relationship

Cosine similarity vs Hamming distance [closed]

由 一个人想着一个人 提交于 2019-11-27 04:13:37
问题 Closed . This question is opinion-based. It is not currently accepting answers. Want to improve this question? Update the question so it can be answered with facts and citations by editing this post. Closed 4 years ago . To compute the similarity between two documents, I create a feature vector containing the term frequencies. But then, for the next step, I can't decide between "Cosine similarity" and "Hamming distance". My question: Do you have experience with these algorithms? Which one

SQLAlchemy: How to order query results (order_by) on a relationship's field?

由 谁说胖子不能爱 提交于 2019-11-27 02:33:59
问题 Models from sqlalchemy.ext.declarative import declarative_base from sqlalchemy import Column, ForeignKey from sqlalchemy import Integer from sqlalchemy import Unicode from sqlalchemy import TIMESTAMP from sqlalchemy.orm import relationship BaseModel = declarative_base() class Base(BaseModel): __tablename__ = 'base' id = Column(Integer, primary_key=True) location = Column(Unicode(12), ForeignKey("locationterrain.location"), unique=True,) name = Column(Unicode(45)) ownerid = Column(Integer

many-to-many relationship in database design

由 谁说我不能喝 提交于 2019-11-27 02:24:47
问题 I currently have a database with two tables called Articles and Tags . In order to allow articles to be in multiple categories i have a many to many relationship. Is it a mistake to have such a design in terms of performance? or should i remove the relationship between these two table and add a third table as a bridge (articlesTags)? 回答1: There's nothing inherently wrong with having a many-to-many relationship, you'll just need to create a Junction Table (which is what it sounds like you're

Saving CoreData to-many relationships in Swift

由 南楼画角 提交于 2019-11-26 22:42:14
问题 I have a one-to-many relationship that looks like so, I've set up my model classes in a file to match: import CoreData import Foundation class Board: NSManagedObject { @NSManaged var boardColor: String @NSManaged var boardCustomBackground: AnyObject? @NSManaged var boardID: String @NSManaged var boardName: String @NSManaged var lists: NSSet } class List: NSManagedObject { @NSManaged var listID: String @NSManaged var listName: String @NSManaged var board: Board } Because I'm fetching data from

UML association vs. composition and detail level

由 北城以北 提交于 2019-11-26 19:25:08
问题 Actually, make that a couple of amateur UML questions! When creating a UML diagram to model some domain concepts and you come across a domain concept that "holds" some information about another concept, is it better to hold a stamp/reference to that entity or hold the whole entity in the model itself? Please bear in mind that this is relating to creating a simple high-level model - I'm sure in the implementation stage things would be slightly different. For example, which of the two models

What Kind of Relationship is Between These Tables?

由 送分小仙女□ 提交于 2019-11-26 17:51:56
问题 I have two tables that have foreign keys to each other's primary key. This DB is in French. I will translate the two tables that I want to you to understand. Atelier Cuisine ==> Kitchen Cuisinier == > Cooking chef So in this picture we see that in the Kitchen table we have a PK referenced by the FK from the Cooking chef table; in the Cooking chef table we have a PK referenced by the FK from the Kitchen table. So I am confused. I don't understand this kind of relationship between these tables.

How to find all the relations between all mysql tables?

由 你离开我真会死。 提交于 2019-11-26 15:41:30
问题 How to find all the relations between all MySQL tables? If for example, I want to know the relation of tables in a database of having around 100 tables. Is there anyway to know this? 回答1: The better way, programmatically speaking, is gathering data from INFORMATION_SCHEMA.KEY_COLUMN_USAGE table as follows: SELECT `TABLE_SCHEMA`, -- Foreign key schema `TABLE_NAME`, -- Foreign key table `COLUMN_NAME`, -- Foreign key column `REFERENCED_TABLE_SCHEMA`, -- Origin key schema `REFERENCED_TABLE_NAME`,

Ruby on rails - Reference the same model twice?

由 余生长醉 提交于 2019-11-26 15:09:33
问题 Is it possible to set up a double relationship in activerecord models via the generate scaffold command? For example, if I had a User model and a PrivateMessage model, the private_messages table would need to keep track of both the sender and recipient . Obviously, for a single relationship I would just do this: ruby script/generate scaffold pm title:string content:string user:references Is there a similar way to set up two relations? Also, is there anyway to set up aliases for the relations?

Laravel - Eloquent “Has”, “With”, “WhereHas” - What do they mean?

由 为君一笑 提交于 2019-11-26 14:49:08
I've found the concept and meaning behind these methods to be a little confusing, is it possible for somebody to explain to me what the difference between has and with is, in the context of an example (if possible)? lukasgeiter With with() is for eager loading . That basically means, along the main model, Laravel will preload the relationship(s) you specify. This is especially helpful if you have a collection of models and you want to load a relation for all of them. Because with eager loading you run only one additional DB query instead of one for every model in the collection. Example: User

Filtering relationships in SQL Alchemy

由 泄露秘密 提交于 2019-11-26 14:47:03
问题 I have the following scenario: class Author(Base): __tablename__ = 'author' id = Column(Integer, primary_key = True) name = Column(String) books = relationship('Books', backref='author') class Book(Base): __tablename__ = 'book' id = Column(Integer, primary_key = True) title = Column(String) What I would like to do is load all authors who have a book containing SQL in the title. i.e. authors = session.query(Author)\ .join(Author.books)\ .filter(Book.title.like('%SQL%')\ .all() Seems simple.
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