harmony 鸿蒙@ohos.ai.mindSporeLite (Inference)

  • 2023-10-30
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@ohos.ai.mindSporeLite (Inference)

MindSpore Lite is an AI engine that implements AI model inference for different hardware devices. It has been used in a wide range of fields, such as image classification, target recognition, facial recognition, and character recognition. The mindSporeLite module provides APIs for the MindSpore Lite inference engine to implement model inference.

NOTE

The initial APIs of this module are supported since API version 10. Newly added APIs will be marked with a superscript to indicate their earliest API version. Unless otherwise stated, the MindSpore model is used in the sample code.

The APIs of this module can be used only in the stage model.

Modules to Import

import mindSporeLite from '@ohos.ai.mindSporeLite';

Context

Defines the configuration information of the running environment.

Attributes

System capability: SystemCapability.AI.MindSporeLite

Name Type Readable Writable Description
target string[] Yes Yes Target backend. The value can be cpu or nnrt. The default value is cpu.
cpu CpuDevice Yes Yes CPU backend device option. Set this parameter set only when target is set to cpu. The default value is the combination of the default value of each CpuDevice option.
nnrt NNRTDevice Yes Yes NNRt backend device option. Set this parameter set only when target is set to nnrt. Currently, this parameter is empty.

Example

let context: mindSporeLite.Context = {};
context.target = ['cpu','nnrt'];

CpuDevice

Defines the CPU backend device option.

Attributes

System capability: SystemCapability.AI.MindSporeLite

Name Type Readable Writable Description
threadNum number Yes Yes Number of runtime threads. The default value is 2.
threadAffinityMode ThreadAffinityMode Yes Yes Affinity mode for binding runtime threads to CPU cores. The default value is mindSporeLite.ThreadAffinityMode.NO_AFFINITIES.
threadAffinityCoreList number[] Yes Yes List of CPU cores bound to runtime threads. Set this parameter only when threadAffinityMode is set. If threadAffinityMode is set to mindSporeLite.ThreadAffinityMode.NO_AFFINITIES, this parameter is empty. The number in the list indicates the SN of the CPU core. The default value is [].
precisionMode string Yes Yes Whether to enable the Float16 inference mode. The value preferred_fp16 means to enable half-precision inference and the default value enforce_fp32 means to disable half-precision inference. Other settings are not supported.

Float16 inference mode: a mode that uses half-precision inference. Float16 uses 16 bits to represent a number and therefore it is also called half-precision.

Example

let context: mindSporeLite.Context = {};
context.cpu = {};
context.target = ['cpu'];
context.cpu.threadAffinityMode = 0;
context.cpu.precisionMode = 'preferred_fp16';
context.cpu.threadAffinityCoreList = [0, 1, 2];

NNRTDevice

Represents an NNRt device. Neural Network Runtime (NNRt) is a bridge that connects the upper-layer AI inference framework to the bottom-layer acceleration chip to implement cross-chip inference and computing of AI models. An NNRt backend can be configured for MindSpore Lite. Currently, this API is not supported.

System capability: SystemCapability.AI.MindSporeLite

ThreadAffinityMode

Specifies the affinity mode for binding runtime threads to CPU cores.

System capability: SystemCapability.AI.MindSporeLite

Name Value Description
NO_AFFINITIES 0 No affinities.
BIG_CORES_FIRST 1 Big cores first.
LITTLE_CORES_FIRST 2 Medium cores first.

mindSporeLite.loadModelFromFile

loadModelFromFile(model: string, callback: Callback<Model>): void

Loads the input model from the full path for model inference. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model string Yes Complete path of the input model.
callback Callback<Model> Yes Callback used to return the result, which is a Model object.

Example

let model_file : string = '/path/to/xxx.ms';
mindSporeLite.loadModelFromFile(model_file, (result : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
  console.log(modelInputs[0].name);
})

mindSporeLite.loadModelFromFile

loadModelFromFile(model: string, context: Context, callback: Callback&lt;Model&gt;): void

Loads the input model from the full path for model inference. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model string Yes Complete path of the input model.
context Context Yes Configuration information of the running environment.
callback Callback<Model> Yes Callback used to return the result, which is a Model object.

Example

let context: mindSporeLite.Context = {};
context.target = ['cpu'];
let model_file : string = '/path/to/xxx.ms';
mindSporeLite.loadModelFromFile(model_file, context, (result : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
  console.log(modelInputs[0].name);
})

mindSporeLite.loadModelFromFile

loadModelFromFile(model: string, context?: Context): Promise&lt;Model&gt;

Loads the input model from the full path for model inference. This API uses a promise to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model string Yes Complete path of the input model.
context Context No Configuration information of the running environment.

