在给定每个字符的可用字母列表的情况下获取单词列表时遇到问题（Python）

Question

I have a list of words that I would like to go through and remove any that don't fit my criteria.

The criteria is a list of lists of letters that are possible for each character.

letters = [['l','e'],['a','b','c'],['d','e','f']]
words = ['lab','lad','ebf','tem','abe','dan','lce']

The function I have written to try and solve this is:

def calc_words(letters,words):
    for w in words:
        for i in range(len(letters)):
          if w in words:
            for j in letters[i]:
              if w in words:
                if j != w[i]:
                    words.remove(w)
    return words

The output when I run the function calc_words(letters,words) should be ['lad', 'ebf', 'lce'] but is instead ['lad', 'tem', 'dan']

I can't figure out what is going on. I'm relatively new to Python, so if someone either knows what is going wrong with my function, or knows a different way to go about this, I would appreciate any input.

Answer 1

In general, it's good to avoid using one-letter variable names and reduce nesting as much as possible. Here's two implementations of calc_words() that should suit your needs:

letters = [['l','e'],['a','b','c'],['d','e','f']]
words = ['lab','lad','ebf','tem','abe','dan','lce']

def calc_words(letters, words):
    # Iterate over each word.
    # Assume that a word should be in the result
    # until we reach a letter that violates the
    # constraint set by the letters list.
    result = []
    for word in words:
        all_letters_match = True
        for index, letter in enumerate(word):
            if letter not in letters[index]:
                all_letters_match = False
                break
        if all_letters_match:
            result.append(word)

    return result

# Prints "['lad', 'ebf', 'lce']".
print(calc_words(letters, words))

There is a comment in the first definition that describes how it works. This is similar to your implementation, with some nesting removed and some improved naming (eg the if w in words check aren't necessary, because in each iteration of w , w takes on the value of an element from words ). I've tried to keep this solution as close to your original code.