Matrix Operations in R

Kristian Larsen shows off some linear algebra concepts in R:

In this article, you learn how to do linear algebra in R. In particular, I will discuss how to create a matrix in R, Element-wise operations in R, Basic Matrix Operations in R, How to Combine Matrices in R, Creating Means and Sums in R and Advanced Matrix Operations in R.

The post is so chock-full of examples, the only block of multi-line text is the description.

Creating Models with ML.NET

I have a series on ML.NET; in this post, I look at building a model:

Okay, now that I have classes, I need to put in that lambda. I guess the lambda could change to qb => qb.Quarterback == "Josh Allen" ? "Josh Allen" : "Nate Barkerson" and that’d work except for one itsy-bitsy thing: if I do it the easy way, I can’t actually save and reload my model. Which makes it worthless for pretty much any real-world scenario.

So no easy lambda-based solution for us. Instead, we need a delegate. 

The experience so far has been a bit frustrating compared to doing similar work in R, but they’re actively working on the library, so I’m hopeful that there will be improvements. In the meantime, I’ve landed on the idea of doing all data cleanup work outside of ML.NET and just use the simplest transformations.

Cosmos DB Role-Based Access Control

Hasan Savran takes us through role-based access control in Cosmos DB:

Role-based access control (RBAC) is available for Azure CosmosDB. By using RBAC, you can manage who has access to CosmosDB resources. You need to have a profile in Azure Active Directory to assign RBAC roles to users, groups or other targets. There are 4 built-in roles you can use. Microsoft announced the CosmosDB Operator
 role recently.

Click through for that list.

Using CHOOSE() in SQL Server

Bert Wagner explains the CHOOSE() function:

While I know I don’t utilize most of the features available in SQL Server, I like to think I’m at least aware that those features exist.

This week I found a blind-spot in my assumption however. Even though it shipped in SQL Server 2012, the SQL Server CHOOSE function is a feature that I think I’m seeing for the first time this past week.

CHOOSE() and IIF() were functions ported over to make it easier for Access and Excel users to write code. I tend to avoid them because there are typically better idiomatic constructs (like CASE) in SQL Server.

Finding Help for M Functions

Erik Svensen shows how you can find help for M functions without leaving the Power Query editor:

One of the things you should know when working with PowerQuery is that you can get a list of all functions in M by adding a blank query and use the #shared expression to get all the functions.

Read on for an example and an even easier way to get information for a single function.

Avoiding OR Clauses in Joins

Erik Darling wants you to embrace the power of AND:

I had to write some hand-off training about query tuning when I was starting a new job.

As part of the training, I had to explain why writing “complicated logic” could lead to poor plan choices.

So I did what anyone would do: I found a picture of a pirate, named him Captain Or, and told the story of how he got Oared to death for giving confusing ORders.

Click through for a troublesome query and a few ways of rewriting it to be less troublesome. My goto is typically to rewrite as two statements with a UNION ALL between them if I can.

Importing Performance Analyzer Results into DAX Studio

Marco Russo shows how you can take data from Performance Analyzer and load it into DAX Studio:

DAX Studio helps you navigate through the performance metrics; it improves the productivity in executing one or more of the collected queries, reducing the number of copy/paste operations required. In order to use the DAX Studio feature, first you must export the data collected by Performance Analyzer in Power BI Desktop.

Click through to see how it’s done.

Building an ARM Template for Azure Data Factory

Kevin Feasel


Cloud, ETL

Andy Leondard takes the first steps to building an Azure Data Factory pipeline using Azure Resource Manager Templates:

Azure Resource Manager, or ARM, “allows you to provision your applications using a declarative template.” So says the Azure Quickstart Templates page. ARM templates are JSON and allow administrators to import and export Azure resources using varying management patterns. I really like ARM templates for implementing infrastructure as code in Azure. In this post I show a very simple example of how to use ARM templates to export and then import a basic ADF (Azure Data Factory) pipeline.

The sample code doesn’t do that much by itself, but it does open up a new world of automation.


June 2019
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