The new Knet release is all about iterators: iterators for minibatching, iterators for training, iterators for monitoring, convergence etc. Why am I so excited about iterators all of a sudden? Allow me to explain:
Knet has used iterators for data generation since 2015. That was about it until recently when I was looking for a way to improve the training interface. See, at the core of every deep learning project there is a training loop that looks like this:
function train(model,data)
for (x,y) in data
# improve model parameters so model(x) approaches y
end
end
And these things can run for hours or days. You want the user to have full control of this loop: how many iterations to go, how to detect convergence and quit, how to monitor progress, how to take model snapshots or measure dev accuracy every n iterations etc.
My original (non)solution was to write a new `train` function for every experiment. Why restrict the user with a bad interface when they can write their own 5 line loop? (of course then why write any package at all but that's another discussion).
My next (pseudo)solution was to provide a `train` function with lots of keyword arguments. I soon gave up on that idea when it became clear that I was on my way to implementing a Turing complete programming language using keyword arguments.
Then I thought I had a brilliant flash of insight based on callback functions. See if `train` just accepts a callback function that gets called inside the for loop, the user can implement any behavior:
function train(model,data,callback)
for (x,y) in data
callback() || break
# improve model parameters so model(x) approaches y
end
end
You want to display a progress bar, do something every n iterations, or quit after N iterations? Just implement some callback function with state and you are all set! Brilliant? Everybody hated it. Including me. It turns out callback functions are awkward to write and do not lead to very readable code.
Then finally I rediscovered iterators and iterators that wrap other iterators (inspired by Tqdm.jl). I knew iterators can be these lazy collections that produce their next element only when asked. (Here is a summary with doc links to refresh your memory). See, once you implement the training loop as an iterator you can pause, restart and terminate it whenever you want:
train(model,data) = ((update model and return loss) for (x,y) in data)
What I realized iterators also do is turn the for loop inside out! Make its guts visible so one has explicit control: You can monitor and display its progress, take snapshots or whatever all with very explicit and readable code. Here are some actual examples from Knet v1.2.0. (`sgd` is a train iterator, f is the model, d is the data):
* To display a progress bar use progress(sgd(f,d)).
* To run until convergence use converge(sgd(f,cycle(d))).
* To run multiple epochs use sgd(f,repeat(d,n)).
* To run a given number of iterations use sgd(f,take(cycle(d),n)).
* To do a task every n iterations use: (task(x) for x in every(n, sgd(f,cycle(d)))).
Each of the functions like `progress`, `converge`, `sgd` etc. take and return iterators. So they can be composed like crazy. Here is how to (1) train a model on dtrn, (2) measuring loss on dtst every 100 iterations, (3) quitting when dtst performance converges, and (4) displaying a progress bar from the Knet tutorial:
a = adam(model,cycle(dtrn))
b = (model(dtst) for _ in every(100,a))
c = converge(b, alpha=0.1)
progress!(c, alpha=1)
The code reads like the English description! Imagine trying to implement this using keyword arguments or callback functions... and that is why I am excited about iterators.
Notes:
* the more nitpicky reader will probably point out that I should have called these things generators or coroutines or streams or something rather than iterators, but you get the idea.
* every(n,itr) = (x for (i,x) in enumerate(itr) if i%n == 0) should be a Julia primitive! (Thank you @CarloLucibello for pointing out that `IterTools.takenth` does the same thing.)
* @lostella has a wonderful post on iterators.
* Here are the relevant links in Julia docs: Interfaces, Collections, Iteration Utilities and Generator expressions.
* Here is a link to the discussion on Julia discourse.
Alan Edelman, Deniz Yuret
Jan 7-11, 2019. 11:00am-12:30pm. Room: 2-135.
