Author Archives: Neil Rubens

About Neil Rubens

see http://ActiveIntelligence.org

DynamoDB: An AttributeValue may not contain an empty string (Exception)

Problem com.amazonaws.AmazonServiceException: One or more parameter values were invalid: An AttributeValue may not contain an empty string (Service: AmazonDynamoDBv2; Solution This cryptic message basically says that dynamodb is not able to save fields with empty strings (or null) (a rather … Continue reading

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org.codehaus.mojo:nbm-maven-plugin: Module has friend dependency on but is not listed as a friend

Problem [ERROR] Failed to execute goal org.codehaus.mojo:nbm-maven-plugin:3.14:manifest (default-manifest) on project move: Module has friend dependency on org.netbeans.bootstrap but is not listed as a friend. -> [Help 1] Solution Add scope: provided; e.g.: <dependency> <groupId>org.netbeans.modules</groupId> <artifactId>org-netbeans-bootstrap</artifactId> <version>RELEASE81</version> <scope>provided</scope> </dependency>   keywords: … Continue reading

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Upgrading Gephi 0.8 to 0.9

Gephi’s API had a rather significant API changes; here are some tips for the upgrades. This nifty repo can get you started quickly: https://github.com/gephi/gephi-plugins This repo provides good examples of API usage: https://github.com/gephi/gephi-toolkit-demos API Changes AttributeColumn subGraphFitnessCol = model.getNodeTable().getColumn(FLD_SUBGRAPH_FITNESS, AttributeType.DOUBLE); -> Column … Continue reading

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Machine Learning Book Recommendations

I am often asked to recommend books on machine learning (ML).  Here is a WIP list of my recommendations: http://www.amazon.com/gp/registry/wishlist/1TLVK1WKJF47S/  

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Using AWS Lambda Alias with API Gateway

Using AWS lambda with specific alias through API Gateway; as described here with a command like: aws lambda add-permission –function-name arn:aws:lambda:us-east-1:xxxxxx:function:getData –source-arn arn:aws:execute-api:us-east-1:xxxxxx:t463p6g84d/*/POST/data –principal apigateway.amazonaws.com –statement-id  –action lambda:InvokeFunction Resulted in an error aws: error: argument operation: Invalid choice, valid choices are: … Continue reading

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AWS Lambda invoking from code

You can invoke a lambda from your code (details); you’d probably want to use the AWSLambdaAsyncClient. CAUTION: you have to be very careful not to make re-cursive calls (unless that is your intention); otherwise you might get into an infinite loop. … Continue reading

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DynamoDB: batch delete

Excerpt from my program; adapt as needed:   val client = new AmazonDynamoDBClient() val dynamo = new DynamoDB(client) val scanRequest = new ScanRequest() .withTableName(LocationRecord.TABLE_NAME) val items = client.scan(scanRequest).getItems items.grouped(25).foreach(group => { // DynamoDB: Member must have length less than or … Continue reading

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does not map a @DynamoDBHashKey attribute; ensure a public, zero-parameter get method/field is annotated

Problem: “` Class does not map a @DynamoDBHashKey attribute; ensure a public, zero-parameter get method/field is annotated com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingException: Class does not map a @DynamoDBHashKey attribute; ensure a public, zero-parameter get method/field is annotated at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMappingsRegistry$Mappings.getHashKey(DynamoDBMappingsRegistry.java:245) at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.needAutoGenerateAssignableKey(DynamoDBMapper.java:682) at com.amazonaws.services.dynamodbv2.datamodeling.DynamoDBMapper.save(DynamoDBMapper.java:708) at … Continue reading

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AWS Lambda: extending execution time limit

Currently AWS Lambda limits execution time to 5 min.  However, in quite a few cases it is possible to overcome this limitation by simply re-invoking your function in an iterative manner.  Here are brief details. You can keep a tab … Continue reading

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Using Google Scholar for managing your publications bibliography

Google Scholar (GS) is a very nifty tool.   However some of the features are not intuitive. Export Your Publications from your profile You can do that by clicking the checkbox (next to Title) in the header (export icon will … Continue reading

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