Connect with us

AI

Building a medical image search platform on AWS

Improving radiologist efficiency and preventing burnout is a primary goal for healthcare providers. A nationwide study published in Mayo Clinic Proceedings in 2015 showed radiologist burnout percentage at a concerning 61% [1]. In additon, the report concludes that “burnout and satisfaction with work-life balance in US physicians worsened from 2011 to 2014. More than half […]

Published

on

Improving radiologist efficiency and preventing burnout is a primary goal for healthcare providers. A nationwide study published in Mayo Clinic Proceedings in 2015 showed radiologist burnout percentage at a concerning 61% [1]. In additon, the report concludes that “burnout and satisfaction with work-life balance in US physicians worsened from 2011 to 2014. More than half of US physicians are now experiencing professional burnout.”[2] As technologists, we’re looking for ways to put new and innovative solutions in the hands of physicians to make them more efficient, reduce burnout, and improve care quality.

To reduce burnout and improve value-based care through data-driven decision-making, Artificial Intelligence (AI) can be used to unlock the information trapped in the vast amount of unstructured data (e.g. images, texts, and voice) and create clinically actionable knowledge base. AWS AI services can derive insights and relationships from free-form medical reports, automate the knowledge sharing process, and eventually improve personalized care experience.

In this post, we use Convolutional Neural Networks (CNN) as a feature extractor to convert medical images into a one-dimensional feature vector with a size of 1024. We call this process medical image embedding. Then we index the image feature vector using the K-nearest neighbors (KNN) algorithm in Amazon Elasticsearch Service (Amazon ES) to build a similarity-based image retrieval system. Additionally, we use the AWS managed natural language processing (NLP) service Amazon Comprehend Medical to perform named entity recognition (NER) against free text clinical reports. The detected named entities are also linked to medical ontology, ICD-10-CM, to enable simple aggregation and distribution analysis. The presented solution also includes a front-end React web application and backend GraphQL API managed by AWS Amplify and AWS AppSync, and authentication is handled by Amazon Cognito.

After deploying this working solution, the end-users (healthcare providers) can search through a repository of unstructured free text and medical images, conduct analytical operations, and use it in medical training and clinical decision support. This eliminates the need to manually analyze all the images and reports and get to the most relevant ones. Using a system like this improves the provider’s efficiency. The following graphic shows an example end result of the deployed application.

Dataset and architecture

We use the MIMIC CXR dataset to demonstrate how this working solution can benefit healthcare providers, in particular, radiologists. MIMIC CXR is a publicly available database of chest X-ray images in DICOM format and the associated radiology reports as free text files[3]. The methods for data collection and the data structures in this dataset have been well documented and are very detailed [3]. Also, this is a restricted-access resource. To access the files, you must be a registered user and sign the data use agreement. The following sections provide more details on the components of the architecture.

The following diagram illustrates the solution architecture.

The architecture is comprised of the offline data transformation and online query components. The offline data transformation step, the unstructured data, including free texts and image files, is converted into structured data.

Electronic Heath Record (EHR) radiology reports as free text are processed using Amazon Comprehend Medical, an NLP service that uses machine learning to extract relevant medical information from unstructured text, such as medical conditions including clinical signs, diagnosis, and symptoms. The named entities are identified and mapped to structured vocabularies, such as ICD-10 Clinical Modifications (CMs) ontology. The unstructured text plus structured named entities are stored in Amazon ES to enable free text search and term aggregations.

The medical images from Picture Archiving and Communication System (PACS) are converted into vector representations using a pretrained deep learning model deployed in an Amazon Elastic Container Service (Amazon ECS) AWS Fargate cluster. Similar visual search on AWS has been published previously for online retail product image search. It used an Amazon SageMaker built-in KNN algorithm for similarity search, which supports different index types and distance metrics.

