A Fine Slice Of SQL Server
Tim Brock covers color vision deficiency:
In this blog post and a follow up I’m going to describe why and how we used theming to make diffify.com more accessible to users who suffer from some common visual impairments. Here in Part 1 I’ll cover some of the science and the terminology. Part 2 will look at the actual changes we made.
Click through for a brief discussion of contrast sensitivity and a longer one on color vision deficiency, including why color choice matters.
Comments closedMara Pereira adds target bands to a line chart:
At the time I could not really find an easy way to achieve this… Until error bars came out!
Don’t be fooled though, it’s still a bit tricky to build a line chart like this, however I found it way easier now than before.
So, you must be thinking now “how did you do that?”.
Well, let’s find out!
The end result looks really nice, though it takes a lot of work to get there.
Comments closedAlex Velez lays out the case for tick marks:
Lately, I’ve noticed that more and more graphs don’t include gridlines. If it’s unclear, I believe this to be a positive trend. I, myself, rarely use gridlines, and often remove them when I find them in a graph I’m reviewing. But I don’t stop there.
More often than not, if a chart has gridlines, it will be lacking tick marks along the axis, and possibly an axis line as well.
Read on to see why.
Comments closedMarco Russo and Alberto Ferrari combine two common business requests:
In a previous article, Rolling 12 Months Average in DAX we showed you how to compute a rolling average over a time period. In this new article, we want to take you one step further and show how to compute a moving average over a certain timeframe, that takes into account only the working days. We present two variations of the same solution: one that is optimized, relying on a calculated column, and one that – despite being somewhat slower – works without requiring a calculated column. The latter can be useful in case you need to define the formula in a live-connected report, where calculated columns are not an option.
Because the formula needs to account for working versus non-working days, it cannot rely on standard time intelligence functions. Indeed, DAX time intelligence functions have no knowledge about what it means for a day to be either a working day or a rest day. The NETWORKDAYS DAX function would not be very useful in this case, because it would introduce a slow filter to compute the range of dates that includes the number of working days desired.
Read on to see how they solve this one.
Comments closedRoland Szirmai has fun with field parameters in Power BI:
Meaning that report users can switch between “dimensions” of the data. This is great and already provides a much better UI and UX, but there was no information about the limitations of what “fields” can you add to the parameter table.
To be more specific, I couldn’t find any limitation about adding measures (Explicit Measures) to the Field Parameter.
I think you can see where my mind wandered after that…
Read on for the result of Roland’s wanderings.
Comments closedRick Pack updates a package to support a project:
I am happy to announce a contribution to the biscale package that makes printing shorter labels using SI prefixes (e.g., 1,000,003 => 1M and 1,324 => 1.3k) far easier. This makes printing the legend in an attractive easier, although you can tell by the picture above that I still struggle with optimal uses of the cowplot package’s draw_plot(). I would love for the legend and map to be centered under the title.
The new si_levels argument for bi_class_breaks() takes a logical value of TRUE or FALSE for either a single or two-unit vector, with a single unit vector causing the specified value to be applied to both the X and Y variables. This matches Prener’s convenient functionality for the number of digits function dig_lab, as he requested in the Github Issue I created for this addition. Note that si_levels rounds the input number, if appropriate, based on the digits indicated by dig_lab, which defaults to 3.
Click through to get access to the update, as well as to see some of the visuals Rick put together with it.
1 CommentDerek Jones digs into an image:
A month or so ago, I found a graph showing a percentage of PCs having a given range of memory installed, between March 2000 and April 2020, on a TechTalk page of PC Matic; it had the form of a stacked density plot. This kind of installed memory data is rare, how could I get the underlying values (a previous post covers extracting data from a heatmap)?
Read on for an interesting attempt at reverse-engineering the original numbers used to create an image. H/T R-Bloggers.
Comments closedMeagan Longoria has a checklist:
For more formal enterprise Power BI development, many people have a checklist to ensure data acquisition and data modeling quality and performance. Fewer people have a checklist for their data visualization. I’d like to offer some ideas for quality checks on the visual design of your Power BI report. I’ll update this list as I get feedback or new ideas.
Read on for the list, as it’s a good one. For the most part, these also apply to visuals created in other tools.
Comments closedMichal Bar has a few updates to the Azure Data Explorer web tool:
We are focused on continuously improving the results exploration experience in ADX web UI, to make it easy and intuitive. Our goal is to provide an easy-to-use UI so that you will not be required to re-write KQL queries in order to perform light-weight data exploration.
Click through to see how you can search and filter within the results pane (something I’d like to see in other Microsoft data platform tools like SSMS), create series panels on charts from KQL, and more.
Comments closedAlex Velez takes us through stacked bar charts:
A few years ago, we posted a question on this blog that is as relevant today as it was years ago: “Is there a good use case for a stacked bar chart?”
Stacked bars are everywhere; you’ve likely seen them in a recent report, a dashboard, or in the media. Despite their prevalence, they are commonly both misused and misunderstood. In this guide, we’ll aim to rectify these mishaps by sharing examples, clarifying when you should (and shouldn’t) use a stacked bar chart, and discussing best practices for stacking bars.
Read on for plenty of good advice around when to use stacked (either regular stacked bar charts or 100% stacked), horizontal vs vertical, and how to format them when it does make sense to drop one in.
Comments closed