M

Automatically create function record for Expression.Evaluate in Power BI and Power Query

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Some time ago I wrote a blogpost on how to create a function library in Power BI or Power Query (http://www.thebiccountant.com/2017/08/27/how-to-create-and-use-r-function-library-in-power-bi/). There I also presented a way to pull that function code automatically from GitHub.

Problem

In that code I used the function Expression.Evaluate to execute the imported text and create functions from it. The inbuilt functions that I’ve used in that code have to be passed as an environment record at the end of the expression. I’ve used #shared for it, as this returns a record with all native M-functions and is quick and easy to write (if environments are new to you, check out this series: https://ssbi-blog.de/the-environment-concept-in-m-for-power-query-and-power-bi-desktop/ ). But as it turns out, this can cause problems when publishing to the service unfortunately (https://social.technet.microsoft.com/Forums/ie/en-US/208b9365-91e9-4802-b737-de00bf027e2a/alternative-calling-function-with-text-string?forum=powerquery – please leave a vote if you would like to use #shared in the service as well).

Solution

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Permutations table in Power BI or Power Query in Excel

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Today my husband came with a special task to me: He had to re-wire an old instrument on board of our sailing boat and “lost” the original matching instructions. There were 4 cables to go into 4 different holes, which left him with 24 possible combinations. So he needed a permutations table with all possible combinations that he could print out and tick each combination that he would try subsequently:

To be honest, he was quicker in creating the permutations table manually in Excel than me in Power Query, as it took me a while to develop an easy enough algorithm. But the technique I came out with at the end is so typical “Power Query”-ish, that I’m going to share it here:

The Video

The Function

Here comes the function code:

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Migrate a Power Query or Power BI file to a local SSAS instance

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Edit: This feature has been deprecated since 1st March 2019 unfortunately: https://azure.microsoft.com/en-us/updates/azure-analysis-services-web-designer-to-be-discontinued/ – Microsoft is working on replacement of the functionality to move pbix-files to SSAS-instances, but no solution yet. In Visual Studio there is a wizard to migrate an Excel Power Pivot model to a SSAS model. But this will not bring over the M-queries … Read more

Web Scraping 2: Scrape multiple pages at once and refresh in Power BI service

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In the first post of this series I’ve explained how to simultaneously load and combine multiple (similar structured) tables from ONE PAGE. This post handles the other direction, how to combine tables from DIFFERENT PAGES into one (or to scrape multiple webpages at once). Overview Theoretically, this is quite a simple process: Create a query that fetches and transforms … Read more

A generic SWITCH-function for the query editor in Power BI and Power Query

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Although you can easily replicate the DAX SWITCH-function via list-, table- or record functions in M, I thought it would be convenient for many newbies to have a comfortable M-SWITCH-function that uses (almost) the same syntax than its DAX-equivalent:

SWITCH (
[Month],
    1, “January”,
    2, “February”,
    3, “March”,
    4, “April”,
    5, “May”,
    6, “June”,
    7, “July”,
    8, “August”,
    9, “September”,
    10, “October”,
    11, “November”,
    12, “December”,
    “Unknown month number”
)
DAX Formatter by SQLBI

The DAX-SWITCH-function will retrieve the content of its first argument (expression) ([Month]) and check it against he first parameters of the following pairs (value). If there is a match, the second parameter of the pairs (result, here: month name) is returned and if there is no match, “Unknown month number” will be returned.

How it works

The syntax for the M-function looks like so:

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Web Scraping 1: Combine multiple tables from one page in Power BI and Power Query

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This is a step-by-step description of how to combine multiple tables from one webpage into one table with categories as output. You can also apply this technique to combine tables from other sources as well (like from folder method for example or multiple different webpages (see this article)).

Sometimes the page you want to scrape has multiple tables like here:

0 – Combine multiple tables into one: Input

And you want to combine them into 1 with a Category-column like so:

1 – Combine multiple tables into one: Result

Overview

I will present 2 methods here:

  1. Append-method: This is the obvious one and is fast for just a few tables.
  2. Add-Column-method: A bit more complicated but will be faster for a large number of tables and is also suitable for a dynamic number of tables.

You will also find 2 options at the end of this article:

  1. Use custom functions for multi-step table transformations
  2. Use dynamic filters to select the desired tables

 

Append method

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