Return value

Type Description
Promise<Model> Promise used to return the result, which is a Model object.

Example

let model_file = '/path/to/xxx.ms';
mindSporeLite.loadModelFromFile(model_file).then((result : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
  console.log(modelInputs[0].name);
})

mindSporeLite.loadModelFromBuffer

loadModelFromBuffer(model: ArrayBuffer, callback: Callback&lt;Model&gt;): void

Loads the input model from the memory for inference. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model ArrayBuffer Yes Memory that contains the input model.
callback Callback<Model> Yes Callback used to return the result, which is a Model object.

Example

// Construct a singleton object.
export class GlobalContext {
  private constructor() {}
  private static instance: GlobalContext;
  private _objects = new Map<string, Object>();

  public static getContext(): GlobalContext {
    if (!GlobalContext.instance) {
      GlobalContext.instance = new GlobalContext();
    }
    return GlobalContext.instance;
  }

  getObject(value: string): Object|undefined {
    return this._objects.get(value);
  }

  setObject(key: string, objectClass: Object): void {
    this._objects.set(key, objectClass);
  }

}
import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
export class Test {
  value:number = 0;
  foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
  }
}
let globalContext = GlobalContext.getContext().getObject("value") as common.UIAbilityContext;

let modelName = '/path/to/xxx.ms';
globalContext.resourceManager.getRawFileContent(modelName).then((buffer : Uint8Array) => {
  let modelBuffer : ArrayBuffer = buffer.buffer;
  mindSporeLite.loadModelFromBuffer(modelBuffer, (result : mindSporeLite.Model) => {
    let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
    console.log(modelInputs[0].name);
  })
})

mindSporeLite.loadModelFromBuffer

loadModelFromBuffer(model: ArrayBuffer, context: Context, callback: Callback&lt;Model&gt;): void

Loads the input model from the memory for inference. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model ArrayBuffer Yes Memory that contains the input model.
context Context Yes Configuration information of the running environment.
callback Callback<Model> Yes Callback used to return the result, which is a Model object.

Example

import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
let modelName = '/path/to/xxx.ms';
export class Test {
  value:number = 0;
  foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
  }
}
let globalContext= GlobalContext.getContext().getObject("value") as common.UIAbilityContext;

globalContext.resourceManager.getRawFileContent(modelName).then((buffer : Uint8Array) => {
  let modelBuffer : ArrayBuffer = buffer.buffer;
  let context: mindSporeLite.Context = {};
  context.target = ['cpu'];
  mindSporeLite.loadModelFromBuffer(modelBuffer, context, (result : mindSporeLite.Model) => {
    let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
    console.log(modelInputs[0].name);
  })
})

mindSporeLite.loadModelFromBuffer

loadModelFromBuffer(model: ArrayBuffer, context?: Context): Promise&lt;Model&gt;

Loads the input model from the memory for inference. This API uses a promise to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model ArrayBuffer Yes Memory that contains the input model.
context Context No Configuration information of the running environment.

Return value

Type Description
Promise<Model> Promise used to return the result, which is a Model object.

Example

import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
let modelName = '/path/to/xxx.ms';
export class Test {
  value:number = 0;
  foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
  }
}
let globalContext = GlobalContext.getContext().getObject("value") as common.UIAbilityContext;

globalContext.resourceManager.getRawFileContent(modelName).then((buffer : Uint8Array) => {
  let modelBuffer : ArrayBuffer = buffer.buffer;
  mindSporeLite.loadModelFromBuffer(modelBuffer).then((result : mindSporeLite.Model) => {
    let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
    console.log(modelInputs[0].name);
  })
})

mindSporeLite.loadModelFromFd

loadModelFromFd(model: number, callback: Callback&lt;Model&gt;): void

Loads the input model based on the specified file descriptor for inference. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model number Yes File descriptor of the input model.
callback Callback<Model> Yes Callback used to return the result, which is a Model object.

Example

import fs from '@ohos.file.fs';
let model_file = '/path/to/xxx.ms';
let file = fs.openSync(model_file, fs.OpenMode.READ_ONLY);
mindSporeLite.loadModelFromFd(file.fd, (result : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
  console.log(modelInputs[0].name);
})

mindSporeLite.loadModelFromFd

loadModelFromFd(model: number, context: Context, callback: Callback&lt;Model&gt;): void

Loads the input model based on the specified file descriptor for inference. This API uses an asynchronous callback to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model number Yes File descriptor of the input model.
context Context Yes Configuration information of the running environment.
callback Callback<Model> Yes Callback used to return the result, which is a Model object.