We took advantage of the KNN for Amazon ES to find the k closest images from a feature space as demonstrated on the GitHub repo. KNN search is supported in Amazon ES version 7.4+. The container running on the ECS Fargate cluster reads medical images in DICOM format, carries out image embedding using a pretrained model, and saves a PNG thumbnail in an Amazon Simple Storage Service (Amazon S3) bucket, which serves as the storage for AWS Amplify React web application. It also parses out the DICOM image metadata and saves them in Amazon DynamoDB. The image vectors are saved in an Elasticsearch cluster and are used for the KNN visual search, which is implemented in an AWS Lambda function.

The unstructured data from EHR and PACS needs to be transferred to Amazon S3 to trigger the serverless data processing pipeline through the Lambda functions. You can achieve this data transfer by using AWS Storage Gateway or AWS DataSync, which is out of the scope of this post. The online query API, including the GraphQL schemas and resolvers, was developed in AWS AppSync. The front-end web application was developed using the Amplify React framework, which can be deployed using the Amplify CLI. The detailed AWS CloudFormation templates and sample code are available in the Github repo.

Solution overview

To deploy the solution, you complete the following steps:

  1. Deploy the Amplify React web application for online search.
  2. Deploy the image-embedding container to AWS Fargate.
  3. Deploy the data-processing pipeline and AWS AppSync API.

Deploying the Amplify React web application

The first step creates the Amplify React web application, as shown in the following diagram.

  1. Install and configure the AWS Command Line Interface (AWS CLI).
  2. Install the AWS Amplify CLI.
  3. Clone the code base with stepwise instructions.
  4. Go to your code base folder and initialize the Amplify app using the command amplify init. You must answer a series of questions, like the name of the Amplify app.

After this step, you have the following changes in your local and cloud environments:

  • A new folder named amplify is created in your local environment
  • A file named aws-exports.js is created in local the src folder
  • A new Amplify app is created on the AWS Cloud with the name provided during deployment (for example, medical-image-search)
  • A CloudFormation stack is created on the AWS Cloud with the prefix amplify-<AppName>

You create authentication and storage services for your Amplify app afterwards using the following commands:

amplify add auth
amplify add storage
amplify push

When the CloudFormation nested stacks for authentication and storage are successfully deployed, you can see the new Amazon Cognito user pool as the authentication backend and S3 bucket as the storage backend are created. Save the Amazon Cognito user pool ID and S3 bucket name from the Outputs tab of the corresponding CloudFormation nested stack (you use these later).

The following screenshot shows the location of the user pool ID on the Outputs tab.

The following screenshot shows the location of the bucket name on the Outputs tab.

Deploying the image-embedding container to AWS Fargate

We use the Amazon SageMaker Inference Toolkit to serve the PyTorch inference model, which converts a medical image in DICOM format into a feature vector with the size of 1024. To create a container with all the dependencies, you can either use pre-built deep learning container images or derive a Dockerfile from the Amazon Sagemaker Pytorch inference CPU container, like the one from the GitHub repo, in the container folder. You can build the Docker container and push it to Amazon ECR manually or by running the shell script build_and_push.sh. You use the repository image URI for the Docker container later to deploy the AWS Fargate cluster.

The following screenshot shows the sagemaker-pytorch-inference repository on the Amazon ECR console.

We use Multi Model Server (MMS) to serve the inference endpoint. You need to install MMS with pip locally, use the Model archiver CLI to package model artifacts into a single model archive .mar file, and upload it to an S3 bucket to be served by a containerized inference endpoint. The model inference handler is defined in dicom_featurization_service.py in the MMS folder. If you have a domain-specific pretrained Pytorch model, place the model.pth file in the MMS folder; otherwise, the handler uses a pretrained DenseNET121[4] for image processing. See the following code:

model_file_path = os.path.join(model_dir, "model.pth")
if os.path.isfile(model_file_path): model = torch.load(model_file_path) else: model = models.densenet121(pretrained=True) model = model._modules.get('features') model.add_module("end_relu", nn.ReLU()) model.add_module("end_globpool", nn.AdaptiveAvgPool2d((1, 1))) model.add_module("end_flatten", nn.Flatten())
model = model.to(self.device)
model.eval()

