Find different words from one word

Given a list of words, for example with

words = set(line.strip().lower() for line in open('/usr/share/dict/words'))

you can build and index of «wildcarded» words, where you replace each character of the word with a wildcard (say «?»), so that for example «gat» and «fat» both get indexed to «?at»:

def wildcard(s, idx):
    return s[:idx] + '?' + s[idx+1:]

def wildcarded(s):
    for idx in xrange(len(s)):
        yield wildcard(s, idx)

# list(wildcarded('cat')) returns ['?at', 'c?t', 'ca?']

from collections import defaultdict
index = defaultdict(list)

for word in words:
    for w in wildcarded(word):
        index[w].append(word)

Now if you want to look for all the words that differ by one letter from «cat», just look for «?at», «c?t» and «ca?» and concatenate the results:

def near_words(word):
    ret = []
    for w in wildcarded(word):
        ret += index[w]
    return ret

print near_words('cat')
# outputs ['cat', 'bat', 'zat', 'jat', 'kat', 'rat', 'sat', 'pat', 'hat', 'oat', 'gat', 'vat', 'nat', 'fat', 'lat', 'wat', 'eat', 'yat', 'mat', 'tat', 'cat', 'cut', 'cot', 'cit', 'cay', 'car', 'cap', 'caw', 'cat', 'can', 'cam', 'cal', 'cad', 'cab', 'cag']
print near_words('stack')
# outputs ['stack', 'stack', 'smack', 'spack', 'slack', 'snack', 'shack', 'swack', 'stuck', 'stack', 'stick', 'stock', 'stank', 'stack', 'stark', 'stauk', 'stalk', 'stack']

If the maximum word length is L and the number of words is N, the index is made of O(NL) pointers, while the lookup algorithm runs in time O(L + number of results).

If you want to look for all the words that differ by K letters instead of 1 this approach doesn’t generalize well, but it is a very hard problem in full generality (it is the problem of finding neighbors in Hamming spaces).

Enter Letters and word bank below to use the word search solver

Stuck on a word search? Have you spent what feels like hours hunting for that one missing word to solve your puzzle? You’re in the right place: welcome to our Word Search Solver! Whether you need help solving a school assignment or just want to finish your puzzle before you lose your sanity, you can use our tool to quickly and easily find the missing words you’re looking for.

How To Use the Word Search Solver

1. Create your board: In the ‘Create Board’ box, type all the letters that appear on your board in the order they appear. Don’t forget to hit return between lines to ensure correct formatting. The board preview will automatically update as you type, so you can check to make sure the board is accurate as you go.
2. Enter words to find: If you’re looking for particular words in your search, you can enter them into the ‘Find these words’ box. When searching for multiple words, make sure to separate them using commas. Spaces aren’t necessary between words.
3. Set searching parameters: Our tool allows you to search only for specific words or to search for any word found in the dictionary. If you don’t have specific words you want to search for, set the parameter to ‘Dictionary only.’ Even if you are looking for specific words, it can be fun to see all the words that appear in your search, whether intentionally included or not!

Tips for Solving Word Searches

This section describes some tips on how to improve at word search puzzles.

Scan each row for key letters.

Although this is not the quickest way to solve a puzzle, it is likely the most thorough when you are stuck. Instead of randomly searching the board, start at the top left corner of the board and, row-by-row, scan for key letters or letter combinations. For instance, if one of the words you are searching for is ‘puzzle’, scan the board for the letter ‘P’ or ‘Z’. This methodical approach can help ensure you don’t miss anything hiding in plain sight!

Look for the longest words first.

If your board includes long words, try searching for those first. They’re often easy to find, because they take up a significant amount of space on the board — and they can help you narrow down available search areas for other, shorter words.

Make sure you know your board’s rules.

Depending on the word search, there might be different rules about how words can appear on the board. For instance, some word searches might allow for words to be placed diagonally and backwards across the board, while others may not. Make sure you know your board’s rules, so you’re not missing out on different ways the word could appear.

Look for key two-letter combinations.

Sometimes, if a word contains a lot of common letters, that word can be harder to find on the board. To narrow down your search, try to find a unique two-letter combination within the word that you can search for. These combinations will be less likely to appear randomly on your board, and can significantly narrow down your search time. For instance, if you’re searching for the word ‘Aubergine,’ you might look for the ‘AU’ letter combination instead of only searching for ‘A’s.

Scan the board backwards, or turn it upside down.

If you find yourself stumped, a good way to change your perspective is to scan the board backwards or upside down. For instance, starting at the bottom right corner and looking for key letters might help you find something you missed when scanning from left to right. Similarly, physically turning the board upside down might help you notice patterns on the board that you previously missed.

