Extract metadata from a dataset
I would like to extract some metadata (for example the column names) from a dataset.
Is there any existing recipe or preparation processor doing that, or have I to write it myself in a plugin ?
Answers
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Hi,
I would suggest leveraging the Python APIs to retrieve the information you need, such as the metadata or corresponding schema, from these datasets:
https://doc.dataiku.com/dss/latest/python-api/datasets.html
https://doc.dataiku.com/dss/latest/python-api/rest-api-client/datasets.html
More information about available functions can be found at the bottom under the reference doc section.
Best,
Andrew -
So I understand the answer as "there isn't any existing solution" and I had to code it myself
I think it could be a good thing to add as a standard recipe / processor -
Hi,
Sure we appreciate the feedback and I'll forward it on your behalf to our Product team for further review.
Best,
Andrew
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Marlan Neuron 2020, Neuron, Registered, Dataiku Frontrunner Awards 2021 Finalist, Neuron 2021, Neuron 2022, Dataiku Frontrunner Awards 2021 Participant, Neuron 2023 Posts: 320 Neuron
Here's some code that may be helpful. It illustrates reading the schema and some other dataset attributes. This example is geared toward SQL datasets (our primary use) so some of the details may differ for other types of datasets.
ds = dataiku.Dataset('FEATURES') # location_info loc_info = ds.get_location_info() ds_info = loc_info['info'] if loc_info['locationInfoType'] == 'SQL' and 'table' not in ds_info: table = '<SQL Query>' else: table = ds_info['table'] print('Dataset Type: {}'.format(loc_info['locationInfoType'])) print('Connection Name: {}'.format(ds_info['connectionName'])) print('Database Type: {}'.format(ds_info['databaseType'])) print('Table Name: {}'.format(table)) # schema print('\nColumns in Dataset (Name - dss type / database type):') for col in ds.read_schema(): print('{0} - {1} / {2}'.format(col['name'], col['type'], col['originalType'])) # Note that ds.get_config() has all of above plus many other config items
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Hi @florianbriand
What did you want to do with the metadata? Is writing it into a file (e.g. a custom recipe) very convenient?
Herc -
For information, the plugin I wrote is as simple as :
import dataiku from dataiku.customrecipe import * import pandas as pd from pprint import pprint main_input_names = get_input_names_for_role('main_input') main_input_ds = dataiku.Dataset(main_input_names[0]) print("------------- INPUT -------------") pprint(main_input_ds) # For outputs, the process is the same: main_output_names = get_output_names_for_role('main_output') main_output_ds = dataiku.Dataset(main_output_names[0]) schema = main_input_ds.read_schema() # {name, type} for each column print("------------- SCHEMA -------------") pprint(schema) main_output_df = pd.DataFrame(schema) print("------------- OUTPUT -------------") pprint(main_output_df) main_output_ds.write_with_schema(main_output_df)
Because in my case, I didn't need anything else than the schema.
But there are probably other metadata which could be helpful.
From my side, the need is just to get the columns list to make things like :
- check if every column required in subsequent flow are provided and give user information about missing columns
- automatically configure some other recipes, via variables, with the input columns
- ...