persistence

How to save to disk / export a lightgbm LGBMRegressor model trained in python?

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Try: my_model.booster_.save_model(‘mode.txt’) #load from model: bst = lgb.Booster(model_file=”mode.txt”) Note: the API state that bst = lgb.train(…) bst.save_model(‘model.txt’, num_iteration=bst.best_iteration) Depending on the version, one of the above works. For generic, You can also use pickle or something similar to freeze your model. import joblib # save model joblib.dump(my_model, ‘lgb.pkl’) # load model gbm_pickle = joblib.load(‘lgb.pkl’) Let … Read more

Why put a DAO layer over a persistence layer (like JDO or Hibernate)

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You make some points. But I nevertheless use a Dao layer, here’s why: Database accesses are calls to a remote system. In all such cases (also web-service, ajax etc…), the granularity of interaction need to be big enough. Many tiny calls would kill performance. This performance necessity requires often a different view of the system, … Read more

How can I write structured data to a file and then read it back into the same structure later?

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Why not use python pickle? Python has a great serializing module called pickle it is very easy to use. import cPickle cPickle.dump(obj, open(‘save.p’, ‘wb’)) obj = cPickle.load(open(‘save.p’, ‘rb’)) There are two disadvantages with pickle: It’s not secure against erroneous or maliciously constructed data. Never unpickle data received from an untrusted or unauthenticated source. The format … Read more

JPA Map mapping

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Although answer given by Subhendu Mahanta is correct. But @CollectionOfElements is deprecated. You can use @ElementCollection instead: @ElementCollection @JoinTable(name=”ATTRIBUTE_VALUE_RANGE”, joinColumns=@JoinColumn(name=”ID”)) @MapKeyColumn (name=”RANGE_ID”) @Column(name=”VALUE”) private Map<String, String> attributeValueRange = new HashMap<String, String>(); There is no need to create a separate Entity class for the Map field. It will be done automatically.

Will multiple calls to `now()` in a single PostgreSQL query always give the same result?

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The documentation says about now(): now() is a traditional PostgreSQL equivalent to transaction_timestamp() And about transaction_timestamp(): These SQL-standard functions all return values based on the start time of the current transaction So within one SQL statement, now() will always return the same value.

How can I tell if another instance of my program is already running?

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As Jon first suggested, you can try creating a mutex. Call CreateMutex. If you get a non-null handle back, then call GetLastError. It will tell you whether you were the one who created the mutex or whether the mutex was already open before (Error_Already_Exists). Note that it is not necessary to acquire ownership of the … Read more

In javascript, how can I uniquely identify one browser window from another which are under the same cookiedbased sessionId

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you could set your own window name, the exact syntax escapes me right now, but you can use the current time and session id to create a unique id on window load, then use that id This would be done the same way you set a name in the javascript window.open() function, (but you can … Read more

Which provider should be used for the Java Persistence API (JPA) implemenation [closed]

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When the Java Persistence API (API) was developed, it became popular very fast. JPA describes the management of relational data in applications using Java. JPA (Java Persistence API) is an interface for persistence providers to implement. Hibernate is one such implementation of JPA. When you use Hibernate with JPA you are actually using the Hibernate … Read more

@JoinFormula and @OneToMany definition – poor documentation

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Answer 1 : @Size(max=10) private List<Comment> commentList; Answer 2 :(just example like that) public class A{ @Id @GeneratedValue private Integer id; private String uuid; … } other class public class B{ @Id @GeneratedValue private Integer id; private String uuidOfA; @ManyToOne @JoinColumnsOrFormulas({ @JoinColumnOrFormula(formula=@JoinFormula(value=”(SELECT a.id FROM A a WHERE a.uuid = uuid)”, referencedColumnName=”id”)), @JoinColumnOrFormula(column = @JoinColumn(“uuidOfA”, referencedColumnName=”uuid”)) … Read more

Hata!: SQLSTATE[HY000] [1045] Access denied for user 'divattrend_liink'@'localhost' (using password: YES)