Example

import fs from '@ohos.file.fs';
let model_file = '/path/to/xxx.ms';
let context : mindSporeLite.Context = {};
context.target = ['cpu'];
let file = fs.openSync(model_file, fs.OpenMode.READ_ONLY);
mindSporeLite.loadModelFromFd(file.fd, context, (result : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
  console.log(modelInputs[0].name);
})

mindSporeLite.loadModelFromFd

loadModelFromFd(model: number, context?: Context): Promise&lt; Model&gt;

Loads the input model based on the specified file descriptor for inference. This API uses a promise to return the result.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
model number Yes File descriptor of the input model.
context Context No Configuration information of the running environment.

Return value

Type Description
Promise<Model> Promise used to return the result, which is a Model object.

Example

import fs from '@ohos.file.fs';
let model_file = '/path/to/xxx.ms';
let file = fs.openSync(model_file, fs.OpenMode.READ_ONLY);
let mindSporeLiteModel : mindSporeLite.Model = await mindSporeLite.loadModelFromFd(file.fd);
let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();
console.log(modelInputs[0].name);

Model

Represents a Model instance, with properties and APIs defined.

In the following sample code, you first need to use loadModelFromFile(), loadModelFromBuffer(), or loadModelFromFd() to obtain a Model instance before calling related APIs.

getInputs

getInputs(): MSTensor[]

Obtains the model input for inference.

System capability: SystemCapability.AI.MindSporeLite

Return value

Type Description
MSTensor[] MSTensor object.

Example

let model_file = '/path/to/xxx.ms';
mindSporeLite.loadModelFromFile(model_file).then((result : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = result.getInputs();
  console.log(modelInputs[0].name);
})

predict

predict(inputs: MSTensor[], callback: Callback&lt;MSTensor[]&gt;): void

Executes the inference model. This API uses an asynchronous callback to return the result. Ensure that the model object is not reclaimed when being invoked.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
inputs MSTensor[] Yes List of input models.
callback Callback<MSTensor[]> Yes Callback used to return the result, which is a list of MSTensor objects.

Example

import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
export class Test {
  value:number = 0;
  foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
  }
}
let globalContext = GlobalContext.getContext().getObject("value") as common.UIAbilityContext;

let inputName = 'input_data.bin';
globalContext.resourceManager.getRawFileContent(inputName).then(async (buffer : Uint8Array) => {
  let modelBuffer : ArrayBuffer = buffer.buffer;
  let model_file : string = '/path/to/xxx.ms';
  let mindSporeLiteModel : mindSporeLite.Model = await mindSporeLite.loadModelFromFile(model_file);
  let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();

  modelInputs[0].setData(modelBuffer);
  mindSporeLiteModel.predict(modelInputs, (result : mindSporeLite.MSTensor[]) => {
    let output = new Float32Array(result[0].getData());
    for (let i = 0; i < output.length; i++) {
      console.log(output[i].toString());
    }
  })
})

predict

predict(inputs: MSTensor[]): Promise&lt;MSTensor[]&gt;

Executes the inference model. This API uses a promise to return the result. Ensure that the model object is not reclaimed when being invoked.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
inputs MSTensor[] Yes List of input models.

Return value

Type Description
MSTensor[] List of MSTensor objects.

Example

import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
export class Test {
    value:number = 0;
    foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
}
}
let globalContext = GlobalContext.getContext().getObject("value") as common.UIAbilityContext;;
let inputName = 'input_data.bin';
globalContext.resourceManager.getRawFileContent(inputName).then(async (buffer : Uint8Array) => {
  let inputBuffer = buffer.buffer;
  let model_file = '/path/to/xxx.ms';
  let mindSporeLiteModel : mindSporeLite.Model = await mindSporeLite.loadModelFromFile(model_file);
  let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();
  modelInputs[0].setData(modelBuffer);
  mindSporeLiteModel.predict(modelInputs).then((result : mindSporeLite.MSTensor[]) => {
    let output = new Float32Array(result[0].getData());
    for (let i = 0; i < output.length; i++) {
      console.log(output[i].toString());
    }
  })
})

resize

resize(inputs: MSTensor[], dims: Array&lt;Array&lt;number&gt;&gt;): boolean

Resets the tensor size.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
inputs MSTensor[] Yes List of input models.
dims Array&lt;Array&lt;number&gt;&gt; Yes Target tensor size.

Return value

Type Description
boolean Result indicating whether the setting is successful. The value true indicates that the tensor size is successfully reset, and the value false indicates the opposite.

Example

let model_file = '/path/to/xxx.ms';
mindSporeLite.loadModelFromFile(model_file).then((mindSporeLiteModel : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();
  let new_dim = new Array([1,32,32,1]);
  mindSporeLiteModel.resize(modelInputs, new_dim);
})

MSTensor

Represents an MSTensor instance, with properties and APIs defined. It is a special data structure similar to arrays and matrices. It is the basic data structure used in MindSpore Lite network operations.

