Terminology
Label
A label is the thing we're predicting—the variable in simple linear regression.
- ex. The label could be the future price of wheat, the kind of animal shown in a picture, the meaning of an audio clip, or just about anything.
Feature
A feature is an input variable—the x variable in simple linear regression. A simple machine learning project might use a single feature, while a more sophisticated machine learning project could use millions of features, specified as:
- ex. In a spam detector, the features could include: words in the email text, sender's address, time of day the email was sent, email contains the phrase "one weird trick."
Example
An example is a particular instance of (note: is a vector)
- each example is often represented by a vector of features.
Examples can be either unlabeled or labeled.
- A labeled example includes both feature(s) and the label
- An unlabeled example contains features but not the label.
Model
A model defines the relationship between features and label.
- ex. a spam detection model might associate certain features strongly with "spam".
There are 2 principle phases of a model's life:
- Training, which means creating or learning the model. That is, you show the model labeled examples and enable the model to gradually learn the relationships between features and label.
- Inference, which means applying the trained model to unlabeled examples. That is, you use the trained model to make useful predictions (
y'
).- ex. during inference, you can predict
medianHouseValue
for new unlabeled examples.
- ex. during inference, you can predict
Parameter
A model parameter is a configuration variable that is internal to the model and whose value can be estimated from data.
- that is, a parameter is a value that the model sets itself
In the context of neural networks, parameters
usually refer to weights
and biases
of the network.
Hyperparameter
A hyperparameter is a value that we (as a developer) set.
- ex.
learning rate
Epoch
Each time a dataset passes through an algorithm, it is said to have completed an epoch
- therefore, one epoch is one entire passing of training data through the algorithm
An epoch is a hyperparameter that determines the process of training the machine learning model
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