What is Data transformation? Easy Definition, Types, and 11+ Examples
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Definition:
Data transformation involves converting data from one format, structure, or representation into another, often to make it more suitable for analysis, visualization, or processing. It's a critical step in data preparation that helps enhance the quality and usability of the data.
Data transformation Types:
1. Structural Transformation: Changing the structure or format of the data. Examples include converting data from wide to long format or vice versa, reshaping data for machine learning algorithms, or restructuring relational databases.
2. Value Transformation: Modifying the actual values or content of the data. This can involve cleaning data by removing inconsistencies or errors, normalizing data to a standard scale, converting data types (e.g., from string to numeric), or encoding categorical variables into numerical representations.
3. Feature Transformation: Creating new features or variables from existing ones to improve predictive modeling or analysis. This includes feature engineering, where new features are derived from existing ones, and dimensionality reduction techniques like PCA (Principal Component Analysis) or t-SNE (t-distributed Stochastic Neighbor Embedding).
Data transformation Examples:
1. Type Conversion: Changing data types, such as converting strings to integers or dates to a standardized format.
Example: Converting "2023-05-15" (string) to a date format (e.g., YYYY-MM-DD).
2. Scaling/Normalization: Rescaling numeric data to a common scale to prevent certain variables from dominating others in analysis. This is crucial for algorithms like K-Means clustering or Neural Networks.
Example: Scaling a dataset where one feature ranges from 0 to 100 and another from 0 to 100,000 to a common scale like 0 to 1.
3. Aggregation: Combining multiple data points into summary statistics or aggregating data over different time periods or categories.
Example: Calculating the total sales revenue per month from daily sales data.
4. Encoding: Converting categorical variables into numerical representations that can be used in statistical models or machine learning algorithms.
Example: Representing "red," "blue," and "green" as 1, 2, and 3 respectively.
5. Feature Engineering: Creating new features from existing ones to capture more information or improve model performance.
Example: Generating a "total orders per customer" feature from an e-commerce dataset containing individual order records.
6. Text Preprocessing: Cleaning and preprocessing text data to remove noise, standardize formats, and prepare it for natural language processing tasks.
Example: Tokenizing sentences into individual words, removing punctuation and stopwords, and converting all text to lowercase.
7. Temporal Transformation: Converting temporal data into different formats or aggregating it into different time intervals.
Example: Converting timestamps to different time zones or aggregating daily sales data into weekly or monthly totals.
8. Imputation: Filling in missing values in a dataset using statistical methods, such as mean, median, or mode imputation, or more advanced techniques like k-nearest neighbors (KNN) imputation or predictive modeling.
Example: Filling missing age values in a dataset using the mean age of the population.
9. Outlier Detection and Handling: Identifying and transforming or removing outliers in the data to improve model performance and robustness.
Example: Replacing outliers in a dataset with the nearest non-outlier values or removing them entirely.
10. Feature Scaling: Scaling numerical features to a similar range to prevent certain features from dominating others in algorithms that rely on distance measures or gradients.
Example: Scaling features such as income, age, and expenditure to have a mean of 0 and a standard deviation of 1.
11. One-Hot Encoding: Encoding categorical variables into binary vectors with a separate binary variable for each category.
Example: Encoding categorical variables like "gender" with values "male" and "female" into binary variables (e.g., [1, 0] for male and [0, 1] for female).
12. Data Augmentation: Generating additional training examples by applying random transformations to existing data, commonly used in computer vision and natural language processing tasks.
Example: Creating new images for a dataset by flipping, rotating, or adding noise to existing images.
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