In the following sample code, you first need to use getInputs() to obtain an MSTensor instance before calling related APIs.

Attributes

System capability: SystemCapability.AI.MindSporeLite

Name Type Readable Writable Description
name string Yes Yes Tensor name. The default value is null.
shape number[] Yes Yes Tensor dimension array. The default value is 0.
elementNum number Yes Yes Length of the tensor dimension array. The default value is 0.
dataSize number Yes Yes Length of tensor data. The default value is 0.
dtype DataType Yes Yes Tensor data type. The default value is 0, indicating TYPE_UNKNOWN.
format Format Yes Yes Tensor data format. The default value is -1, indicating DEFAULT_FORMAT.

Example

let model_file = '/path/to/xxx.ms';
mindSporeLite.loadModelFromFile(model_file).then((mindSporeLiteModel : mindSporeLite.Model) => {
  let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();
  console.log(modelInputs[0].name);
  console.log(modelInputs[0].shape.toString());
  console.log(modelInputs[0].elementNum.toString());
  console.log(modelInputs[0].dtype.toString());
  console.log(modelInputs[0].format.toString());
  console.log(modelInputs[0].dataSize.toString());
})

getData

getData(): ArrayBuffer

Obtains tensor data.

System capability: SystemCapability.AI.MindSporeLite

Return value

Type Description
ArrayBuffer Pointer to the tensor data.

Example

import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
export class Test {
  value:number = 0;
  foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
  }
}
let globalContext = GlobalContext.getContext().getObject("value") as common.UIAbilityContext;
let inputName = 'input_data.bin';
globalContext.resourceManager.getRawFileContent(inputName).then(async (buffer : Uint8Array) => {
  let inputBuffer = buffer.buffer;
  let model_file = '/path/to/xxx.ms';
  let mindSporeLiteModel : mindSporeLite.Model = await mindSporeLite.loadModelFromFile(model_file);
  let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();
  modelInputs[0].setData(inputBuffer);
  mindSporeLiteModel.predict(modelInputs).then((result : mindSporeLite.MSTensor[]) => {
    let output = new Float32Array(result[0].getData());
    for (let i = 0; i < output.length; i++) {
      console.log(output[i].toString());
    }
  })
})

setData

setData(inputArray: ArrayBuffer): void

Sets the tensor data.

System capability: SystemCapability.AI.MindSporeLite

Parameters

Name Type Mandatory Description
inputArray ArrayBuffer Yes Input data buffer of the tensor.

Example

import resourceManager from '@ohos.resourceManager'
import { GlobalContext } from '../GlobalContext';
import mindSporeLite from '@ohos.ai.mindSporeLite';
import common from '@ohos.app.ability.common';
export class Test {
  value:number = 0;
  foo(): void {
    GlobalContext.getContext().setObject("value", this.value);
  }
}
let globalContext = GlobalContext.getContext().getObject("value") as common.UIAbilityContext;
let inputName = 'input_data.bin';
globalContext.resourceManager.getRawFileContent(inputName).then(async (buffer : Uint8Array) => {
  let inputBuffer = buffer.buffer;
  let model_file = '/path/to/xxx.ms';
  let mindSporeLiteModel : mindSporeLite.Model = await mindSporeLite.loadModelFromFile(model_file);
  let modelInputs : mindSporeLite.MSTensor[] = mindSporeLiteModel.getInputs();
  modelInputs[0].setData(inputBuffer);
})

DataType

Tensor data type.

System capability: SystemCapability.AI.MindSporeLite

Name Value Description
TYPE_UNKNOWN 0 Unknown type.
NUMBER_TYPE_INT8 32 Int8 type.
NUMBER_TYPE_INT16 33 Int16 type.
NUMBER_TYPE_INT32 34 Int32 type.
NUMBER_TYPE_INT64 35 Int64 type.
NUMBER_TYPE_UINT8 37 UInt8 type.
NUMBER_TYPE_UINT16 38 UInt16 type.
NUMBER_TYPE_UINT32 39 UInt32 type.
NUMBER_TYPE_UINT64 40 UInt64 type.
NUMBER_TYPE_FLOAT16 42 Float16 type.
NUMBER_TYPE_FLOAT32 43 Float32 type.
NUMBER_TYPE_FLOAT64 44 Float64 type.

Format

Enumerates tensor data formats.

System capability: SystemCapability.AI.MindSporeLite

Name Value Description
DEFAULT_FORMAT -1 Unknown data format.
NCHW 0 NCHW format.
NHWC 1 NHWC format.
NHWC4 2 NHWC4 format.
HWKC 3 HWKC format.
HWCK 4 HWCK format.
KCHW 5 KCHW format.

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