# Levenshtein Distance in Python: Troubleshooting Installation Errors on Windows

For Python developers, the Levenshtein distance package is one of the most valuable tools for text analysis, comparison, and natural language processing. The Levenshtein distance algorithm is indispensable because it is used in many real-life applications such as bioinformatics, speech recognition and spell checks.

The Levenshtein distance is a metric used to calculate the difference between two sequences of characters. The package in Python is the same name and is used to calculate distances easily. Simply put, it is the minimum number of single-character edits required to transform one word into another.

However, installing this package is sometimes problematic for users with a different configuration in their system. In this article, we will troubleshoot the problem often encountered when installing this package with pip, “Can’t install Levenshtein distance package on Windows Python 3.5”.

The Levenshtein distance is a metric used to calculate the difference between two sequences of characters, representing the minimum number of single-character edits required to transform one word into another. In Python, the Levenshtein distance package simplifies the implementation of this algorithm, making it valuable for text analysis, comparison, and natural language processing tasks. However, installing the package on Windows Python 3.5 may encounter errors due to missing dependencies, compatibility issues, or the absence of Microsoft Visual C++ build tools. To resolve these issues, users can install Microsoft Visual C++ tools, download wheel files separately, upgrade or downgrade Python versions, or update their pip version.

## Implementing Levenshtein Distance Manually

Manually, by defining a function we can also calculate the difference between two sequences of characters and compute the Levenshtein distance between them. In this section, we will look at the code of implementing it manually and then at the Levenshtein distance function to observe how easily we can call the function and it will do all the work for us.

To manually implement the algorithm, run the following code:

```def levenshtein_distance(str1, str2):
"""Calculating the Levenshtein distance between two strings."""
n_m = [[0 for j in range(len(str2) + 1)] for i in range(len(str1) + 1)]
for i in range(len(str1) + 1):
n_m[i][0] = i
for j in range(len(str2) + 1):
n_m[0][j] = j
for i in range(1, len(str1) + 1):
for j in range(1, len(str2) + 1):
if str1[i - 1] == str2[j - 1]:
cost = 0
else:
cost = 1
n_m[i][j] = min(n_m[i - 1][j] + 1, n_m[i][j - 1] + 1, n_m[i - 1][j - 1] + cost)
return n_m[-1][-1]

# Example usage
str1 = "kitten"
str2 = "sitting"
distance = levenshtein_distance(str1, str2)
print(f"Levenshtein distance between '{str1}' and '{str2}': {distance}")
```

In the above code, we have defined a function that calculates the distance between str1 and str2: kitten and sitting. The output is:

```Levenshtein distance between 'kitten' and 'sitting': 3
```

Now, we can see how when we use the Levenshtein package, the code becomes extremely compact, and the same thing happens in about 5 to 6 lines of code. You can install the package by running this line of code in your command prompt `pip install Levenshtein` .

```from Levenshtein import distance

# Example usage
str1 = "kitten"
str2 = "sitting"

# Calculate Levenshtein distance using the package
distance = distance(str1, str2)

print(f"Levenshtein distance between '{str1}' and '{str2}': {distance}")
```

The output of the above code will also be the same as given below:

```Levenshtein distance between 'kitten' and 'sitting': 3
```

Suggested: Fix CryptographyDeprecationWarning in Python 3.6 EOL.

## Possible Causes of the Error

Some of the possible causes of the error, “Can’t install Levenshtein distance package on Windows Python 3.5” are:

• Absence of dependencies or wheel files: Wheel files are Python installation files automatically downloaded when a package is installed to provide essential building blocks for faster installation and proper module functioning. The absence of the required files can result in this problem.
• Compatibility issues: Another major reason for this error is that the package version is incompatible with the Python version installed on your computer or the Pip version used to install the package is outdated and needs an update.
• Absence of Microsoft Visual C++ build tools: Since this error is mostly encountered in Windows, one of the main reasons could be the missing Microsoft Visual C++ tool, which is essential for compiling Python-Levenshtein. When this C compiler is missing, it is not possible for the package to compile its code.

The error message pops up as follows:

```ERROR: Could not find a version that satisfies the requirement python-Levenshtein
```

## Solutions for Solving the Error

During the installation using pip, many users face this error. Some of the common causes are:

• Installing Microsoft Visual C++ Tools.

Since Microsoft Visual C++ tools are essential for the compilation of the Python-Levenshtein package, it is advisable to download and install it on your system. Ensure you download the most recent or compatible version with your system’s Python environment. You can visit the official site to download Microsoft Visual C++. Ensure you include build tools during installation because it is crucial for compiling Python packages. After installation make sure to restart the computer.

There are wheel files separately available online that you can download according to your Python version and install in your system. This will bypass the need to depend on automatic installations and rather you will be able to track the progress of the download manually.

```pip install python-Levenshtein-wheels
```

In this fix, uninstall your previously installed Python version(that is 3.5 or if you have any other version), and then reinstall another different version (the most updated one is always recommended) and then install the Levenshtein package again making sure that all the dependencies are being installed at your preferred location. The link to download Python is here.

```pip install --upgrade pip