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Day: May 21, 2018

Using xplain To Interpret Model Results

Published 2018-05-21 by Kevin Feasel

Joachim Zuckarelli walks us through the xplain package in R:

The above XML produces the following output (don’t worry too much about the call of xplain(), we will discuss later on in more detail how to work with the xplain() function):

library(car)
library(xplain)
xplain(call="lm(education ~ young + income + urban, data=Anscombe)",
xml="http://www.zuckarelli.de/xplain/example_lm_foreach.xml")

##
## Call:
## lm(formula = education ~ young + income + urban, data = Anscombe)
##
## Coefficients:
## (Intercept) young income urban
## -286.83876 0.81734 0.08065 -0.10581
##
##
## Interpreting the coefficients
## —————————–
## Your coefficient ‘(Intercept)’ is smaller than zero.
##
## Your coefficient ‘young’ is larger than zero. This means that the
## value of your dependent variable ‘education’ changes by 0.82 for
## any increase of 1 in your independent variable ‘young’.
##
## Your coefficient ‘income’ is larger than zero. This means that the
## value of your dependent variable ‘education’ changes by 0.081 for
## any increase of 1 in your independent variable ‘income’.
##
## Your coefficient ‘urban’ is smaller than zero. This means that the
## value of your dependent variable ‘education’ changes by -0.11 for
## any increase of 1 in your independent variable ‘urban’.

I’ll be interested in looking at this in more detail, though my first glance indication is that it’ll be useful mostly in large shops with different teams creating and using models.

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Sentiment Analysis Of Hotel California

Published 2018-05-21 by Kevin Feasel

Sara Locatelli analyzes the lyrics to Hotel California using tidytext:

Sentiment analysis is a method of natural language processing that involves classifying words in a document based on whether a word is positive or negative, or whether it is related to a set of basic human emotions; the exact results differ based on the sentiment analysis method selected. The tidytext R package has 4 different sentiment analysis methods:

  • “AFINN” for Finn Årup Nielsen – which classifies words from -5 to +5 in terms of negative or positive valence
  • “bing” for Bing Liu and colleagues – which classifies words as either positive or negative
  • “loughran” for Loughran-McDonald – mostly for financial and nonfiction works, which classifies as positive or negative, as well as topics of uncertainty, litigious, modal, and constraining
  • “nrc” for the NRC lexicon – which classifies words into eight basic emotions (anger, fear, anticipation, trust, surprise, sadness, joy, and disgust) as well as positive or negative sentiment

Sentiment analysis works on unigrams – single words – but you can aggregate across multiple words to look at sentiment across a text.

To demonstrate sentiment analysis, I’ll use one of my favorite songs: “Hotel California” by the Eagles.

Read the whole thing, though you can’t check out afterward.

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Digging Into The SQL Compute Context With R Services

Published 2018-05-21 by Kevin Feasel

Niels Berglund dives into how the SQL Compute Context works with R Services:

In the code above we use the RxInSqlServer() function to indicate we want to execute in a SQL context. The connectionString property defines where we execute, and the numTasks property sets the number of tasks (processes) to run for each computation, in Code Snippet 4 it is set to 1 which from a processing perspective should match what we do in Code Snippet 3. Before we execute the code in Code Snippet 4 we do what we did before we ran the code in Code Snippet 3:

  • Run Process Explorer as admin.
  • Navigate to the devenv.exe process in Process Explorer.
  • In addition, also look at the Launchpad.exe process in Process Explorer.

When we execute we see that the BxlServer.exe processes under the Microsoft.R.Host.exe processes are idling, but when we look at the Launchpad.exe process we see this:

This is a bit deep but interesting reading.

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Creating Choropleths With ggcounty

Published 2018-05-21 by Kevin Feasel

Sebastian Sauer has a quick example of using ggcounty to plot data on a map of US counties:

This posts shows how easy it can be to build an visually pleasing plot. We will use hrbrmster’s ggcounty, which is an R package at this Github repo. Graphics engine is as mostly in my plots, Hadley Wickhams ggplot. All build on R. Standing on shoulders…

Disclaimer: This example heavily draws on hrbrmster example on this page. All credit is due to Rudy, and those on whose work he built up on.

In just a few lines of code, you can have a pretty nice map.

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Getting Month Names Given Numbers In DAX

Published 2018-05-21 by Kevin Feasel

Philip Seamark shows how to convert month numbers into names in Power BI:

The most common solution I see offered is along the lines of a SWITCH statement that lists 12 conditions (one for each month).   This works, but can also be done using existing functions.

While DAX lacks a dedicated function to convert a number to a text version, such as DATENAME in T-SQL, we can get there in two functions using DATEVALUE wrapped in a FORMAT.

To demonstrate, I will create a simple table with 13 values (1 through 13) using the following calculated table.

This creates a single column table with 13 rows.

Read on for the rest of the story.

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Overlaying Visuals In Power BI

Published 2018-05-21 by Kevin Feasel

Annie Xu gives us two methods for being able to jump between two visuals in the same space:

Disconnected Table method:

This method is more towards PowerBI modelers. Basically, the idea is to have a Field in a independent table (no relationship to other tables) as Slicer with your measure choice and then create a measure using SELECTEDVALUE function to have the measure dynamically switch referring measures based on the choice made on the slicer.

Click through for both methods.

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JSON Data In SSIS

Published 2018-05-21 by Kevin Feasel

Stacia Varga shows a few methods for handling JSON data in SQL Server Integration Services:

And then I had to write about it in my book Introducing Microsoft SQL Server 2016 (which is free to download) when JSON support was added to SQL Server 2016. But I still didn’t have clients using JSON. It was interesting to me that I could use SQL Server to work with JSON data, but it was still theoretical to me rather than practical.

Therefore, I never thought much about how I would handle it in SQL Server Integration Services (SSIS). I just didn’t have a reason.

Until now. This seems to be the year that I am bumping into JSON left and right. It’s everywhere!

Read on for those methods as well as Stacia’s recommendation.

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Exporting Table Details With Powershell

Published 2018-05-21 by Kevin Feasel

Andy Levy helps an end user understand a database schema:

This week I had a user come to me asking about how fields were defined on a few tables he was using in writing some reports. Long story short, he’s been tasked with writing some new reports and updating existing ones, but he doesn’t have visibility to the database itself so he’s left with the “ok, let’s try this” approach and then reading error messages to debug when things go sideways. Very tedious.

I asked him for a list of the tables he was most interested in, and while he worked on that I set to work on (of course) a quick & dirty PowerShell script to collect the data he needed – field names, types, and whether they’re nullable.

Ideally these analysts would have data model documentation, but it’s not an ideal world.

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