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IshanAryenduIshanAryendu
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CIFAR 10 ExecuTorch model fine-tuning on the Android app (#41)
* Initialized project skeleton * Initialized the app UI in activity_main.xml. * Added the gradle build configurations * Added the image preprocessing methods in the ImageTransformations.kt file * Added the image extraction methods to extract files from the binary files in Cifar10ImageExtractor.kt file * Added the main app logic inside the MainActivity.kt file * Bug fix: Added missing package header in MainActivity.kt file * Bug fix: Updated the target SDK version to ver. 35 for compatibility with newest version of ExecuTorch aar * Removed .idea directory from the repository and updated .gitignore * Added the README file to the repo * Removed unused code from the MainActivity.kt file * Updated the README to include the reference to the CIFAR 10 example in the official ExecuTorch repo * Bug fix: Fixed the filename for the python script in the README * Refactored the code to follow current pattern of the repo * Refactored the code to maintain the current structure of the target repo * Addressed the comments for refactoring the README * Fixed the debug tag in the app * Refactored the README file * Removed unneeded image files from the repository. * Fixed the directory structure * Removed the preexisting files * Refactored and formatted the code * Added the test cases * Clean up: Removed unused theming files from the codebase * Removed the jar file from the repo * Removed the unused theming files * Refactored REDAME to include commands to generate the relevant files and copy the outputs to the destination. * Included the build config file in the README * Removed the check for CMake which is handled by ET installation script
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‎.gitignore‎

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*.bin
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*.model
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*.pte
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*.ptd
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# Xcode
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xcuserdata/
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.build/
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.swiftpm/
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*.xcworkspace/
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*.xcframework/
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*.iml
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.gradle
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/local.properties
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./idea
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/.idea/caches
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/.idea/libraries
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/.idea/modules.xml
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/.idea/workspace.xml
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/.idea/navEditor.xml
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/.idea/assetWizardSettings.xml
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.DS_Store
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/captures
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.externalNativeBuild
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.cxx
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local.properties
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*.aar