Description: The course will consist of five hands-on tutorials giving the students practical experience in programming, training, evaluating and benchmarking deep learning models in Julia. While other machine learning libraries can meet many needs, for innovators who want to go innovate beyond the ordinary models, the expressivity of Julia has no equal. After a brief introduction to the Julia programming language we will cover linear models, multi-layer perceptrons, convolutional and recurrent neural networks. Through these examples the students will be exposed to the concepts of optimization with stochastic gradient descent (backpropagation); data normalization and minibatching; overfitting and regularization; model architectures and sample efficiency.
Prerequisites: Familiarity with programming, probability, calculus and linear algebra.
An agent must first follow navigation instructions in a real-life visual urban environment to a goal position, and then identify in the observed image a location described in natural language to find a hidden object. The data contains 9,326 examples of English instructions and spatial descriptions paired with demonstrations.
Visual commonsense reasoning dataset. Visual Commonsense Reasoning (VCR) is a new task and large-scale dataset for cognition-level visual understanding. With one glance at an image, we can effortlessly imagine the world beyond the pixels (e.g. that [person1] ordered pancakes). While this task is easy for humans, it is tremendously difficult for today's vision systems, requiring higher-order cognition and commonsense reasoning about the world. We formalize this task as Visual Commonsense Reasoning. In addition to answering challenging visual questions expressed in natural language, a model must provide a rationale explaining why its answer is true.
290k multiple choice questions
290k correct answers and rationales: one per question
110k images
Counterfactual choices obtained with minimal bias, via our new Adversarial Matching approach
Answers are 7.5 words on average; rationales are 16 words.
High human agreement (>90%)
Scaffolded on top of 80 object categories from COCO
Is now (as of Dec 3, 2018) available for download!
The data contains 107,296 examples of English sentences paired with web photographs. The task is to determine whether a natural language caption is true about a photograph. The data was collected through crowdsourcings, and solving the task requires reasoning about sets of objects, comparisons, and spatial relations. There are two related corpora: NLVR, with synthetically generated images, and NLVR2, which includes natural photographs.
In this paper, we introduce How2, a multimodal collection of instructional videos with English subtitles and crowdsourced Portuguese translations. We also present integrated sequence-to-sequence baselines for machine translation, automatic speech recognition, spoken language translation, and multimodal summarization. By making available data and code for several multimodal natural language tasks, we hope to stimulate more research on these and similar challenges, to obtain a deeper understanding of multimodality in language processing. The corpus consists of around 80,000 instructional videos (about 2,000 hours) with associated English sub-titles and summaries. About 300 hours have also been translated into Portuguese using crowd-sourcing, and used during the JSALT 2018 Workshop.
TVQA: Localized, Compositional Video Question Answering. TVQA is a large-scale video QA dataset based on 6 popular TV shows (Friends, The Big Bang Theory, How I Met Your Mother, House M.D., Grey's Anatomy, Castle). It consists of 152.5K QA pairs from 21.8K video clips, spanning over 460 hours of video. The questions are designed to be compositional, requiring systems to jointly localize relevant moments within a clip, comprehend subtitles-based dialogue, and recognize relevant visual concepts.
TEMPOral reasoning in video and language (TEMPO) dataset. Localizing moments in a longer video via natural language queries is a new, challenging task at the intersection of language and video understanding. Though moment localization with natural language is similar to other language and vision tasks like natural language object retrieval in images, moment localization offers an interesting opportunity to model temporal dependencies and reasoning in text. Our dataset consists of two parts: a dataset with real videos and template sentences (TEMPO - Template Language) which allows for controlled studies on temporal language, and a human language dataset which consists of temporal sentences annotated by humans (TEMPO - Human Language).
RecipeQA is a dataset for multimodal comprehension of cooking recipes. It consists of over 36K question-answer pairs automatically generated from approximately 20K unique recipes with step-by-step instructions and images. Each question in RecipeQA involves multiple modalities such as titles, descriptions or images, and working towards an answer requires (i) joint understanding of images and text, (ii) capturing the temporal flow of events, and (iii) making sense of procedural knowledge.
