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Version: 0.16.16

How to quickly connect to a single file using Pandas

In this guide we will demonstrate how to use Pandas to connect to data stored in files on a filesystem. In this example we will specifically be connecting to data in .csv format. However, GX supports most read methods available through Pandas.

Prerequisites​

Steps​

1. Import the Great Expectations module and instantiate a Data Context​

The code to import Great Expectations and instantiate a Data Context is:

import great_expectations as gx

context = gx.get_context()

2. Specify a file to read into a Data Asset​

Great Expectations supports reading the data in individual files directly into a Validator using Pandas. To do this, we will run the code:

validator = context.sources.pandas_default.read_csv(
    "https://raw.githubusercontent.com/great-expectations/gx_tutorials/main/data/yellow_tripdata_sample_2019-01.csv"
)
Using Pandas to connect to different file types

In this example, we are connecting to a csv file. However, Great Expectations supports connecting to most types of files that Pandas has read_* methods for.

Because you will be using Pandas to connect to these files, the specific add_*_asset methods that will be available to you will be determined by your currently installed version of Pandas.

For more information on which Pandas read_* methods are available to you as add_*_asset methods, please reference the official Pandas Input/Output documentation for the version of Pandas that you have installed.

In the GX Python API, add_*_asset methods will require the same parameters as the corresponding Pandas read_* method, with one caveat: In Great Expectations, you will also be required to provide a value for an asset_name parameter.

Next steps​

Now that you have a Validator, you can immediately move on to creating Expectations. For more information, please see: