wafrat - wafrat (Page 6)

Survey of Keras's image related generators

In François Chollet's Deep learning with Python, he teaches how to build image classification models using ImageDataGenerators. Let's look into how these are made and how to use them. tf.keras.preprocessing.image.ImageDataGeneratorGenerate batches of tensor image data with real-time data augmentation.TensorFlow Basic usage Use images in a

tensorflow

Plotting discrimination thresholds in TensorFlow

scikit-learn can render precision, recall and F1 score depending on thresholds in a chart. I wanted the same to evaluate my binary classifier made with TensorFlow. See how it looks like on scikit-learn. O(data × number of thresholds) Generating thresholds In order to implement it, I had to figure out

tensorflow

Installing TensorFlow 2.5 and Jupyter Lab on Mac with M1

Last month, I finally painstakingly installed TensorFlow 2.4 and Jupyter Lab on my Mac with M1 (see the blog post). It worked nicely: 10 times faster than Colab, but also had a few issues like working only with Python 3.8, having to manually downgrade some packages such as

python

How to compute things in parallel in Python

I had a loop that could be parallelized and wanted to take advantage of my CPU cores. A quick search led me to https://docs.python.org/3/library/asyncio-task.html#running-tasks-concurrently. It looked simple enough: define your methods as async, then run them with a gather. However, I realized

numpy

Fixing `TypeError: only integer scalar arrays can be converted to a scalar index`

This will be a short post. I was trying to concatenate two numpy arrays, when I got this exception: TypeError: only integer scalar arrays can be converted to a scalar index I was following https://numpy.org/doc/stable/reference/generated/numpy.concatenate.html. It turned out I misread the

machine learning

Displaying a confusion matrix in TensorFlow

I recently started dabbling in TensorFlow by training an image classifier. My classifier has a few classes, and instead of blindly judging its accuracy, I decided to look at the confusion matrix to see which classes it recognized well and which it didn't. Multiclass classifier In TensorFlow, there's a function

flutter

Profiling a Flutter app

Today I ran into some performance issue when I used my image gallery app on a folder of 17k images. Lots of jank. So I decided to use the Flutter profiler for the first time. I started from the Flutter performance profiling page. Flutter performance profilingDiagnosing UI performance issues in

flutter

Fixing `Unable to load asset: FontManifest.json` when using golden_toolkit

I recently started using eBay's golden_toolkit for screenshot tests instead of Flutter's built-in matchesGoldenFile. My main issue with the built-in function was that it would use the Ahem font, which is all blocks. It makes it much harder to see if your app rendered correctly. In the past, I

firestore

How come Firestore won't write anything anymore?

I had been scratching my head since last night. For some reason, when creating lots of new documents, only the first batch would show up in my UI. I'd put a print before and after the await batch.commit() and see that it would hang. What was going on? It

Using Firebase in Flutter on macOS

Firebase Auth Authentication methods I typically use Google Sign In for my projects, but as you can see on https://pub.dev/packages/google_sign_in, it only supports Android, iOS and Web, and there is no GitHub issue tracking Desktop. Phone authentication also required extra steps, and it didn't

tensorflow

TensorFlow reference docs

In a previous post, I collected reference documentation for Python at http://blog.wafrat.com/finding-the-python-reference-docs/. Let's do the same for TensorFlow: * https://www.tensorflow.org/api_docs/python/tf/dtypes/DType * https://keras.io/api/preprocessing/image/ * https://www.tensorflow.org/api_docs/python/tf/keras/Model#fit * https:

flutter

Getting stack traces for published Flutter apps

flutter web

Setting up Sentry for Flutter Web

On the official Flutter docs, they say you can run flutter build web to compile for a release, and it'll generate everything you need, including source maps. Build and release a web appHow to prepare for and release a web app.Flutter Logo However this is not the case. Also,

