Data access and discovery

This tutorial demonstrates common workflows for discovering and reading LEGEND data using LegendDataManagement.jl. It assumes that a valid configuration file is available and referenced via the LEGEND_DATA_CONFIG environment variable.

Setup

Ensure the configuration file is available to Julia:

export LEGEND_DATA_CONFIG="/path/to/legend_data_config.json"

Load the required packages:

using LegendDataManagement
using LegendHDF5IO

Opening a dataset

A dataset is opened by name as defined in the configuration file.

l200 = LegendData(:l200)

The returned LegendData object serves as the main entry point for accessing data tiers and metadata.

Inspecting available data tiers

With the search_disk function, you can check what kind of data is available through the LegendData object.

Check for available DataTier values with:

search_disk(DataTier, l200.tier[])

Check for available DataCategory values with:

search_disk(DataCategory, l200.tier[:raw])

Data selectors

Data selection is performed using data selectors rather than hard-coded paths. Common selectors include:

• DataCategory(:cal)
• DataPeriod(:p03)
• DataRun(:r001)
• DetectorID(:V08682A)

Reading data

Data can be loaded using read_ldata. First, specify the LegendData object and DataTier, then provide selectors to restrict the data to the subset you want to read.

data = read_ldata(l200, :jlhit, DataCategory(:cal), DataPeriod(:p03), DataRun(:r001), DetectorID(:V08682A))

See Reading data with read_ldata for links to further examples and the API reference.