Soundex in Python

Soundex in Python

  1. Introduction to soundex in Python
  2. Use soundex in Python
  3. Things the soundex Function Ignores
  4. Rules of soundex in Python
  5. Conclusion

The soundex function for Python is a function that converts a string of text into a Soundex code. It is helpful for indexing names in databases or finding similar ones.

The Soundex code for a name is based on how it sounds, not how it is spelled. It is a handy tool for comparing words pronounced differently but with the exact spelling.

It is beneficial when searching for names in databases.

Introduction to soundex in Python

The soundex function is a simple phonetic algorithm used to encode strings. The algorithm is designed to produce codes similar to those produced by the Soundex system.

The function is written in Python and can be easily implemented in any Python project. The soundex function takes a string as input and returns a code based on the sound of the string.

It assigns a code to each word based on how it is pronounced, so words pronounced differently but with the same code are considered equivalent. It can be a big help when searching for names that may be spelled differently but are pronounced the same.

It can be useful when you compare words that are pronounced differently but have the exact spelling. For example, cat and bat have the same soundex code.

Use soundex in Python

The soundex function in Python takes a string as an input and outputs a code representing the sound of the string. The code is based on how the string sounds, not spelling.

It makes it helpful in matching names pronounced differently but with the same sound.

The soundex process is a means of indexing names by sound. It is a simple phonetic algorithm for indexing words by sound, as pronounced in English.

The goal is to produce a Soundex code that captures the name’s essential sound while disregarding spelling differences.

To use the soundex function, you first need to import the module that contains it; then, you can call the function with a string as an argument. The function will return the Soundex code for the string.

The Soundex code is a four-digit code used to represent a name’s pronunciation. The code is derived from the first letter of the name, followed by three numbers representing the name’s three consonants.

The code is designed to be pronounceable so that words with similar pronunciations will have the same code.

Example Code:

# First, we will create a Soundex generator function
def soundex_generator(token):

    # Now Convert the word to upper
    token = token.upper()
    soundex = ""

    # Will Retain the First Letter
    soundex += token[0]

    # Now, will Create a dictionary that maps
    # letters to respective Soundex
    # codes. Vowels and 'H', 'W' and
    # 'Y' will be represented by '.'

    dictionary = {"BFPV": "1", "CGJKQSXZ": "2",
                  "DT": "3",
                  "L": "4", "MN": "5", "R": "6",
                  "AEIOUHWY": "."}

    # Now encode as per the dictionary
    for char in token[1:]:
        for key in dictionary.keys():
            if char in key:
                code = dictionary[key]
                if code != '.':
                    if code != soundex[-1]:
                        soundex += code

    # Trim or Pad to make Soundex a
    # 7-character code
    soundex = soundex[:7].ljust(7, "0")
    return soundex

# driver code



Things the soundex Function Ignores

The soundex process ignores non-alphabetic characters in a name, so punctuation and spaces are not considered.

In addition, soundex only codes the first letter of a surname if it is a consonant, so surnames that begin with vowels are not coded.

Finally, soundex codes names according to their pronunciation, so variants of the same name that are pronounced differently (such as Smith and Smyth) will have different codes.

Rules of soundex in Python

However, the Soundex process has several rules.

  1. First, it is not well-suited for indexing names from languages other than English since the soundex code is based on English phonetics.
  2. Second, the soundex code for a given name can vary depending on the English dialect used. For instance, the name Smith would be coded as S530 in General American English but as S520 in Southern English.
  3. Third, the Soundex process can sometimes produce ambiguous results, especially when two or more names have the same soundex code. For instance, the names Smith and Smythe both have the soundex code S530, making it challenging to find a specific name when using a Soundex-based index.
  4. Fourth, the Soundex process is not very effective at indexing names that are pronounced differently than spelled. For instance, the name Stevenson is pronounced STEH-ven-son, but it would be coded as S315 based on its spelling, making it challenging to find a name when using a Soundex-based index.

Overall, the Soundex process is a simple and effective means of indexing names by sound. However, it has several limitations that should be considered when using it.


To conclude the article on soundex in Python, we’ve discussed the working and rules of soundex. Furthermore, we have discussed a practical example demonstrating the working of soundex in Python.

Zeeshan Afridi avatar Zeeshan Afridi avatar

Zeeshan is a detail oriented software engineer that helps companies and individuals make their lives and easier with software solutions.