The intermediate results of this CNN-based model is to represent images as feature vectors. In other words, the convolutional layers before the final classification layer is flattened to convert feature layers to a vector representation. Run the following command in the MMS folder to package up the model archive file:

model-archiver -f --model-name dicom_featurization_service --model-path ./ --handler dicom_featurization_service:handle --export-path ./

The preceding code generates a package file named dicom_featurization_service.mar. Create a new S3 bucket and upload the package file to that bucket with public read Access Control List (ACL). See the following code:

aws s3 cp ./dicom_featurization_service.mar s3://<S3bucketname>/ --acl public-read --profile <profilename>

You’re now ready to deploy the image-embedding inference model to the AWS Fargate cluster using the CloudFormation template ecsfargate.yaml in the CloudFormationTemplates folder. You can deploy using the AWS CLI: go to the CloudFormationTemplates folder and copy the following command:

aws cloudformation deploy --capabilities CAPABILITY_IAM --template-file ./ecsfargate.yaml --stack-name <stackname> --parameter-overrides ImageUrl=<imageURI> InferenceModelS3Location=https://<S3bucketname>.s3.amazonaws.com/dicom_featurization_service.mar --profile <profilename>

You need to replace the following placeholders:

  • stackname – A unique name to refer to this CloudFormation stack
  • imageURI – The image URI for the MMS Docker container uploaded in Amazon ECR
  • S3bucketname – The MMS package in the S3 bucket, such as https://<S3bucketname>.s3.amazonaws.com/dicom_featurization_service.mar
  • profilename – Your AWS CLI profile name (default if not named)

Alternatively, you can choose Launch stack for the following Regions:

  • us-east-1

  • us-west-2

After the CloudFormation stack creation is complete, go to the stack Outputs tab on the AWS CloudFormation console and copy the InferenceAPIUrl for later deployment. See the following screenshot.

You can delete this stack after the offline image embedding jobs are finished to save costs, because it’s not used for online queries.

Deploying the data-processing pipeline and AWS AppSync API

You deploy the image and free text data-processing pipeline and AWS AppSync API backend through another CloudFormation template named AppSyncBackend.yaml in the CloudFormationTemplates folder, which creates the AWS resources for this solution. See the following solution architecture.

To deploy this stack using the AWS CLI, go to the CloudFormationTemplates folder and copy the following command:

aws cloudformation deploy --capabilities CAPABILITY_NAMED_IAM --template-file ./AppSyncBackend.yaml --stack-name <stackname> --parameter-overrides AuthorizationUserPool=<CFN_output_auth> PNGBucketName=<CFN_output_storage> InferenceEndpointURL=<inferenceAPIUrl> --profile <profilename>

Replace the following placeholders:

  • stackname – A unique name to refer to this CloudFormation stack
  • AuthorizationUserPool – Amazon Cognito user pool
  • PNGBucketName – Amazon S3 bucket name
  • InferenceEndpointURL – The inference API endpoint
  • Profilename – The AWS CLI profile name (use default if not named)

Alternatively, you can choose Launch stack for the following Regions:

  • us-east-1

  • us-west-2

You can download the Lambda function for medical image processing, CMprocessLambdaFunction.py, and its dependency layer separately if you deploy this stack in AWS Regions other than us-east-1 and us-west-2. Because their file size exceeds the CloudFormation template limit, you need to upload them to your own S3 bucket (either create a new S3 bucket or use the existing one, like the aforementioned S3 bucket for hosting the MMS model package file) and override the LambdaBucket mapping parameter using your own bucket name.

Save the AWS AppySync API URL and AWS Region from the settings on the AWS AppSync console.

Edit the src/aws-exports.js file in your local environment and replace the placeholders with those values:

const awsmobile = { "aws_appsync_graphqlEndpoint": "<AppSync API URL>", "aws_appsync_region": "<AWS AppSync Region>", "aws_appsync_authenticationType": "AMAZON_COGNITO_USER_POOLS"
};

After this stack is successfully deployed, you’re ready to use this solution. If you have in-house EHR and PACS databases, you can set up the AWS Storage Gateway to transfer data to the S3 bucket to trigger the transformation jobs.

