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Explore and validate relationships in semantic models and dataframes

  • Članak

In this article, you learn to use the SemPy semantic link functions to discover and validate relationships in your Power BI semantic models and pandas DataFrames.

In data science and machine learning, it's important to understand the structure and relationships within your data. Power BI is a powerful tool that allows you to model and visualize these structures and relationships. To gain more insights or build machine learning models, you can dive deeper by using the semantic link functions in the SemPy library modules.

Data scientists and business analysts can use SemPy functions to list, visualize, and validate relationships in Power BI semantic models, or find and validate relationships in pandas DataFrames.

Prerequisites

  • Create a new notebook to copy/paste code into cells.

  • For Spark 3.4 and above, semantic link is available in the default runtime when using Fabric, and there's no need to install it. For Spark 3.3 or below, or to update to the latest version of semantic link, run the following command:

    %pip install -U semantic-link

  • Add a lakehouse to your notebook.

List relationships in semantic models

The list_relationships function in the sempy.fabric module returns a list of all relationships found in a Power BI semantic model. The list helps you understand the structure of your data and how different tables and columns are connected.

This function works by using semantic link to provide annotated DataFrames. The DataFrames include the necessary metadata to understand the relationships within the semantic model. The annotated DataFrames make it easy to analyze the semantic model's structure and use it in machine learning models or other data analysis tasks.

To use the list_relationships function, you first import the sempy.fabric module. Then you call the function by using the name or UUID of your Power BI semantic model, as shown in the following example:

import sempy.fabric as fabric

fabric.list_relationships("my_dataset")

The preceding code calls the list_relationships function with a Power BI semantic model called my_dataset. The function returns a pandas DataFrame with one row per relationship, allowing you to easily explore and analyze the relationships within the semantic model.

Note

Your notebook, Power BI dataset semantic model, and lakehouse can be located in the same workspace or in different workspaces. By default, SemPy tries to access your semantic model from:

  • The workspace of your lakehouse, if you attached a lakehouse to your notebook.
  • The workspace of your notebook, if there's no lakehouse attached.

If your semantic model isn't located in either of these workspaces, you must specify the workspace of your semantic model when you call a SemPy method.

Visualize relationships in semantic models

The plot_relationship_metadata function helps you visualize relationships in a semantic model so you can gain a better understanding of the model's structure. This function creates a graph that displays the connections between tables and columns. The graph makes it easier to understand the semantic model's structure and how different elements are related.

The following example shows how to use the plot_relationship_metadata function:

import sempy.fabric as fabric
from sempy.relationships import plot_relationship_metadata

relationships = fabric.list_relationships("my_dataset")
plot_relationship_metadata(relationships)

In the preceding code, the list_relationships function retrieves the relationships in the my_dataset semantic model, and the plot_relationship_metadata function creates a graph to visualize the relationships.

You can customize the graph by defining which columns to include, specifying how to handle missing keys, and providing more graphviz attributes.

Validate relationships in semantic models

Now that you have a better understanding of the relationships in your semantic model, you can use the list_relationship_violations function to validate these relationships and identify any potential issues or inconsistencies. The list_relationship_violations function helps you validate the content of your tables to ensure that they match the relationships defined in your semantic model.

By using this function, you can identify inconsistencies with the specified relationship multiplicity and address any issues before they impact your data analysis or machine learning models.

To use the list_relationship_violations function, first you import the sempy.fabric module and read the tables from your semantic model. Then, you call the function with a dictionary that maps table names to the DataFrames with table content.

The following example code shows how to list relationship violations:

import sempy.fabric as fabric

tables = {
    "Sales": fabric.read_table("my_dataset", "Sales"),
    "Products": fabric.read_table("my_dataset", "Products"),
    "Customers": fabric.read_table("my_dataset", "Customers"),
}

fabric.list_relationship_violations(tables)

The preceding code calls the list_relationship_violations function with a dictionary that contains the Sales, Products, and Customers tables from the my_dataset semantic model. You can customize the function by setting a coverage threshold, specifying how to handle missing keys, and defining the number of missing keys to report.

The function returns a pandas DataFrame with one row per relationship violation, allowing you to easily identify and address any issues within your semantic model. By using the list_relationship_violations function, you can ensure that your semantic model is consistent and accurate, allowing you to build more reliable machine learning models and gain deeper insights into your data.

Find relationships in pandas DataFrames

While the list_relationships, plot_relationships_df and list_relationship_violations functions in the Fabric module are powerful tools for exploring relationships within semantic models, you might also need to discover relationships within other data sources imported as pandas DataFrames.

This is where the find_relationships function in the sempy.relationship module comes into play.

The find_relationships function in the sempy.relationships module helps data scientists and business analysts discover potential relationships within a list of pandas DataFrames. By using this function, you can identify possible connections between tables and columns, allowing you to better understand the structure of your data and how different elements are related.

The following example code shows how to find relationships in pandas DataFrames:

from sempy.relationships import find_relationships

tables = [df_sales, df_products, df_customers]

find_relationships(tables)

The preceding code calls the find_relationships function with a list of three Pandas DataFrames: df_sales, df_products, and df_customers. The function returns a pandas DataFrame with one row per potential relationship, allowing you to easily explore and analyze the relationships within your data.

You can customize the function by specifying a coverage threshold, a name similarity threshold, a list of relationships to exclude, and whether to include many-to-many relationships.

Validate relationships in pandas DataFrames

After you discover potential relationships in your pandas DataFrames by using the find_relationships function, you can use the list_relationship_violations function to validate these relationships and identify any potential issues or inconsistencies.

The list_relationship_violations function validates the content of your tables to ensure that they match the discovered relationships. By using this function to identify inconsistencies with the specified relationship multiplicity, you can address any issues before they impact your data analysis or machine learning models.

The following example code shows how to find relationship violations in pandas DataFrames:

from sempy.relationships import find_relationships, list_relationship_violations

tables = [df_sales, df_products, df_customers]
relationships = find_relationships(tables)

list_relationship_violations(tables, relationships)

The preceding code calls the list_relationship_violations function with a list of three pandas DataFrames, df_sales, df_products, and df_customers, plus the relationships DataFrame from the find_relationships function. The list_relationship_violations function returns a pandas DataFrame with one row per relationship violation, allowing you to easily identify and address any issues within your data.

You can customize the function by setting a coverage threshold, specifying how to handle missing keys, and defining the number of missing keys to report.

By using the list_relationship_violations function with pandas DataFrames, you can ensure that your data is consistent and accurate, allowing you to build more reliable machine learning models and gain deeper insights into your data.

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