We propose to decompose instruction execution to goal prediction and action generation. We design a model that maps raw visual observations to goals using LINGUNET, a language-conditioned image generation network, and then generates the actions required to complete them. Our model is trained from demonstration only without external resources. To evaluate our approach, we introduce two benchmarks for instruction following: LANI, a navigation task; and CHAI, where an agent executes household instructions.
Two agents, a "tourist" and a "guide", interact with each other via natural language in order to have the tourist navigate towards the correct location. The guide has access to a map and knows the target location but not the tourist location, while the tourist does not know the way but can navigate in a 360-degree street view environment. The task involves "perception" for the tourist observing the world, "action" for the tourist to navigate through the environment, and "interactive dialogue" for the tourist and guide to work towards their common goal.
We make available Conceptual Captions, a new dataset consisting of ~3.3M images annotated with captions. In contrast with the curated style of other image caption annotations, Conceptual Caption images and their raw descriptions are harvested from the web, and therefore represent a wider variety of styles. More precisely, the raw descriptions are harvested from the Alt-text HTML attribute associated with web images. To arrive at the current version of the captions, we have developed an automatic pipeline that extracts, filters, and transforms candidate image/caption pairs, with the goal of achieving a balance of cleanliness, informativeness, fluency, and learnability of the resulting captions.
Automatic Understanding of Visual Advertisements: A large annotated dataset of image and video ads. In this dataset, we provide over 64,000 ad images annotated with the topic of the ad (e.g. the product or topic, in case of public service announcements), the sentiment that the ad provokes, any symbolic references that the ad makes (e.g. an owl symbolizes wakefulness, ice symbolizes freshness, etc.), including bounding boxes containing the physical content that alludes symbolically to concepts outside of the ad, and questions and answers about the meaning of the ad ("What should I do according to the ad? Why should I do it, according to the ad?")
VizWiz is proposed to empower a blind person to directly request in a natural manner what (s)he would like to know about the surrounding physical world.
We present CHALET, a 3D house simulator with support for navigation and manipulation. CHALET includes 58 rooms and 10 house configuration, and allows to easily create new house and room layouts. CHALET supports a range of common household activities, including moving objects, toggling appliances, and placing objects inside closeable containers. The environment and actions available are designed to create a challenging domain to train and evaluate autonomous agents, including for tasks that combine language, vision, and planning in a dynamic environment.
CoDraw: Visual dialog for collaborative drawing. In this work, we propose a goal-driven collaborative task that contains vision, language, and action in a virtual environment as its core components. Specifically, we develop a collaborative `Image Drawing' game between two agents, called CoDraw. Our game is grounded in a virtual world that contains movable clip art objects. Two players, Teller and Drawer, are involved. The Teller sees an abstract scene containing multiple clip arts in a semantically meaningful configuration, while the Drawer tries to reconstruct the scene on an empty canvas using available clip arts. The two players communicate via two-way communication using natural language. We collect the CoDraw dataset of ~10K dialogs consisting of 138K messages exchanged between a Teller and a Drawer from Amazon Mechanical Turk (AMT). We analyze our dataset and present three models to model the players' behaviors, including an attention model to describe and draw multiple clip arts at each round. The attention models are quantitatively compared to the other models to show how the conventional approaches work for this new task. We also present qualitative visualizations.
We introduce Interactive Question Answering (IQA), the task of answering questions that require an autonomous agent to interact with a dynamic visual environment. IQA presents the agent with a scene and a question, like: "Are there any apples in the fridge?" The agent must navigate around the scene, acquire visual understanding of scene elements, interact with objects (e.g. open refrigerators) and plan for a series of actions conditioned on the question.
We present a new AI task -- Embodied Question Answering (EmbodiedQA) -- where an agent is spawned at a random location in a 3D environment and asked a question ("What color is the car?"). In order to answer, the agent must first intelligently navigate to explore the environment, gather information through first-person (egocentric) vision, and then answer the question ("orange").