Alternatively, you can use the public dataset MIMIC CXR: download the MIMIC CXR dataset from PhysioNet (to access the files, you must be a credentialed user and sign the data use agreement for the project) and upload the DICOM files to the S3 bucket mimic-cxr-dicom- and the free text radiology report to the S3 bucket mimic-cxr-report-. If everything works as expected, you should see the new records created in the DynamoDB table medical-image-metadata and the Amazon ES domain medical-image-search.

You can test the Amplify React web application locally by running the following command:

npm install && npm start

Or you can publish the React web app by deploying it in Amazon S3 with AWS CloudFront distribution, by first entering the following code:

amplify hosting add

Then, enter the following code:

amplify publish

You can see the hosting endpoint for the Amplify React web application after deployment.

Conclusion

We have demonstrated how to deploy, index and search medical images on AWS, which segregates the offline data ingestion and online search query functions. You can use AWS AI services to transform unstructured data, for example the medical images and radiology reports, into structured ones.

By default, the solution uses a general-purpose model trained on ImageNET to extract features from images. However, this default model may not be accurate enough to extract medical image features because there are fundamental differences in appearance, size, and features between medical images in its raw form. Such differences make it hard to train commonly adopted triplet-based learning networks [5], where semantically relevant images or objects can be easily defined or ranked.

To improve search relevancy, we performed an experiment by using the same MIMIC CXR dataset and the derived diagnosis labels to train a weakly supervised disease classification network similar to Wang et. Al [6]. We found this domain-specific pretrained model yielded qualitatively better visual search results. So it’s recommended to bring your own model (BYOM) to this search platform for real-world implementation.

The methods presented here enable you to perform indexing, searching and aggregation against unstructured images in addition to free text. It sets the stage for future work that can combine these features for multimodal medical image search engine. Information retrieval from unstructured corpuses of clinical notes and images is a time-consuming and tedious task. Our solution allows radiologists to become more efficient and help them reduce potential burnout.

To find the latest development to this solution, check out medical image search on GitHub.

Reference:

  1. https://www.radiologybusiness.com/topics/leadership/radiologist-burnout-are-we-done-yet
  2. https://www.mayoclinicproceedings.org/article/S0025-6196(15)00716-8/abstract#secsectitle0010
  3. Johnson, Alistair EW, et al. “MIMIC-CXR, a de-identified publicly available database of chest radiographs with free-text reports.” Scientific Data 6, 2019.
  4. Huang, Gao, et al. “Densely connected convolutional networks.” Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, 2017.
  5. Wang, Jiang, et al. “Learning fine-grained image similarity with deep ranking.” Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, 2014.
  6. Wang, Xiaosong, et al. “Chestx-ray8: Hospital-scale chest x-ray database and benchmarks on weakly-supervised classification and localization of common thorax diseases.” Proceedings of the IEEE Conference on Computer Vision and Pattern Recognition, 2017.

About the Authors

 Gang Fu is a Healthcare Solution Architect at AWS. He holds a PhD in Pharmaceutical Science from the University of Mississippi and has over ten years of technology and biomedical research experience. He is passionate about technology and the impact it can make on healthcare.

Ujjwal Ratan is a Principal Machine Learning Specialist Solution Architect in the Global Healthcare and Lifesciences team at Amazon Web Services. He works on the application of machine learning and deep learning to real world industry problems like medical imaging, unstructured clinical text, genomics, precision medicine, clinical trials and quality of care improvement. He has expertise in scaling machine learning/deep learning algorithms on the AWS cloud for accelerated training and inference. In his free time, he enjoys listening to (and playing) music and taking unplanned road trips with his family.

