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Data pre-processing is the process of transforming raw data into something that a machine learning model can use. It is the initial and most important step in developing a machine learning model.
We rarely have access to clean, well-formatted data while developing a machine learning project. Moreover, data must always be cleaned and formatted before being used in any activity. A data preparation task is used in this case.
What is the purpose of data pre-processing?
Real-world data often contains noise, missing values, and undesirable formats, which hinder direct machine learning model building. ML teams aim for optimal model performance on test data, but achieving it is rare.
There could be various causes. However, the main offenders include:
- Lack of sufficient data
- Poor quality data
- Bad choice of algorithm
- Hyperparameter tuning
- Bias in the dataset
It’s also vital to note that pre-processing approaches are crucial for increasing the model’s interpretability and robustness, and performance. To avoid overfitting and provide models that generalize more effectively to new data, for instance, handle missing values, eliminate outliers, and scale the data.
This process aids in ensuring that the data is clean, error-free, and in a format that the algorithm can understand to avoid any potential effects on the model’s performance.
Pre-processing data reduces training time and resources. Removing unnecessary or redundant data significantly reduces the amount of data for the algorithm to process, leading to more efficient model training.
The interpretability of the model can also be enhanced by pre-processing the data. Comprehending the relationships among different variables and how they affect the model’s predictions will be simpler if the data is cleaned and formatted.
This can assist us in better understanding the behavior of the model and in deciding how to enhance it.
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Steps to follow to ensure your Data Pre-Processing
- Data quality assessment:
Nearly every data set has a variety of data abnormalities and underlying issues that should be looked out for, such as:
- Inconsistent data types: Data from diverse sources often comes in different formats. The ultimate goal is to prepare the data for machines. For instance, when dealing with family income from multiple countries, converting each number into a unified currency is essential.
- Mixed data values: It is possible that several sources used various descriptors for traits, such as man or male. All of these value descriptions ought to be uniform.
- Data outliers: Outliers can significantly affect the outcomes of data analysis. For instance, one student’s 0% could significantly skew the statistics if you averaged the test scores for the entire class.
- Missing Data: Look for empty text boxes, missing data fields, or unresolved survey questions. This could occur as a result of incomplete or faulty data. You must undertake data cleaning to address any missing data.
- Data Cleaning:
Data set completion requires adding missing data and fixing or removing inaccurate or unnecessary data. The essential step in pre-processing is data cleaning, ensuring data readiness for subsequent use.
Data cleaning resolves inconsistencies identified during data quality review. Various cleansing techniques are applied based on the data type.
- Data transformation:
The data conversion procedure into the appropriate format(s) required for analysis and other downstream operations will start with data transformation.
This typically occurs in at least one of the following:
- Aggregation: Your data are all combined in a standard way using data aggregation.
- Normalization: To improve comparison accuracy, your data is scaled into a regularised range during normalization. For instance, you must scale the Daily Stock Price Loss or Gain of a Company within a predetermined range, such as -1.0 to 1.0 or 0.0 to 1.0.
- Feature Selection: Feature selection is crucial in studies and involves choosing essential features. These features are used to train machine learning models. However, selecting more features prolongs training and may decrease accuracy due to overlapping or less prevalent characteristics.
- Data Reduction:
Cleaning and processing data doesn’t guarantee easy interpretation with larger datasets. You may have excessive data for your task. Most human speech is unnecessary for research, particularly in text analysis. Data reduction simplifies the analysis by decreasing stored data.
- Attribute selection: Your data may fit into smaller pools if you choose certain attributes. In essence, it merges tags or features, allowing tags like male/female and professor to be combined into male professor/female professor.
- Numerosity reduction: Data transmission and storage will benefit from this. For instance, you can use a regression model to use only the information and variables important to your study.
- Dimensionality reduction: This reduces the data needed to support analysis and subsequent procedures. Algorithms like K-nearest neighbors use pattern recognition to group similar data and make it easier to handle.
Data Pre-processing services in AWS
AWS offers several services for pre-processing data that might assist you in getting your data ready for analysis, modeling, and other subsequent procedures. Among the most well-liked services are the following:
- AWS Glue: You can prepare and transform your data for analytics with AWS Glue, a fully managed extract, transform, and load (ETL) service. You can build data pipelines using AWS Glue that transmit data across different data stores, transform and clean the data, and even automatically predict and produce ETL code.
- Amazon EMR: You can use distributed computing to process significant amounts of data using the managed Hadoop and Spark platform, Amazon EMR. You can quickly build Hadoop and Spark clusters with EMR that can process huge amounts of data in parallel, enabling you to finish your data processing jobs more quickly.
These are only a few of the data pre-processing services that AWS offers. Depending on your use case, you might also want to consider additional AWS services like AWS Data Pipeline, Amazon Kinesis, and Amazon Redshift.
Pre-processing Data before using it with a machine learning algorithm is essential in the ML workflow. It aids in enhancing the model’s interpretability, preventing overfitting, reducing the time and resources needed to train the model, and improving accuracy.
Drop a query if you have any questions regarding Data pre-Processing and we will get back to you quickly.
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1. What is data cleaning in machine learning?
ANS: – By locating and eliminating errors, duplicates, and unneeded data, data cleaning in machine learning produces data that is accurate, correct, and relevant. The model may suffer from erroneous data with missing or negative values.
2. What is the main goal of data analysis?
ANS: – The main goal of data analysis is to find significant insights from the data to make educated and precise judgments.
3. What are the steps of Data Pre-processing?
ANS: – Data quality assessment, Data cleaning, Data transformation, Data reduction.
WRITTEN BY Aritra Das
Aritra Das works as a Research Associate at CloudThat. He is highly skilled in the backend and has good practical knowledge of various skills like Python, Java, Azure Services, and AWS Services. Aritra is trying to improve his technical skills and his passion for learning more about his existing skills and is also passionate about AI and Machine Learning. Aritra is very interested in sharing his knowledge with others to improve their skills.