Daily DAX : Day 108 SUBSTITUTE

 The SUBSTITUTE function in Power BI's Data Analysis Expressions (DAX) is a text function that allows you to replace existing text with new text in a string. Here's how it works and its primary use case:

Syntax

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SUBSTITUTE(<text>, <old_text>, <new_text>[, <instance_num>])

    <text>: The original text string where you want to make the substitution.

    <old_text>: The text you want to replace.

    <new_text>: The text you want to use as the replacement.

    <instance_num> (optional): Specifies which occurrence of <old_text> to replace. If omitted, all occurrences are replaced.

Explanation

    The SUBSTITUTE function searches for <old_text> within <text> and replaces it with <new_text>. If <instance_num> is provided, only that specific instance of <old_text> is replaced. If <instance_num> is not specified, every instance of <old_text> is replaced.

Example

Here's a basic example:

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SUBSTITUTE("Hello World", "World", "Universe")

This would return "Hello Universe".

If you want to replace only the first instance:

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SUBSTITUTE("Hello Hello Hello", "Hello", "Hi", 1)

This would return "Hi Hello Hello".

Main Use Case

The primary use case for SUBSTITUTE in Power BI includes:

    Data Cleaning: It's extremely useful for cleaning data by correcting common text errors, standardizing text formats, or removing unwanted characters. For example, if you have a column with inconsistent naming (e.g., "Mr." and "Mr" for titles), you can standardize it.

    Text Manipulation in Reports: You might use SUBSTITUTE to alter text on-the-fly in your reports, like changing abbreviations to full names for better readability or replacing coded values with human-readable text.

    Dynamic Text Transformation: In scenarios where you need to dynamically adjust text based on user interaction or other data conditions in Power BI, SUBSTITUTE can be part of more complex DAX expressions to achieve this.

    Custom Calculations: When combined with other DAX functions, SUBSTITUTE can help in creating custom calculations or measures that involve string manipulation.

Remember, SUBSTITUTE is case-sensitive, so "Hello" and "hello" would be treated as different strings unless you adjust for case in your DAX expressions.

https://dax.guide/substitute/