Topic -- Principle Component Analysis
(PCA) Part 1
PCA statistics is science of analyzing all the dimension & reducing them as much as possible while preserving exact information
You can monitor multi-dimensional data (can visualize in 2D or 3D dimension) over any platform using the Principal Component Method of factor analysis.
Step by step explanation of Principal Component Analysis
STANDARDIZATION
COVARIANCE MATRIX COMPUTATION
FEATURE VECTOR
RECAST THE DATA ALONG THE PRINCIPAL COMPONENTS AXES
Applications of PCA Analysis
- PCA in machine learning is used to visualize multidimensional data.
- In healthcare data to explore the factors that are assumed to be very important in increasing the risk of any chronic disease.
- PCA helps to resize an image.
Disadvantages of PCA
Sometimes, PCA is difficult to interpret. In rare cases, you may feel difficult to identify the most important features even after computing the principal components.
You may face some difficulties in calculating the covariances and covariance matrices.
Refers to phenomenon where the performance of ML algorithms deteriorates as No. of dimension or feature of input data ⬆️
This is because the volume of space increases exponentially with No. of dimension which causes data to become sparse & distance btwn data point to increase
Many ML algorithms struggle to find meaningful patterns & relationships in high-dimensional data & may suffer from overfitting or poor generalization performance. This can lead to longer training time increased memory requirements & reduced accuracy & efficiency in predictions.
Feature construction is a critical aspect of feature engineering, which involves the process of creating new features or transforming existing ones to improve the performance of machine learning models.
The goal of feature construction is to extract meaningful information from raw data and represent it in a way that can be effectively used by machine learning algorithms.
🎯Are NULL values same as that of zero or a blank space❓
🔺A NULL value is not at all same as that of zero or a blank space.
🔺NULL value represents a value which is unavailable, unknown, assigned or not applicable whereas a zero is a number and blank space is a character.
🎯What is the usage of the NVL() function❓
🔹Answer
🔺You may use NVL function to replace null values with a default value. 🔺The function returns the value of second parameter if first parameter is null.
🔺If the first parameter is anything other than null, it is left alone