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Category: Dates and Numbers

Creating a Time Dimension in Power BI via DAX

Published 2023-08-14 by Kevin Feasel

Angela Henry gets a watch:

There are some instances when you want to analyze data over time, not just dates. Most of us are familiar with having to create date tables and use them in analysis, but having to analyze data over time is not as common. Let’s say you run a taxi company and you want to determine when your busiest times of day are. This would come in handy for scheduling drivers. You need more drivers during busy times because no one wants to wait for a taxi!

Read on to see one way to create the table in Power BI.

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Creating a Simple Date Dimension in Databricks

Published 2023-08-10 by Kevin Feasel

Chen Hirsh builds a table:

A date dimension is extremely useful and is required by most BI applications. This kind of dimension has a key of time level (day, month, etc.), and attributes that describe it such as year, month, etc. In your BI model, you join this dimension to facts on their date fields, to aggregate from day level to week, month, and year.

In this post, I will demonstrate how to create a date dimension on Azure Databricks using Python. A link to the complete Databricks notebook is at the end of the post.

Check out the code, as well as explanation, in that post.

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Comparing Non-Standard Time Periods in Power BI

Published 2023-08-01 by Kevin Feasel

Marco Russo and Alberto Ferrari are back in school:

A requirement to apply the following technique is that every day can belong to a term or not, but there are no overlaps between terms. Indeed, if we had overlapping periods, we should create a different solution based on the Comparing different time periods pattern. In the case of school terms, we consider the case of three terms per year, where the first term starts in September of one year, and the last term ends in July of the following year. Therefore, the academic year is identified by two consecutive numbers, such as 2016-2017 (often shortened to 2016-17).

The business requirement is to compare one term with the previous term (within the same academic year or the previous one when we compare the first term of a year) and one term with the same term in the previous year. The goal is to obtain a result similar to the following one.

This turns out to be a little bit of a challenge, though Marco and Alberto have the solution for us.

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Filling Gaps in T-SQL

Published 2023-05-30 by Kevin Feasel

Itzik Ben-Gan has a new challenge:

The task involves developing a stored procedure called GetBalances that accepts a parameter called @accountid representing an account ID. The stored procedure should return a result set with all existing dates and balances for the input account, but also gap-filled with the dates of the missing workdays between the existing minimum and maximum dates for the account, along with the last known balance up to that point. The result should be ordered by the date.

My first thought was last observation carried forward, which is now available in SQL Server 2022 (Itzik’s solution 2). I kind of thought of solution 3, though did not think through the mechanics of how it’d work and so I get no credit there.

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Common Date and Time Operations in R

Published 2023-05-18 by Kevin Feasel

Steven Sanderson works with dates:

Dates and times are essential components in many programming tasks, and R provides various functions and packages to handle them effectively. In this post, we’ll explore some common operations using both the base R functions and the lubridate package, comparing their simplicity and ease of understanding.

I personally prefer the lubridate style of date operation, but it’s nice to have options.

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Elapsed Timers in Powershell

Published 2023-05-16 by Kevin Feasel

Robert Cain keeps track of time:

I’m still working on my documentation for my ArcaneBooks project, but wanted to have something for you to read this week, so decided to show you how to create an elapsed timer in PowerShell.

It can be helpful to determine how long a process runs in PowerShell. You can use it to determine what parts of code may need to be optimized, or gather metrics around your functions.

This is the same stopwatch operation which is available in .NET generally, so if you’re using C# or F#, it’s the same basic process.

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Dates and Times in R

Published 2023-05-16 by Kevin Feasel

Steven Sanderson talks dates and times. First up is an overview of how built-in date functionality works in R:

In this post, we will cover the basics of handling dates and times in R using the as.Date, as.POSIXct, and as.POSIXlt functions. We will use the example code below to explain each line in simple terms. Let’s get started!

The second post covers the Date type, as well as date plus time:

In the first part of our code, we use the as.Date() function to find the next Mother’s Day. Since we don’t need to consider specific times, we can simply use the Date class, which simplifies the process. We create a vector with two elements: startMothersDay and endMothersDay, both set to “2024-05-14”. This represents the range of Mother’s Day for the year 2024. Finally, we store the result in the variable NextMothersDay and print it to the console. Voilà! We have the next Mother’s Day date.

Note that this isn’t a post about date calculation, such as finding the Nth Sunday in the month of May

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