A Python dictionary is a collection of key-value pairs used to store data in an unordered, mutable structure. You create a dictionary using curly braces `{}` with key-value pairs, for example: `my_dict = {"name": "Alice", "age": 25}`. You can also use the `dict()` constructor to create dictionaries. Accessing values is done by referring to their keys: `my_dict["name"]` returns `"Alice"`.
You add or update items by assigning a value to a key, such as `my_dict["city"] = "New York"` to add new or
🐍 Python Loop and Branching Statements
Python provides powerful structures for iteration (loops) and flow control (branching statements) that allow you to execute blocks of code repeatedly or conditionally.
Python Loop Statements
Loops are used to execute a block of code multiple times. The main loop types in Python are while and for.
1. The while Loop
The while loop repeatedly executes a block of statements as long as a given condition is True.
* Syntax:
while condition:
# statement(s)
Keywords and identifiers are fundamental elements in programming languages used to define variables, functions, and other constructs, with keywords being reserved words that have special meanings, and identifiers being names given to user-defined entities.
Comments in programming serve the essential purpose of making the source code more understandable and maintainable by providing textual annotations that explain the logic, purpose, or any additional information about the code. They help programmers
## Hybrid Hash-Join — Step-by-Step Conceptual Explanation (Exam-Friendly)
Hybrid Hash-Join is an **improved version of Hash-Join** that reduces disk I/O by using memory more efficiently during the join operation.
It is particularly useful when:
* The **build relation is larger than memory**
* But memory is **still large enough** to hold **one or more partitions** fully
## Why Hybrid Hash-Join?
In a normal Hash-Join:
* All partitions of build relation are written to disk first
* Then read again for...
Cuando un cliente llega al hotel, el recepcionista debe comprobar su reserva o la disponibilidad de habitaciones (si no ha reservado), preguntando los datos necesarios (fecha de salida, tipo de habitación y servicios solicitados).
Antes de asignarle una habitación, se debe pedir un documento. Los viajeros españoles suelen entregar el DNI (Documento Nacional de Identidad), pero se pueden aceptar también el pasaporte o el carné de conducir. Además, cada establecimiento turístico tiene la obligación
Two objects are indiscernible if they have same values for a chosen set of attributes.
Forms equivalence classes (granules).
Basis for lower/upper approximations in Rough Sets.
Reduct
Minimum subset of attributes giving same classification power as full set.
Removing any attribute → information loss.
Core
Intersection of all reducts.
Contains attributes must for classification.
Example (Medical dataset)
Attributes: