GitLab

Created by: MorrisNein

These changes elaborate the PR #700.

1. Python objects change list:

• Individual and ParentOperator classes are now frozen data classes;
• Every uid now normally exists in a single Individual object. This is a soft restriction, though, and any violation will be noticed with warning;
• fitness and graph of Individual now can be updated only once - during its evaluation;
• Individual has a new attribute called native_generation. It points to the number of generation in which the individual is obtained;
• parent_operators of individuals are not cleaned in every generation any more;
• Individual.parent_operators and ParentOperator.parent_individuals are now tuples;
• Side change: Moved SingletonMeta from fedot.core.log to fedot.core.utilities.singleton_meta
• Bug fix: OptNode now accepts content with params, not replacing parameters with default stub.
• Minor: ind argument of mutate() now has explicit name individual;
• Minor: many typing fixes.

2. OptHitsory serialization change list:

• Serialized OptHistory now has an attribute called individuals_pool. It contains all unique individuals from the history;
• In history JSON, individuals and archive_history now contain only uids that point to the elements of individuals_pool;
• Any intermediate parent, that is not represented in any generation, is placed to individuals_pool. Its children point to it via its uid;
• As a bonus, newly-saved history JSONs now take much less size (about 10+ times lesser);
• All individuals not found in loaded histories now are re-created with the same uid. Their metadata contains an explicit message explaining that they are missing;
• Added support for relatively recent histories;
• Improved OptHistory tests to guarantee stability and backward compatibility;
• Updated the histories stored in Git repo.