How to Use a List as Filter Argument in Power Query

Power Query is a unique feature in Power BI for data cleaning and transformation, offering several filtering options, which include using a list as a filter argument especially when filtering data based on multiple values.

By using a list as a filter, you can swiftly filter and modify your data, allowing you to gain deeper insights in order to make more data-driven decisions.

In this article, I will explore how to use a list as a filter argument in Power Query, and other details you need to know.

So, let’s dive right in!

Overview of Filter Arguments in Power Query

Typically, filter arguments in Power Query let users retrieve specific rows of data based on certain conditions. For example, you can use simple conditions like “equals” or “greater than” to apply filters.

However, Power Query takes it further by introducing “using a list as a filter argument.” With this, users can select multiple values to filter their data, e.g., a whole range of values, rather than just a single value.

Now, let me walk you through the steps to use a list as a filter argument in Power Query. Let’s go!

Requirements

  • Power BI Desktop: Download Power BI Desktop on the official Microsoft website and make sure you have it installed on your computer.
  • Import your Data: You must also import the data you want to work with into Power BI. Click on “Get Data” in the Home tab of your Power BI Desktop.

A Guide to Using a List as a Filter Argument in Power Query

1. Open Power Query Editor

Now that you have successfully imported your data into Power BI, the next thing to do is to open up Power Query Editor.

To do this, click on the “Transform data” button in the Home tab, then click on “Transform data.”

how to use a list as filter argument in power query - monocroft

Below is what my Power Query Editor’s interface looks like after importing the dataset:

how to use a list as filter argument in power query - monocroft

2. Create a List of Filter Values

To use a list as a filter argument, you need to create a list of values you want to filter, which you can either create manually or load from another source. Here is how to create it manually.

  • Open your Power Query Editor, go to the “Home” tab, and click on “Advanced Editor” to access the Power Query script editor.

In the Advanced Editor, use the List function to create your list. For example, with my data, I can create a list of movie genres:

let
    Source = Excel.Workbook(File.Contents("C:\Users\USER\Downloads\IMDB-Movie-Data.xlsx"), null, true),
    #"IMDB-Movie-Data_Sheet" = Source{[Item="IMDB-Movie-Data",Kind="Sheet"]}[Data],
    #"Promoted Headers" = Table.PromoteHeaders(#"IMDB-Movie-Data_Sheet", [PromoteAllScalars=true]),
    #"Changed Type" = Table.TransformColumnTypes(#"Promoted Headers",{
        {"Rank", Int64.Type}, 
        {"Title", type any}, 
        {"Genre", type text}, 
        {"Description", type text}, 
        {"Director", type text}, 
        {"Actors", type text}, 
        {"Year", Int64.Type}, 
        {"Runtime (Minutes)", Int64.Type}, 
        {"Rating", type number}, 
        {"Votes", Int64.Type}, 
        {"Revenue (Millions)", type number}, 
        {"Metascore", Int64.Type}
    }),

    // List of genres
    GenreFilterList = { "Action", "Adventure", "Sci-Fi", Fantasy }

in

    #"Changed Type"

3. Reference the List in Power Query

After creating the list, you need to reference it in your Power Query script. To do this, follow these steps:

  • Navigate the “View” tab in the Power Query Editor, and select “Advanced Editor”.

Now in the script editor, you can reference your list variable (e.g., MyFilterList) by typing its name. Then click “Done” to apply the filter.

Common Problems and Solutions when Using List Filters in Power Query

Sometimes, using list filters in Power Query comes with some common issues. However, the following are some troubleshooting tips that can help you overcome them:

1. Handling Errors and Unexpected Results

If you come across certain errors or unexpected results when applying list filters, try double-checking the filter criteria to make sure they are correctly defined. Also, check if the data you’re filtering is in the right format and contains relevant information.

2. Handling Null or Empty List Filters

Also, it is important to handle null or empty list filters properly to avoid errors. For instance, you can use conditional statements or error-handling techniques to mitigate this issue.

3. Debugging and Testing List Filters

To debug and test list filters, you can use the Power Query preview feature to review the filtered data and check if it meets your needs. Also, don’t forget to add filters step-by-step as explained in this article to avoid errors.

Best Practices and Tips for Optimizing List Filters in Power Query

To ensure efficient and optimal performance of your list filters in Power Query, it is important to follow a few best practices. Below are some best practices to follow:

1. Limit the Size of Lists

It is better to limit the size of the lists you are working with to improve the speed of list filters, as filtering a large list can be time-consuming. Hence, consider narrowing down the data by using other filters or aggregations to reduce the number of items in the list.

2. Sort and Organize Lists

Also, sorting and organizing your lists can help improve performance when using list filters. You should arrange the data in a logical and structured way, to make it easier for Power Query to process the filters.

3. Cache and Refresh List Filters

Typically, when you apply a list filter, Power Query stores the filtered data in memory, which makes subsequent operations faster. However, if this data changes, you should consider refreshing the filter to keep your data up-to-date.

FAQs: How to Use a List as Filter Argument in Power Query

Is it possible to use a dynamic list as a filter argument in Power Query?

Yes, you can use a dynamic list as a filter argument in Power Query. Just create a dynamic list using functions like Excel tables, named ranges, or custom functions and ensure your filter criteria update as your data changes automatically.

What happens if my list filter returns no results?

Power Query will generate an empty table if your list filter returns no results.

Can you combine multiple lists as filter arguments in Power Query?

Yes, you can combine multiple lists as filter arguments in Power Query. You can make use of functions like List.Combine or List.Union to merge multiple lists into a single filter argument.

Conclusion

Power Query is a versatile tool that empowers users to effectively analyze and enhance data in Power BI.

By following this step-by-step guide, exploring advanced techniques, and best practices, you can effectively filter and manipulate data based on specific criteria.

Now that you have an understanding of how to use a list as filter arguments in Power Query, you can apply these concepts to analyze your data and unlock the full potential of Power Query.

I hope you enjoyed reading this article. You can also check this article on how to ignore slicers in Power BI measures.

Thanks for reading!