Develop an R code to classify classes using logit model and also calculate its accuray and precision using standard metrics
To implement a logistic regression model in R, you can follow these steps:
1. **Install and Load Necessary Libraries**: You may need the `dplyr` library for data manipulation and `caret` for model evaluation.
2. **Prepare the Data**: Load your dataset and preprocess it as needed.
3. **Split the Data**: Divide your data into a training and testing set.
4. **Fit the Logistic Regression Model**: Use the `glm` function to fit the model.
5. **Make Predictions**: Use the model to predict on the test set.
6. **Calculate Accuracy and Precision**: Use confusion matrix and other metrics.
Here's an example code snippet to illustrate the process:
```R
# Load necessary libraries
if (!require(dplyr)) install.packages('dplyr', dependencies=TRUE)
if (!require(caret)) install.packages('caret', dependencies=TRUE)
library(dplyr)
library(caret)
# Load dataset
# For example, we will use the iris dataset, but you would replace this with your dataset
data(iris)
# Convert Species to a binary class for easier logistic regression demonstration
iris$Species <- ifelse(iris$Species == "setosa", 1, 0)
# Split data into training and testing sets
set.seed(123) # for reproducibility
train_index <- createDataPartition(iris$Species, p = 0.7, list = FALSE)
train_data <- iris[train_index, ]
test_data <- iris[-train_index, ]
# Fit the logistic regression model
model <- glm(Species ~ Sepal.Length + Sepal.Width + Petal.Length + Petal.Width,
data = train_data, family = binomial)
# Summarize the model
summary(model)
# Make predictions on the test set
predicted_probs <- predict(model, newdata = test_data, type = "response")
predicted_classes <- ifelse(predicted_probs > 0.5, 1, 0)
# Create confusion matrix
confusion_matrix <- confusionMatrix(factor(predicted_classes), factor(test_data$Species))
# Print results
print(confusion_matrix)
# Calculate accuracy and precision
accuracy <- confusion_matrix$overall['Accuracy']
precision <- confusion_matrix$byClass['Precision']
# Print accuracy and precision
cat("Accuracy:", accuracy, "\n")
cat("Precision:", precision, "\n")
```
### Explanation of the Code:
- **Data Preparation**: This example uses the `iris` dataset and converts it to a binary classification problem (setosa vs. non-setosa).
- **Train-Test Split**: The data is split into 70% training and 30% testing using `createDataPartition`.
- **Model Fitting**: The `glm` function fits a logistic regression model.
- **Predictions**: The `predict` function generates probabilities, which are then converted to class labels based on a threshold (0.5).
- **Model Evaluation**: The results are summarized, and accuracy and precision are extracted from the confusion matrix.
### Note:
- Replace the dataset and variables as needed for your specific problem.
- Ensure to explore your data initially for preprocessing needs (handling missing values, scaling, etc.) and use appropriate evaluation metrics based on your specific classification problem (e.g., F1 score, AUC-ROC if it's a multi-class problem).