Erhan Bas is a Senior Applied Scientist in the AWS Rekognition team, currently developing deep learning algorithms for computer vision applications. His expertise is in machine learning and large scale image analysis techniques, especially in biomedical, life sciences and industrial inspection technologies. He enjoys playing video games, drinking coffee, and traveling with his family.

Source: https://aws.amazon.com/blogs/machine-learning/building-a-medical-image-search-platform-on-aws/

AI

Graph Convolutional Networks (GCN)

In this post, we’re gonna take a close look at one of the well-known graph neural networks named Graph Convolutional Network (GCN). First, we’ll get the intuition to see how it works, then we’ll go deeper into the maths behind it. Why Graphs? Many problems are graphs in true nature. In our world, we see many data are graphs, […]

The post Graph Convolutional Networks (GCN) appeared first on TOPBOTS.

Published

on

graph convolutional networks

In this post, we’re gonna take a close look at one of the well-known graph neural networks named Graph Convolutional Network (GCN). First, we’ll get the intuition to see how it works, then we’ll go deeper into the maths behind it.

Why Graphs?

Many problems are graphs in true nature. In our world, we see many data are graphs, such as molecules, social networks, and paper citations networks.

Tasks on Graphs

  • Node classification: Predict a type of a given node
  • Link prediction: Predict whether two nodes are linked
  • Community detection: Identify densely linked clusters of nodes
  • Network similarity: How similar are two (sub)networks

Machine Learning Lifecycle

In the graph, we have node features (the data of nodes) and the structure of the graph (how nodes are connected).

For the former, we can easily get the data from each node. But when it comes to the structure, it is not trivial to extract useful information from it. For example, if 2 nodes are close to one another, should we treat them differently to other pairs? How about high and low degree nodes? In fact, each specific task can consume a lot of time and effort just for Feature Engineering, i.e., to distill the structure into our features.

graph convolutional network
Feature engineering on graphs. (Picture from [1])

It would be much better to somehow get both the node features and the structure as the input, and let the machine to figure out what information is useful by itself.

That’s why we need Graph Representation Learning.

graph convolutional network
We want the graph can learn the “feature engineering” by itself. (Picture from [1])

If this in-depth educational content on convolutional neural networks is useful for you, you can subscribe to our AI research mailing list to be alerted when we release new material. 

Graph Convolutional Networks (GCNs)

Paper: Semi-supervised Classification with Graph Convolutional Networks (2017) [3]

GCN is a type of convolutional neural network that can work directly on graphs and take advantage of their structural information.

it solves the problem of classifying nodes (such as documents) in a graph (such as a citation network), where labels are only available for a small subset of nodes (semi-supervised learning).

graph convolutional network
Example of Semi-supervised learning on Graphs. Some nodes dont have labels (unknown nodes).

Main Ideas

As the name “Convolutional” suggests, the idea was from Images and then brought to Graphs. However, when Images have a fixed structure, Graphs are much more complex.

graph convolutional network
Convolution idea from images to graphs. (Picture from [1])

The general idea of GCN: For each node, we get the feature information from all its neighbors and of course, the feature of itself. Assume we use the average() function. We will do the same for all the nodes. Finally, we feed these average values into a neural network.

In the following figure, we have a simple example with a citation network. Each node represents a research paper, while edges are the citations. We have a pre-process step here. Instead of using the raw papers as features, we convert the papers into vectors (by using NLP embedding, e.g., tf–idf).

Let’s consider the green node. First off, we get all the feature values of its neighbors, including itself, then take the average. The result will be passed through a neural network to return a resulting vector.

graph convolutional network
The main idea of GCN. Consider the green node. First, we take the average of all its neighbors, including itself. After that, the average value is passed through a neural network. Note that, in GCN, we simply use a fully connected layer. In this example, we get 2-dimension vectors as the output (2 nodes at the fully connected layer).