‎cifar/android/CifarETTrainingDemo/README.md‎

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# ExecuTorch Model Fine-Tuning on Android App
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In this tutorial, we will be fine-tuning a CIFAR 10 model on an android app using ExecuTorch.
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## Environment Setup
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### Android Environment Setup
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Ensure that your development environment meets the following requirements:
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1. Minimum JDK version: 17
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2. Target Android API level: 34 (`Android 14.0`)
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3. Required Android SDK components:
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- Android SDK Build-Tools 34
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- Android SDK Platform-Tools
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- Android NDK (Side by side)
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- Android SDK Command-line Tools (latest)
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4. Install Android Emulator or connect an Android device
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5. Ensure the following environment variables are set:
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- `JAVA_HOME`
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- `ANDROID_NDK`
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- `ANDROID_SDK`
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**NOTE** For the updated steps for building the dependencies refer to the official repository over [here](https://github.com/pytorch/executorch/blob/main/extension/android/README.md).
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### ExecuTorch Environment Setup
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To ensure better management of Python environments and packages, it is recommended to use a Python environment management tool such as `conda`, `venv`, or `uv`. For this demonstration, we will use `uv` to set up the Python environment.
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To install ExecuTorch in a `uv` Python environment use the following commands:
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```bash
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$ git clone https://github.com/pytorch/executorch.git --recurse-submodules
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$ cd executorch
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# [optional] Setup an environment
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$ uv venv --seed --prompt et --python 3.10
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$ source .venv/bin/activate
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# Install build tools and ExecuTorch pip wheel
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$ ./install_executorch.sh
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# Build ExecuTorch for Android. Output AAR: ./extension/android/executorch_android/build/outputs/aar/executorch_android-debug.aar
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$ ./scripts/build_android_library.sh
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# Fetch the examples
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$ git clone [email protected]:pytorch-labs/executorch-examples.git
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# Copy the ExecuTorch AAR into the libs directory
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$ mkdir -p executorch-examples/cifar/android/CifarETTrainingDemo/app/libs
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$ cp ./extension/android/executorch_android/build/outputs/aar/executorch_android-debug.aar executorch-examples/cifar/android/CifarETTrainingDemo/app/libs/executorch.aar
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# Build the data and models
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$ mkdir -p executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/
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$ python ./extension/training/examples/CIFAR/main.py --data-dir executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/ --model-path executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/cifar10_model.pth --pte-model-path executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/cifar10_model.pte --split-pte-model-path executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/cifar10_model_pte_only.pte --save-pt-json executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/cifar10_pt.json --save-et-json executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/cifar10_et.json --ptd-model-dir executorch-examples/cifar/android/CifarETTrainingDemo/app/src/main/assets/ --epochs 5 --fine-tune-epochs 10
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```
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If you run into errors for sdk path, complete the above steps in the [Trouble Shooting](#trouble-shooting) section before proceeding.
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## Creation of Android App
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1. Start with a clone of this repository and open the project in Android Studio executorch-examples/cifar/android/CifarETTrainingDemo/app/build.gradle.kts.
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2. Set the minimum SDK version to `API 34`.
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3. Wait for the Gradle sync to complete.
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4. Click on run to proceed: ![](./images/Pasted%20image%2020250709170837.png)
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5. Click on the fine-tune button and the training begins for `150` epochs![[Pasted image 20250709171210.png]]
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**Note:** The training parameters can be tweaked in `MainActivity.kt`
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### Summary:
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We trained the PyTorch model for `1 epoch` and exported the `.pte` and `.ptd` files. We started with training loss of `2.159132883071899`, training accuracy of `18%`, testing loss of `2.1072397136688235`, and testing accuracy of `29%`
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```log
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2025-07-09 17:11:46.309 13277-13277 ExecuTorchApp com.example.democifar10 D Starting Epoch 1/150
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2025-07-09 17:11:46.309 13277-13277 ExecuTorchApp com.example.democifar10 D Total images to be trained: 500, Number of batches: 125
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2025-07-09 17:11:47.237 13277-13428 EGL_emulation com.example.democifar10 D app_time_stats: avg=7.23ms min=2.75ms max=25.70ms count=60
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2025-07-09 17:11:47.715 13277-13277 ExecuTorchApp com.example.democifar10 D Epoch [1/150] Loss: 2.159132883071899, Accuracy: 18%, Time: 1.41 s, Time per image: 2.81 ms
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2025-07-09 17:11:47.715 13277-13277 ExecuTorchApp com.example.democifar10 D Starting evaluation
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2025-07-09 17:11:47.715 13277-13277 ExecuTorchApp com.example.democifar10 D Evaluating model on 100 test images (25 batches) out of 100 total images
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2025-07-09 17:11:47.989 13277-13277 ExecuTorchApp com.example.democifar10 D Evaluation complete - Loss: 2.1072397136688235, Accuracy: 29.0%, Time: 0.27 s, Time per image: 2.73 ms
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```
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We reached a training loss of `1.7837489886283875`, training accuracy of `35%`, testing loss of `2.0501016211509704`, and testing accuracy of `38%` after `150 epochs`
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```log
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2025-07-09 17:13:59.889 13277-13277 ExecuTorchApp com.example.democifar10 D Starting Epoch 150/150
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2025-07-09 17:13:59.889 13277-13277 ExecuTorchApp com.example.democifar10 D Total images to be trained: 500, Number of batches: 125
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2025-07-09 17:14:00.666 13277-13277 ExecuTorchApp com.example.democifar10 D Epoch [150/150] Loss: 1.7837489886283875, Accuracy: 35%, Time: 0.78 s, Time per image: 1.56 ms
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2025-07-09 17:14:00.666 13277-13277 ExecuTorchApp com.example.democifar10 D Starting evaluation
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2025-07-09 17:14:00.666 13277-13277 ExecuTorchApp com.example.democifar10 D Evaluating model on 100 test images (25 batches) out of 100 total images
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2025-07-09 17:14:00.809 13277-13277 ExecuTorchApp com.example.democifar10 D Evaluation complete - Loss: 1.7236163129806519, Accuracy: 38%, Time: 0.67 s, Time per image: 1.35 ms
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```
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### Trouble Shooting
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Check if the `local.properties` file is present in the `extension/android` directory:
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```bash
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$ cat ./extension/android/local.properties
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```
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**NOTE:** If this file (`local.properties`) is missing, the build process will fail because the script can't retrieve the path for the android sdk from the env variables. If you encounter this issue, please follow the following steps:
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```bash
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$ touch ./extension/android/local.properties
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$ vim ./extension/android/local.properties
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# Add the path to your sdk directory into this file like: sdk.dir=/Users/<USERNAME>/Library/Android/sdk
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```

