https://github.com/waikato-datamining/opex4j

Java library for the OPEX JSON format.
https://github.com/waikato-datamining/opex4j

java json object-detection

Last synced: about 2 months ago
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Java library for the OPEX JSON format.

• Host: GitHub
• URL: https://github.com/waikato-datamining/opex4j
• Owner: waikato-datamining
• License: mit
• Created: 2023-02-27T19:51:19.000Z (almost 2 years ago)
• Default Branch: main
• Last Pushed: 2024-06-18T22:32:44.000Z (6 months ago)
• Last Synced: 2024-06-20T03:40:56.286Z (6 months ago)
• Topics: java, json, object-detection
• Language: Java
• Homepage:
• Size: 29.3 KB
• Stars: 0
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# opex4j

Java library for the [OPEX JSON format](https://github.com/WaikatoLink2020/objdet-predictions-exchange-format)

(faster Python alternative: [fast-opex](https://github.com/waikato-datamining/fast-opex)).

## JSON

Here is an [example](src/test/resources/opex4j/simple.json):

```json

{

  "timestamp": "...",

  "id": "str",

  "objects": [

    {

      "score": 1.0,

      "label": "person",

      "bbox": {

        "top": 100,

        "left": 100,

        "bottom": 150,

        "right": 120

      },

      "polygon": {

        "points": [

          [100, 100],

          [150, 100],

          [150, 120],

          [100, 120]

        ]

      }

    },

    {

      "score": 0.95,

      "label": "house",

      "bbox": {

        "top": 100,

        "left": 100,

        "bottom": 200,

        "right": 200

      },

      "polygon": {

        "points": [

          [100, 100],

          [200, 100],

          [200, 200],

          [100, 200]

        ]

      },

      "meta": {

        "price": "500k"

      }

    }

  ],

  "meta": {

    "key1": "value1",

    "key2": "value2"

  }

}

```

**Notes:**

* supported timestamp formats: `yyyyMMdd_HHmmss.SSSSSS` and `yyyy-MM-dd HH:mm:ss.SSSSSS`

## Reading/Writing

To read predictions:

```java

import opex4j.ObjectPredictions;

import java.io.InputStream;

import java.io.File;

import java.io.Reader;

public class Examples {

  public static void main(String[] args) throws Exception {

    // from string

    ObjectPredictions preds = ObjectPredictions.newInstance("{...}");

    // from file

    ObjectPredictions preds = ObjectPredictions.newInstance(new File("predictions.json"));

    // from reader

    Reader reader = ...;

    ObjectPredictions preds = ObjectPredictions.newInstance(reader);

    reader.close();

 

    // from stream

    InputStream stream = ...;

    ObjectPredictions preds = ObjectPredictions.newInstance(stream);

    stream.close();

  }

}

```

To write predictions:

```java

import opex4j.ObjectPredictions;

import java.io.File;

import java.io.OutputStream;

import java.io.Writer;

public class Examples {

  public static void main(String[] args) throws Exception {

    ObjectPredictions preds = ...;

    // to string (not pretty printed)

    String s = preds.toString(false);

    // to file (pretty printed, implicitly)

    ObjectPredictions.write(new File("predictions.json"));

    // to writer (pretty printed, explicitly)

    Writer writer = ...;

    ObjectPredictions.write(writer, true);

    writer.close();

 

    // to stream (not pretty printed)

    OutputStream stream = ...;

    preds.write(stream, false);

    stream.close();

  }

}

```

## Maven

Use the following dependency in your `pom.xml`:

```xml

    

      nz.ac.waikato.cms.adams

      opex4j

      0.0.3

    

```