In practice, we can use more sophisticated aggregate functions rather than the average function. We can also stack more layers on top of each other to get a deeper GCN. The output of a layer will be treated as the input for the next layer.

graph convolutional network
Example of 2-layer GCN: The output of the first layer is the input of the second layer. Again, note that the neural network in GCN is simply a fully connected layer (Picture from [2])

Let’s take a closer look at the maths to see how it really works.

Intuition and the Maths behind

First, we need some notations

Let’s consider a graph G as below.

graph convolutional network
From the graph G, we have an adjacency matrix A and a Degree matrix D. We also have feature matrix X.

How can we get all the feature values from neighbors for each node? The solution lies in the multiplication of A and X.

Take a look at the first row of the adjacency matrix, we see that node A has a connection to E. The first row of the resulting matrix is the feature vector of E, which A connects to (Figure below). Similarly, the second row of the resulting matrix is the sum of feature vectors of D and E. By doing this, we can get the sum of all neighbors’ vectors.

graph convolutional network
Calculate the first row of the “sum vector matrix” AX
  • There are still some things that need to improve here.
  1. We miss the feature of the node itself. For example, the first row of the result matrix should contain features of node A too.
  2. Instead of sum() function, we need to take the average, or even better, the weighted average of neighbors’ feature vectors. Why don’t we use the sum() function? The reason is that when using the sum() function, high-degree nodes are likely to have huge v vectors, while low-degree nodes tend to get small aggregate vectors, which may later cause exploding or vanishing gradients (e.g., when using sigmoid). Besides, Neural networks seem to be sensitive to the scale of input data. Thus, we need to normalize these vectors to get rid of the potential issues.

In Problem (1), we can fix by adding an Identity matrix I to A to get a new adjacency matrix Ã.

Pick lambda = 1 (the feature of the node itself is just important as its neighbors), we have Ã = A + I. Note that we can treat lambda as a trainable parameter, but for now, just assign the lambda to 1, and even in the paper, lambda is just simply assigned to 1.

By adding a self-loop to each node, we have the new adjacency matrix

Problem (2)For matrix scaling, we usually multiply the matrix by a diagonal matrix. In this case, we want to take the average of the sum feature, or mathematically, to scale the sum vector matrix ÃX according to the node degrees. The gut feeling tells us that our diagonal matrix used to scale here is something related to the Degree matrix D̃ (Why , not D? Because we’re considering Degree matrix  of new adjacency matrix Ã, not A anymore).

The problem now becomes how we want to scale/normalize the sum vectors? In other words:

How we pass the information from neighbors to a specific node?

We would start with our old friend average. In this case, D̃ inverse (i.e., D̃^{-1}) comes into play. Basically, each element in D̃ inverse is the reciprocal of its corresponding term of the diagonal matrix D.

For example, node A has a degree of 2, so we multiple the sum vectors of node A by 1/2, while node E has a degree of 5, we should multiple the sum vector of E by 1/5, and so on.

Thus, by taking the multiplication of D̃ inverse and X, we can take the average of all neighbors’ feature vectors (including itself).

So far so good. But you may ask How about the weighted average()?. Intuitively, it should be better if we treat high and low degree nodes differently.

We’re just scaling by rows, but ignoring their corresponding columns (dash boxes)
Add a new scaler for columns.

The new scaler gives us the “weighted” average. What are we doing here is to put more weights on the nodes that have low-degree and reduce the impact of high-degree nodes. The idea of this weighted average is that we assume low-degree nodes would have bigger impacts on their neighbors, whereas high-degree nodes generate lower impacts as they scatter their influence at too many neighbors.

graph convolutional network
When aggregating feature at node B, we assign the biggest weight for node B itself (degree of 3), and the lowest weight for node E (degree of 5)
Because we normalize twice, we change “-1” to “-1/2”

For example, we have a multi-classification problem with 10 classes, F will be set to 10. After having the 10-dimension vectors at layer 2, we pass these vectors through a softmax function for the prediction.

The Loss function is simply calculated by the cross-entropy error over all labeled examples, where Y_{l} is the set of node indices that have labels.

