4

Here's a way to check if there are consecutive repeated characters:

def has_consecutive_repeated_letters(word):
    return any(c1 == c2 for c1, c2 in zip(word, word[1:]))

You can then use a list comprehension to filter your list:

words = ['dog','cat','a','aa','aac','bbb','bcca','ffffff', 'abab', 'wow']
[word for word in words if not has_consecutive_repeated_letters(word)]
# ['dog', 'cat', 'a', 'abab', 'wow']

Answer 5

One line is all it takes :)

data = ['dog','cat','a','aa','aac','bbb','bcca','ffffff']  
data =  [value for value in data if(len(set(value))!=1 or len(value) ==1)]
print(data)

Output

['dog', 'cat', 'a', 'aac', 'bcca']