Use your finger or a pen to keep your place.

It can be easy to lose yourself in all those letters. When you’re scanning the board, keep your place with your finger or a pointing device in order to ensure you don’t inadvertently skip any lines or letters.

Where to Find Word Searches of All Difficulty Levels

The Word Finder has our own word search puzzles to browse and play. Whether you’re a teacher looking for a way to entertain their students, or a hobbyist who just likes to keep their mind sharp, we have word searches for all different ages, topics, and difficulty levels. For many of our puzzles, you can even customize the difficulty level for different players. For instance, you can generate an ‘easy’ Taylor Swift word search for one child, and a ‘hard’ Taylor Swift word search for another, so they can work on the similar tasks customized to their abilities. If you’re looking for more of a challenge, we also have a unique ‘brutal’ setting for our word searches, which creates puzzles even the most skilled searcher would struggle to solve. We also have a tool that will allow you to make your own custom word search puzzle. These can be great for gifts, parties, or even the classroom. Word search puzzles have been around for a long time, and it’s fun to be able to create your own!

Feedback for Word Search Solver

What do you think about our Word Search Solver? Was this tool useful for you, or are there features you’d like to add? We’d love to hear from you! Reach out using the ‘Contact Us’ page linked below to share your suggestions. Also be sure to check out our new wordle solver for the popular new word game!

I had a long list (57 pages!) of Latin species names, sorted into alphabetical order. I’d separated the words so that there was only one word on each line. My next task was to go through and remove all the duplicates (i.e. a word immediately followed by the same word) so I could add the final list to my custom dictionary for species in Microsoft Word. I started doing it manually—it’s easy enough to find duplicates when the words are familiar, but for Latin words, my brain just wasn’t coping well and I was missing subtle differences like a single or double ‘i’ at the end of a word. There had to be a better way…

And there is! Good old Dr Google came to the rescue, and with a bit of fiddling to suit my circumstances (one word on each line), I got a wildcard find and replace routine to find the duplicates.

NOTE: DO NOT do a ‘replace all’ with this, in case Word makes unwanted changes. In my case it didn’t treat the second word as a whole word for matching purposes (e.g. it thought banksi, banksia, and banksii were duplicates). Even though I had to skip some of these, it was still worth it to automate much of the process. Another caveat—if you have several lines of the same word, each pair will be found, but you’ll have to run the find several times to get them all. Much better to move your cursor into Word and delete the excess multiple duplicates when you find them. You may still have to do a couple of passes over the document, but the heavy lifting will have been done for you.

Here’s what I did to get it work:

1. Press Ctrl+H to open the Find and Replace window.
2. Click More, then select the Use Wildcards checkbox.
3. In the Find What field, type (<*>)^0131 (there are no spaces in this string).
4. In the Replace With field, type 1 (there are no spaces in this string either).
5. Click Find Next.
6. When a pair of matching whole words is found, click Replace. NOTE: If the second word is only a partial match for the first word, click Find Next.
7. Repeat steps 5 and 6 until you’re satisfied you’ve found them all.

How this works:

• (<*>) is the first element (later represented by 1) of the find. The angle brackets specify the start and end of a word, and the ‘word’ is anything (represented by the *). In other words, you’re looking for a whole ‘word’ of any length and made up of any characters (including numbers).
• ^013 is the paragraph marker at the end of the line. In my situation, each word was on its own line with a paragraph mark at the end of the line. If you don’t have this situation, leave this out and replace it with a space (two repeated words in the same line are separated by a space). NOTE: Normally you can find a paragraph mark in a Find with ^p, but not with a wildcard Find—you have to use ^013.
• 1 is the first element. In the Find, it means the duplicate of whatever was found by (<*>); in the Replace, it means replace the duplicated word with the first word found.

I have a list of words in English. My aim is to find all pairs of words that differ by exactly one letter (i.e. edit distance is 1). For instance: PAY-PLAY, WARM-ARM, WORD-WORK.

The naive algorithm is to compare every word with all other words in the list. I’ve improved it by noticing that if one word is two letters or more longer than the other word, then they can’t differ by exactly one letter. So I first sort the word list by length, then compare every word with words of the same length or longer by one letter.

This is my code:

import nltk

words = ['a', 'abide', 'ability', 'able', 'about', 'above', ...]
words.sort(key=len)

pairs = []

for i, w1 in enumerate(words):
  for j, w2 in enumerate(words[i+1:]):
    if len(w2) - len(w1) > 1:
      break
    if nltk.edit_distance(w1, w2) == 1:
      pairs.append((w1, w2))

Can it be improved further? It should scale well with the size of word list (I plan to run it with a list of tens of thousands of words).