The number of layers

The meaning of #layers

The number of layers is the farthest distance that node features can travel. For example, with 1 layer GCN, each node can only get the information from its neighbors. The gathering information process takes place independentlyat the same time for all the nodes.

When stacking another layer on top of the first one, we repeat the gathering info process, but this time, the neighbors already have information about their own neighbors (from the previous step). It makes the number of layers as the maximum number of hops that each node can travel. So, depends on how far we think a node should get information from the networks, we can config a proper number for #layers. But again, in the graph, normally we don’t want to go too far. With 6–7 hops, we almost get the entire graph which makes the aggregation less meaningful.

graph convolutional network
Example: Gathering info process with 2 layers of target node i

How many layers should we stack the GCN?

In the paper, the authors also conducted some experiments with shallow and deep GCNs. From the figure below, we see that the best results are obtained with a 2- or 3-layer model. Besides, with a deep GCN (more than 7 layers), it tends to get bad performances (dashed blue line). One solution is to use the residual connections between hidden layers (purple line).

graph convolutional network
Performance over #layers. Picture from the paper [3]

Take home notes

  • GCNs are used for semi-supervised learning on the graph.
  • GCNs use both node features and the structure for the training
  • The main idea of the GCN is to take the weighted average of all neighbors’ node features (including itself): Lower-degree nodes get larger weights. Then, we pass the resulting feature vectors through a neural network for training.
  • We can stack more layers to make GCNs deeper. Consider residual connections for deep GCNs. Normally, we go for 2 or 3-layer GCN.
  • Maths Note: When seeing a diagonal matrix, think of matrix scaling.
  • A demo for GCN with StellarGraph library here [5]. The library also provides many other algorithms for GNNs.

Note from the authors of the paper: The framework is currently limited to undirected graphs (weighted or unweighted). However, it is possible to handle both directed edges and edge features by representing the original directed graph as an undirected bipartite graph with additional nodes that represent edges in the original graph.

What’s next?

With GCNs, it seems we can make use of both the node features and the structure of the graph. However, what if the edges have different types? Should we treat each relationship differently? How to aggregate neighbors in this case? What are the advanced approaches recently?

In the next post of the graph topic, we will look into some more sophisticated methods.

graph convolutional network
How to deal with different relationships on the edges (brother, friend,….)?

REFERENCES

[1] Excellent slides on Graph Representation Learning by Jure Leskovec (Stanford):  https://drive.google.com/file/d/1By3udbOt10moIcSEgUQ0TR9twQX9Aq0G/view?usp=sharing

[2] Video Graph Convolutional Networks (GCNs) made simple: https://www.youtube.com/watch?v=2KRAOZIULzw

[3] Paper Semi-supervised Classification with Graph Convolutional Networks (2017): https://arxiv.org/pdf/1609.02907.pdf

[4] GCN source code: https://github.com/tkipf/gcn

[5] Demo with StellarGraph library: https://stellargraph.readthedocs.io/en/stable/demos/node-classification/gcn-node-classification.html

This article was originally published on Medium and re-published to TOPBOTS with permission from the author.

Enjoy this article? Sign up for more computer vision updates.

We’ll let you know when we release more technical education.

Continue Reading

AI

Microsoft BOT Framework — Loops

Published

on

Loops is one of the basic programming structure in any programming language. In this article, I would demonstrate Loops within Microsoft BOT framework.

To follow this article clearly, please have a quick read on the basics of the Microsoft BOT framework. I wrote a couple of articles sometime back and the links are below:

Let’s Get Started.

I would be using the example of a TaxiBot described in one of my previous article. The BOT asks some general questions and books a Taxi for the user. In this article, I would be providing an option to the user to choose there preferred cars for the ride. The flow will look like below:

Create a new Dialog Class for Loops

We would need 2 Dialog classes to be able to achieve this task:

  1. SuperTaxiBotDialog.cs: This would be the main dialog class. The waterfall will contains all the steps as defined in the previous article.
  2. ChooseCarDialog.cs: A new dialog class will be created which would allow the user to pick preferred cars. The loop will be defined in this class.