flutter

GridView with fixed height in Flutter

I wanted to convert a ListView into a GridView so that it would show more information on a large screen such as Web. My ListView code looked like this: return ListView.builder( physics: scrollable ? null : NeverScrollableScrollPhysics(), shrinkWrap: shrinkWrap, padding: EdgeInsets.only(top: 16.0), itemCount: words.length, itemBuilder: (context, index)

flutter

Migrating a large Flutter project to null safety

According to the guide at https://dart.dev/null-safety/migration-guide, migrating to null safety is straightforward. Let's try it on a large project. So today I switched the sdk version to 2.12 in my pubspec.yaml, and 300+ compilation errors appeared. I tried the migration tool: % dart migrate Migrating

flutter

On the importance of the Flutter environment sdk version

Yesterday I made a quick update to my app. All the code compiled and all the tests succeeded, so I published an update. This morning, I wake up to a half broken app. What happened? The simplified snippet was: await Firebase.initializeApp(); final instance = FirebaseFirestore.instance; final transformer = StreamTransformer.fromHandlers(

dart

Working with JSON in Dart

Working with JSON in Dart is relatively easy, but there are still a few caveats. Handling dynamic types There's a page dedicated to JSON in Dart at https://dart.dev/guides/json. The first way is to use dart:convert's jsonDecode(String) => dynamic. I was trying to deserialize this kind

dart

Map through a list with index in Dart

In Javascript, it's easy to map through a list with the value and index. In Dart, you only get the value, but not the index. One of the top results on Google for this issue is this StackOverflow post from 2 years ago: https://stackoverflow.com/questions/54898767/enumerate-or-map-through-a-list-with-index-and-value-in-dart. They

flutter

Upgrading pre 1.12 Android projects based on Kotlin

My old Flutter app has been complaining I need to do this migration for a while. Today I finally decided to do it. flutter/flutterFlutter makes it easy and fast to build beautiful apps for mobile and beyond. - flutter/flutterGitHubflutter Based on the criteria listed in the documentation, I

flutter

My new Flutter project is stuck in assembleGradle

I created a new project by running flutter create .. Then I modified the Android app's package by modifying it in: * android/app/build.gradle * android/app/src/main/AndroidManifest.xml I also integrated Firestore to it, and added an Android app there, with the new package name. Finally I ran

flutter

Fixing `com.android.builder.dexing.DexArchiveMergerException: Error while merging dex archives: The number of method references in a .dex file cannot exceed 64K.` in Flutter when using Firestore

I created a new project, integrated Firestore to it, and on the first run, I got this error. A quick search got me to https://github.com/flutter/flutter/issues/21005. The error also shares this link: https://developer.android.com/tools/building/multidex.html. The relevant section is "Configure

ghost

Setting up a self-hosted Ghost blog in 2021

A lot has changed since I set up this blog back in 2017. Now, DigitalOcean has created a way to get started much faster and with less hassle. See how I did it manually back then at http://blog.wafrat.com/setting-up-the-blog/. This blog post replaces the whole section entitled

tensorflow

Use TensorBoard in Colab to track the training of a text classification model

I just read Chapter 7 of Chollet's Deep learning with Python, and it introduces TensorBoard as a way to visualize metrics in real-time during training and embeddings. The goal In order to try it out, I decided to make a text classification model that predicts the category of a news

flutter web

Fixing `Caught error: Unsupported operation: Platform._version` when using HttpClient in Flutter Web

While porting my Flutter mobile app to Web, I ran into this exception: Caught error: Unsupported operation: Platform._version It originated from dart-sdk/lib/_http/http.dart, more precisely as soon as I instantiate dart io's HttpClient. Starting from dart io's HttpClient After reading a few StackOverflow posts, it turns

linux

Resizing swap

I use small Digital Ocean virtual machines, and they come with little RAM and little drive space. I originally allocated 4 GB for the swap, but now I want to reduce it to 2 GB. Initially to prevent the server from going out of RAM and randomly killing processes like