This challenging task requires a range of AI skills -- active perception, language understanding, goal-driven navigation, commonsense reasoning, and grounding of language into actions. In this work, we develop the environments, end-to-end-trained reinforcement learning agents, and evaluation protocols for EmbodiedQA.
R2R is the first benchmark dataset for visually-grounded natural language navigation in real buildings. The dataset requires autonomous agents to follow human-generated navigation instructions in previously unseen buildings, as illustrated in the demo above. For training, each instruction is associated with a Matterport3D Simulator trajectory. 22k instructions are available, with an average length of 29 words. There is a test evaluation server for this dataset available at EvalAI.
We introduce FigureQA, a visual reasoning corpus of over one million question-answer pairs grounded in over 100,000 images. The images are synthetic, scientific-style figures from five classes: line plots, dot-line plots, vertical and horizontal bar graphs, and pie charts. We formulate our reasoning task by generating questions from 15 templates; questions concern various relationships between plot elements and examine characteristics like the maximum, the minimum, area-under-the-curve, smoothness, and intersection. To resolve, such questions often require reference to multiple plot elements and synthesis of information distributed spatially throughout a figure. To facilitate the training of machine learning systems, the corpus also includes side data that can be used to formulate auxiliary objectives. In particular, we provide the numerical data used to generate each figure as well as bounding-box annotations for all plot elements. We study the proposed visual reasoning task by training several models, including the recently proposed Relation Network as a strong baseline. Preliminary results indicate that the task poses a significant machine learning challenge. We envision FigureQA as a first step towards developing models that can intuitively recognize patterns from visual representations of data.
In this work, we design a cooperative game - GuessWhich - to measure human-AI team performance in the specific context of the AI being a visual conversational agent. GuessWhich involves live interaction between the human and the AI. The AI, which we call ALICE, is provided an image which is unseen by the human. Following a brief description of the image, the human questions ALICE about this secret image to identify it from a fixed pool of images.
We measure performance of the human-ALICE team by the number of guesses it takes the human to correctly identify the secret image after a fixed number of dialog rounds with ALICE.
GuessWhat?! is a cooperative two-player guessing game. The goal of the game is to locate an unknown object in a rich image scene by asking a sequence of questions. The aim of this project is to facilitate research in combining visual understanding, natural language processing and cooperative agent interaction.
TQA: Textbook Question Answering. The TQA dataset encourages work on the task of Multi-Modal Machine Comprehension (M3C) task. The M3C task builds on the popular Visual Question Answering (VQA) and Machine Comprehension (MC) paradigms by framing question answering as a machine comprehension task, where the context needed to answer questions is provided and composed of both text and images. The dataset constructed to showcase this task has been built from a middle school science curriculum that pairs a given question to a limited span of knowledge needed to answer it.
MarioQA: Answering Questions by Watching Gameplay Videos. From a total of 13 hours of gameplays, we collect 187,757 examples with automatically generated QA pairs. There are 92,874 unique QA pairs and each video clip contains 11.3
events in average. There are 78,297, 64,619 and 44,841 examples in NT, ET and HT, respectively. Note that there
are 3.5K examples that can be answered using a single frame of video; the portion of such examples is only less than
2%. The other examples are event-centric; 98K examples require to focus on a single event out of multiple ones while
86K need to recognize multiple events for counting (55K) or identifying their temporal relationships (44K). Note that
there are instances that belong to both cases.
Visual Dialog is a novel task that requires an AI agent to hold a meaningful dialog with humans in natural, conversational language about visual content. Specifically, given an image, a dialog history, and a follow-up question about the image, the agent has to answer the question.
We construct a dataset, COMICS, that consists of over 1.2 million panels (120 GB) paired with automatic textbox transcriptions. An in-depth analysis of COMICS demonstrates that neither text nor image alone can tell a comic book story, so a computer must understand both modalities to keep up with the plot. We introduce three cloze-style tasks that ask models to predict narrative and character-centric aspects of a panel given n preceding panels as context.