The water fall steps for both the classes could be visualized as:

The complete code base is present on the Github page.

Important Technical Aspects

  • Link between the Dialogs: In the constructor initialization of SuperTaxiBotDialog, add a dialog for ChooseCarDialog by adding the line:
AddDialog(new ChooseCarDialog());

1. 8 Proven Ways to Use Chatbots for Marketing (with Real Examples)

2. How to Use Texthero to Prepare a Text-based Dataset for Your NLP Project

3. 5 Top Tips For Human-Centred Chatbot Design

4. Chatbot Conference Online

  • Call ChooseCarDialog from SuperTaxiBotDialog: SuperTaxiBotDialog calls ChooseCarDialog from the step SetPreferredCars, hence the return statement of the step should be like:
await stepContext.BeginDialogAsync(nameof(ChooseCarDialog), null, cancellationToken);
  • Return the flow back from ChooseCarDialog to SuperTaxiBotDialog: Once the user has selected 2 cars, the flow has to be sent back to SuperTaxiBotDialog from the step LoopCarAsync. This should be achieved by ending the ChooseCarDialog in the step LoopCarAsync.
return await stepContext.EndDialogAsync(carsSelected, cancellationToken);

The complete code base is present on the Github page.

Once the project is executed using BOT Framework Emulator, the output would look like:

Hopefully, this article will help the readers in implementing a loop with Microsoft BOT framework. For questions: Hit me.

Regards

Tarun

Source: https://chatbotslife.com/microsoft-bot-framework-loops-fe415f0e7ca1?source=rss—-a49517e4c30b—4

Continue Reading

AI

The Bleeding Edge of Voice

This fall, a little known event is starting to make waves. As COVID dominates the headlines, an event called “Voice Launch” is pulling…

Published

on

Tapaan Chauhan

This fall, a little known event is starting to make waves. As COVID dominates the headlines, an event called “Voice Launch” is pulling together an impressive roster of start-ups and voice tech companies intending to uncover the next big ideas and start-ups in voice.

While voice tech has been around for a while, as the accuracy of speech recognition improves, it moves into its prime. “As speech recognition moves from 85% to 95% accuracy, who will use a keyboard anymore?” says Voice Launch organizer Eric Sauve. “And that new, more natural way to interact with our devices will usher in a series of technological advances,” he added.

Voice technology is something that has been dreamt of and worked on for decades all over the world. Why? Well, the answer is very straightforward. Voice recognition allows consumers to multitask by merely speaking to their Google Home, Amazon Alexa, Siri, etc. Digital voice recording works by recording a voice sample of a person’s speech and quickly converting it into written texts using machine language and sophisticated algorithms. Voice input is just the more efficient form of computing, says Mary Meeker in her ‘Annual Internet Trends Report.’ As a matter of fact, according to ComScore, 50% of all searches will be done by voice by 2020, and 30% of searches will be done without even a screen, according to Gartner. As voice becomes a part of things we use every day like our cars, phones, etc. it will become the new “norm.”

The event includes a number of inspiration sessions meant to help start-ups and founders pick the best strategies. Companies presenting here include industry leaders like Google and Amazon and less known hyper-growth voice tech companies like Deepgram and Balto and VCs like OMERS Ventures and Techstars.

But the focus of the event is the voice tech start-ups themselves, and this year’s event has some interesting participants. Start-ups will pitch their ideas, and the audience will vote to select the winners. The event is a cross between a standard pitchfest and Britain’s Got Talent.

Source: https://chatbotslife.com/the-bleeding-edge-of-voice-67538bd859a9?source=rss—-a49517e4c30b—4

Continue Reading
AI3 hours ago

Graph Convolutional Networks (GCN)

AI5 hours ago

Microsoft BOT Framework — Loops

AI5 hours ago

The Bleeding Edge of Voice

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

AI20 hours ago

Using Amazon SageMaker inference pipelines with multi-model endpoints

Trending