# Functions and Methods

## Python Functions for Excel Column Conversion, Classification Model Evaluation, Precision, Recall, and Word Counts

Published on July 8, 2023 by Pradeepchandra Reddy S C

Tags: Python, Programming ### Introduction:

Python offers a wide range of functionalities and libraries for data analysis and manipulation. In this article, we explore four Python functions that address different aspects of data processing. We start by converting Excel column names to corresponding column numbers, evaluate a classification model using accuracy, precision, and recall metrics, and conclude by counting words of a specific length in a sentence. Throughout the process, I gained insights into fundamental concepts of Functions and Methods.

### Problem 1: Excel Column Name to Column Number Conversion

We begin with a function that converts an Excel column name (e.g., 'A', 'BD', 'AAA') to its corresponding column number. The function utilizes a dictionary and list comprehension to perform the conversion. By iterating through the characters in the column name from right to left and multiplying by ascending powers of 26, the function computes the column number. This example showcases Python's ability to handle mathematical operations and dictionary mapping efficiently.

### Problem 2: Classification Model Evaluation Metrics

Next, we tackle the evaluation of a classification model using accuracy, precision, and recall metrics. Given two lists of actual and predicted labels, we calculate the accuracy by comparing the number of correctly predicted labels to the total number of labels. To calculate precision and recall, we focus on a specific label (e.g., 'Cat' or 'Dog') and count the correctly predicted instances of that label divided by the predicted or actual counts, respectively. This example demonstrates how Python can be used to evaluate the performance of a classification model using various metrics.

### Problem 3: Precision and Recall Calculation for a Given Label

Building on the previous problem, we create a function that calculates precision and recall for a specific input label. By counting the predicted and actual occurrences of the label in the lists, we calculate the number of correctly predicted labels. Dividing this count by the predicted or actual counts yields precision and recall, respectively. This example showcases Python's ability to create reusable functions and perform calculations based on user-defined inputs.

### Problem 4: Word Count for a Given Length in a Sentence

Lastly, we present a function that counts the occurrences of words with a specified length in a sentence. By splitting the sentence into a list of words and using list comprehension, we filter words based on their length. The function returns both the count and the list of words meeting the length criterion. This example demonstrates how Python can efficiently handle string manipulation, filtering, and list comprehension.

### Conclusion:

In this article, we explored four Python functions that address different data analysis challenges. From converting Excel column names to numbers and evaluating classification models to calculating precision, recall, and word counts, these functions highlight the versatility and power of Python in data processing tasks. Python's concise syntax, extensive libraries, and flexibility in handling diverse data types make it a valuable tool for data scientists and analysts. By leveraging Python's functionalities, users can efficiently manipulate, analyze, and derive insights from their data.