‎cifar/android/CifarETTrainingDemo/app/.gitignore‎

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/build

‎cifar/android/CifarETTrainingDemo/app/build.gradle.kts‎

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plugins {
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alias(libs.plugins.android.application)
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alias(libs.plugins.kotlin.android)
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alias(libs.plugins.kotlin.compose)
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}
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android {
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namespace = "com.example.democifar10"
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compileSdk = 35
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defaultConfig {
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applicationId = "com.example.democifar10"
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minSdk = 35
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targetSdk = 35
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versionCode = 1
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versionName = "1.0"
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testInstrumentationRunner = "androidx.test.runner.AndroidJUnitRunner"
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}
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buildTypes {
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release {
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isMinifyEnabled = false
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proguardFiles(
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getDefaultProguardFile("proguard-android-optimize.txt"),
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"proguard-rules.pro"
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)
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}
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}
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compileOptions {
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sourceCompatibility = JavaVersion.VERSION_1_8
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targetCompatibility = JavaVersion.VERSION_1_8
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}
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kotlinOptions {
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jvmTarget = "1.8"
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}
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buildFeatures {
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compose = true
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}
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composeOptions {
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kotlinCompilerExtensionVersion = "1.5.1"
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}
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packaging {
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resources {
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excludes += "/META-INF/{AL2.0,LGPL2.1}"
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}
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}
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}
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dependencies {
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implementation(libs.androidx.core.ktx)
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implementation(libs.androidx.lifecycle.runtime.ktx)
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implementation(libs.androidx.activity.compose)
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implementation(platform(libs.androidx.compose.bom))
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implementation("androidx.appcompat:appcompat:1.6.1")
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implementation(libs.androidx.ui)
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implementation(libs.androidx.ui.graphics)
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implementation(libs.androidx.ui.tooling.preview)
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implementation(libs.androidx.material3)
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implementation(fileTree(mapOf("dir" to "libs", "include" to listOf("*.jar", "*.aar"))))
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// Add SoLoader dependency for PyTorch native library loading
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implementation("com.facebook.soloader:soloader:0.10.5")
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// Add Facebook JNI dependency required by executorch
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implementation("com.facebook.fbjni:fbjni:0.5.1")
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testImplementation(libs.junit)
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androidTestImplementation(libs.androidx.junit)
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androidTestImplementation(libs.androidx.espresso.core)
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androidTestImplementation(platform(libs.androidx.compose.bom))
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androidTestImplementation(libs.androidx.ui.test.junit4)
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debugImplementation(libs.androidx.ui.tooling)
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debugImplementation(libs.androidx.ui.test.manifest)
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}

‎cifar/android/CifarETTrainingDemo/app/proguard-rules.pro‎

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# Add project specific ProGuard rules here.
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# You can control the set of applied configuration files using the
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# proguardFiles setting in build.gradle.
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#
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# For more details, see
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# http://developer.android.com/guide/developing/tools/proguard.html
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# If your project uses WebView with JS, uncomment the following
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# and specify the fully qualified class name to the JavaScript interface
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# class:
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#-keepclassmembers class fqcn.of.javascript.interface.for.webview {
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# public *;
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#}
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# Uncomment this to preserve the line number information for
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# debugging stack traces.
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#-keepattributes SourceFile,LineNumberTable
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# If you keep the line number information, uncomment this to
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# hide the original source file name.
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#-renamesourcefileattribute SourceFile

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