Designing For Usability In Power BI

Avi Singh walks through a usability scenario in Power Pivot and Power BI:

Here is how we can go about combining the Products and the newly created SubCategory table for a more usable and elegant solution. I have highlighted the key steps, you can examine the solution file to go step by step in the Power BI Query.
Note: Don’t be scared of the M code, 99% of these steps were generated using the Query ribbon – I have included those screenshots as well.

When developing BI models, it’s important to keep things as simple as possible.  Your desired end user likely does not have the necessary skill level to wade through normalized table designs, so make it easy for them to get their jobs done.

Custom Visualizations

Ginger Grant is good with using custom visualizations in Power BI:

Now since Power BI Custom Visualizations are not provided by Microsoft, they feel compelled to give you a warning message letting users know this. Here is the message box you get in Power BI Desktop when using a custom visualization. Notice that I clicked on the check box next to the text Don’t show this dialog again. As Words mean things, checking this box means the warning message never appears again. When you import the visualization into Power BI, no warning messages. Now I can use and propose custom visualizations to clients because they really are neat, and now they contain no warnings. Thanks so much to the Power BI Product team for fixing this major issue.

This is good news.

“Let” Expressions In M

Chris Webb explains “let” expressions  in M:

In the M language a let expression consists of two sections. After the let comes a list of variables, each of which has a name and an expression associated with it. In the previous example there are three variables: step1, step2 and step3. Variables can refer to other variables; here, step3 refers to both step1 and step2. Variables can be used to store values of any type: numbers, text, dates, or even more complex types like records, lists or tables; here, all three variables return numbers. The Query Editor is usually clever enough to display these variables as steps in your query and so displays then in the Applied Steps pane on the right-hand side of the screen

It’s a look at one of the fundamentals of an interesting language.

DAX Time Zones With Power BI

Reza Rad shows a few ways to deal with date/time issues related to Power BI being in the cloud:

Power BI is a cloud service, and that means Power BI files are hosted somewhere. Some DAX functions such as Date/Time functions work on system date/time on the server their file is hosted on. So If you use DAX functions such as TODAY() or NOW() you will not get your local date/time, You will fetch server’s date/time. In this blog post I’ll explain methods of solving this issue, so you could use Power BI to resolve your specific time zone’s date and time. If you want to learn more about Power BI read Power BI online book; Power BI from Rookie to Rock Star.

This is your daily reminder that “the cloud” is just somebody else’s machine.

Finishing The Event Scheduler

Reza Rad has part 3 of his event date and time scheduler up:

This table has three columns: Date, Time, and Duration. I separated the date and time for simplicity of this example. Date to be formatted as YYYYMMDD, and Time as HHMM, and duration as an integer value illustrating hours.

Configuration above means the event starts at 9th of May 2016, at 1:00 pm New Zealand time (this is what my local time is), with duration of 3 hours. I named this table as InputData.

This wraps up his series on Power Query for non-BI developers.

Creating M Functions From Parameterized Queries

Chris Webb shows how to take a parameterized query in Power BI and create an M function from it:

All of these examples involve writing M code manually. The big change in the latest version of Power BI Desktop is that you can do the same thing using just the UI.

Let’s take the classic example of combining data from multiple Excel workbooks and update it to show how things work now.

Say you have a folder containing three Excel workbooks containing sales data for January, February and March and you want to load data from all three into a single table into Power BI. The first thing to do is to create a new parameter in Power BI Desktop that returns the filename, including path, of one of the Excel files. Call it ExcelFilePath and configure it as shown here:

This is pretty cool.

Power Query For The Rest Of Us

Reza Rad talks about using Power Query in a distinctly non-BI fashion:

As an introduction to this series, I want to take you to the path that leads me to use Power Query here. You might be aware that I am teaching Power BI courses, and most of my courses are online and Live. This means that courses are not recorded videos, it is me on the other side of the line with full interactive audio and video experience with students with Go2Meeting application. Students connecting to me from other places in the world. So I do need an event date/time scheduler that I can announce date and time of the event in different time zones.

Fortunately there is a very good website that helps to find a date/time in different time zones. In this website I can set my input parameters as the date/time of my event locally (in my city), and name of the event, and duration.

In Part 2, Reza shows grouping and concatenation:

Now that I have values in multiple columns I can concatenate them all into one string with Table.ToList function which converts a table to List. This function can concatenate all columns of table into one column (because List is a single columned data structure).

The actual concatenation happens by Combiner function; Combiner.CombineTextByDelimiter(“, “) which concatenate values with a delimiter which I set to be comma. So here is the expression for my new custom column:

Part 3 is forthcoming and should wrap up this series.

Power BI Desktop Or Power Pivot

Bill Anton discusses when to use Power BI Desktop and when to use Power Pivot:

In the whitepaper, Strategic Prototyping is defined as the process of leveraging Power BI to explicitly seek out feedback from users during a requirements discovery session. The general idea is to use a prototyping tool to quickly slap together a model and mock up some reports while working closely with 1 or more business users. This helps ensure all reporting capabilities are flushed out and accounted for. After several iterations, the Power BI model becomes the blueprint upon which an enterprise solution can be based.

Prior to the emergence of Power BI, the tool of choice for strategic prototyping (at least in Microsoft shops) was Power Pivot. And even though the reporting side of Power Pivot is nowhere near as sexy as Power BI, there is one really awesome feature that does not (yet?) exist with Power BI… and that’s the “Import from PowerPivot” option in visual studio…

Bill does a good job of explaining the alternatives and, importantly, explaining that whichever you pick, there will be follow-up work.

Power BI Takeover

Devin Knight has a Q&A on Power BI:

Q: what is the difference between the Query editor and Data Modeler? What can and can’t do in each case ?

To summarize the Query Editor is mainly for Data Extraction actions.  So providing source information, applying rules to the incoming data, etc… The Data Modeling areas are focused on creating relationships between tables you’ve important and creating calculations you might need in your report.  This of this as the last step to prepare you data for reports.

Check out Devin’s webinar as well.  It’s a lot longer than a coffee break, but worth your time.

Custom Power BI Visuals

Rob Farley looks into custom Power BI visuals:

I hadn’t explored much in the way of custom visuals in Power BI until a while back, even though I was very much aware of the competition that was held in September. It had been on my list to explore some of what was possible. And this month, the T-SQL Tuesday topic (hosted by Wendy Pastrick@wendy_dance) was to learn something new and to blog about it. So it seemed a good idea to learn how to make my own custom visualisation!

Now, creativity isn’t exactly my thing. I find it really hard to write songs, for example. I know how to do it – but I quickly become self-critical and get stuck. Writing is easier, because it feels less ‘creative’, and appeals more to the teacher / preacher in me (and I know that takes creativity, especially if you’ve ever seen me present, but it’s different). So sitting down and coming up with a new way of visualising data wasn’t something I was going to do.

For more info, check out more info on creating visuals and using R to visualize data in Power BI.

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