Sequential CONtext-dependent Execution dataset: The task in the SCONE dataset is to execute a sequence of actions according to the instructions. Each scenario contains a world with several objects (e.g., beakers), each with different properties (e.g., chemical colors and amounts). Given 5 sequential instructions in human language (e.g., "Pour from the first beaker into the yellow beaker" or "Mix it"), the system has to predict the final world state.
Dataset where humans give instructions to robots using unrestricted natural language commands to build complex goal configurations in a blocks world. Example instruction from a sequence: "move the nvidia block to the right of the hp block".
Visual Storytelling Challenge (NAACL 2018). We introduce the first dataset for sequential vision-to-language, and explore how this data may be used for the task of visual storytelling. The dataset includes 81,743 unique photos in 20,211 sequences, aligned to descriptive and story language. VIST is previously known as "SIND", the Sequential Image Narrative Dataset (SIND).
AI2D is a dataset of illustrative diagrams for research on diagram understanding and associated question answering. Each diagram has been densely annotated with object segmentations, diagrammatic and text elements. Each diagram has a corresponding set of questions and answers.
We introduce the MovieQA dataset which aims to evaluate automatic story comprehension from both video and text. The data set consists of almost 15,000 multiple choice question answers obtained from over 400 movies and features high semantic diversity. Each question comes with a set of five highly plausible answers; only one of which is correct. The questions can be answered using multiple sources of information: movie clips, plots, subtitles, and for a subset scripts and DVS.
VQA is a new dataset containing open-ended questions about images. These questions require an understanding of vision, language and commonsense knowledge to answer.
265,016 images (COCO and abstract scenes)
At least 3 questions (5.4 questions on average) per image
10 ground truth answers per question
3 plausible (but likely incorrect) answers per question
ReferItGame: Referring to Objects in Photographs of Natural Scenes. In this paper we introduce a new game to crowd-source natural language referring expressions. By designing a two player game, we can both collect and verify referring expressions directly within the game. To date, the game has produced a dataset containing 130,525 expressions, referring to 96,654 distinct objects, in 19,894 photographs of natural scenes.
We have created an image caption corpus consisting of 158,915 crowd-sourced captions describing 31,783 images. This is an extension of our previous Flickr 8k Dataset. The new images and captions focus on people involved in everyday activities and events
We introduce a new benchmark collection for sentence-based image description and search, consisting of 8,000 images that are each paired with five different captions which provide clear descriptions of the salient entities and events.
We describe
our experience in creating corpora of
images annotated with multiple one-sentence
descriptions on MTurk and explore the effectiveness
of different quality control strategies
for collecting linguistic data using Mechanical
MTurk. We find that the use of a qualification
test provides the highest improvement
of quality, whereas refining the annotations
through follow-up tasks works rather poorly.
Using our best setup, we construct two image
corpora, totaling more than 40,000 descriptive
captions for 9000 images.
A corpus of 786 route instructions gathered from six people in three large-scale virtual indoor environments. Thirty six other people followed these instructions and rated them for quality. These human participants finished at the intended destination on 69% of the trials. State of the art is 35.4%. The instructions were later split into sentences and corresponding segments. State of the art at sentence level is 73%. Sample sentences: "With the wall on your left, walk forward", "Go two intersections down the pink hallway".
Since we originally proposed the need for a first-class language, compiler and ecosystem for machine learning (ML), there have been plenty of interesting developments in the field. Not only have the tradeoffs in existing systems, such as TensorFlow and PyTorch, not been resolved, but they are clearer than ever now that both frameworks contain distinct “static graph” and “eager execution” interfaces. Meanwhile, the idea of ML models fundamentally being differentiable algorithms – often called differentiable programming – has caught on...
The book makes great points, especially regarding the faulty incentive structure of scientists and the charade of “research proposals” for funding. My only qualm is that the reader may come away thinking there are no objective measures of goodness for models, which is not true. Statistical learning theory, Bayesian Occam factors, algorithmic complexity etc. each grapple with this problem, yet not much of this is mentioned.
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