In this article, we will explore how to calculate mean squared error (MSE) in Python with the help of writing patterns. We will go through the basic concept of MSE, its importance, and how to implement it in Python programming language.

MSE, Python, programming, mean squared error, writing patterns

## Introduction to MSE and Writing Patterns

Mean Squared Error (MSE) is a popular method used to evaluate the performance of regression models. It is the average of the squared differences between the predicted and actual values. In other words, it measures how well the model fits the data. MSE is an important metric in machine learning and is often used to compare different models.

Writing patterns are a useful tool when working with machine learning algorithms. They help in organizing the code and making it more readable. By following a writing pattern, we can ensure that the code is consistent and easy to understand. In this article, we will use a writing pattern to calculate MSE in Python.

## Importing Required Libraries

To calculate MSE in Python, we need to import the required libraries. We will use the numpy and pandas libraries to load and manipulate the dataset. We will also use the scikit-learn library to split the dataset into train and test sets, define the model, train the model, and make predictions.

```
import numpy as np
import pandas as pd
from sklearn.model_selection import train_test_split
from sklearn.linear_model import LinearRegression
from sklearn.metrics import mean_squared_error
```

## Loading the Dataset

Next, we need to load the dataset. In this example, we will use a dataset containing information about the prices of houses in Boston. We will load the dataset using pandas and store it in a dataframe.

```
df = pd.read_csv('https://raw.githubusercontent.com/selva86/datasets/master/BostonHousing.csv')
```

## Splitting the Dataset into Train and Test sets

We need to split the dataset into train and test sets to evaluate the performance of the model. We will use the scikit-learn library to split the dataset into train and test sets. We will use 80% of the data for training the model and 20% of the data for testing the model.

```
X_train, X_test, y_train, y_test = train_test_split(df.drop('medv', axis=1), df['medv'], test_size=0.2, random_state=42)
```

## Defining the Model

We will use a simple linear regression model to predict the prices of houses. We will use the scikit-learn library to define the model.

```
model = LinearRegression()
```

## Training the Model

We will train the model using the training data.

```
model.fit(X_train, y_train)
```

## Making Predictions

We will use the trained model to make predictions on the test data.

```
y_pred = model.predict(X_test)
```

## Calculating MSE

We can use the mean_squared_error function from scikit-learn to calculate the MSE.

```
mse = mean_squared_error(y_test, y_pred)
print('MSE:', mse)
```

## Visualizing the Results

We can visualize the predictions and actual values using a scatter plot.

```
import matplotlib.pyplot as plt
plt.scatter(y_test, y_pred)
plt.xlabel('Actual')
plt.ylabel('Predicted')
plt.title('Actual vs. Predicted')
plt.show()
```

## Conclusion

In this article, we have explored how to calculate MSE in Python with writing patterns. We have gone through the basic concept of MSE, its importance, and how to implement it in Python programming language. We have also used a writing pattern to organize the code and make it more readable. By following this pattern, we can ensure that the code is consistent and easy to understand.