Autoreduction

Python scripts for automatic reduction of SANS data are provided in the scripts/autoreduction/ directory. These scripts are designed to be run by the SNS web monitor but also from the command line.

Required arguments for the scripts include:

  • Events Nexus file, e.g., /SNS/EQSANS/IPTS-20196/nexus/EQSANS_89157.nxs.h5

  • Output directory, e.g., /SNS/EQSANS/IPTS-20196/shared/autoreduction/

Example of the autoreduction service running the script:

python reduce_EQSANS.py \
    /SNS/EQSANS/IPTS-20196/nexus/EQSANS_89157.nxs.h5 \
    /SNS/EQSANS/IPTS-20196/shared/autoreduction/

User can also run the script manually, for instance:

python reduce_EQSANS.py \
    /SNS/EQSANS/IPTS-20196/nexus/EQSANS_89157.nxs.h5 \
    /tmp --no_publish

This call will not publish the results to the live data server, but will save report file EQSANS_89157.html in the /tmp directory. User can point the web browser to the generated report file file:///tmp/EQSANS_89157.html.

Input Configuration

The autoreduction script will automatically look for an input configuration file in three locations, in the following order of precedence:

  1. Under the shared directory of the current IPTS and taking into account the run number. For example, for IPTS-20196 and run number 89157, the script will look for /SNS/EQSANS/IPTS-20196/shared/autoreduce/89157/reduction_options_89157.json.

  2. Under the shared directory of the current IPTS. For example, for IPTS-20196, the script will look for /SNS/EQSANS/IPTS-20196/shared/autoreduce/reduction_options.json.

  3. File /SNS/EQSANS/shared/autoreduce/reduction_options.json.

Output Files

For IPTS-20196 and run number 89157, all reduction files are saved under directory /SNS/EQSANS/IPTS-20196/shared/autoreduction/89157/. Among them:

  1. EQSANS_89157.html - the same report that shows up in the web monitor.

  2. EQSANS_89157_Iq.dat and EQSANS_89157_Iq.png - 1D reduced data file and plot.

  3. EQSANS_89157_Iqxqy.dat, EQSANS_89157_Iqxqy.h5, EQSANS_89157_Iqxqy.png - 2D reduced data files and plot.

  4. EQSANS_89157_processed.nxs - I(lambda) per detector pixel.

  5. EQSANS_162568_reduction_log.hdf - HDF5 file with reduction-derived parameters (transmission, center, etc).

  6. autoreduce_89157.log - log file with detailed information about the reduction steps at level INFO and above.

  7. reduction_options_89157.json - input configuration options, completed with any missing default values. If User requests to autoreduce the same run again, this file will be used as input configuration.

Additionally, if GPR analysis is enabled (which it is by default), the following files will also be generated:

  1. EQSANS_89157_Iq_gpr.png - High-resolution plot showing the GPR fit alongside the experimental data.

  2. EQSANS_89157_Iq_gpr.dat - ASCII file with the GPR-fitted I(Q) profile including uncertainties.

For reductions with multiple I(Q) profiles (wedges or time slices), separate GPR files are created for each:

  • EQSANS_89157_wedge_0_Iq_gpr.png, EQSANS_89157_wedge_0_Iq_gpr.dat

  • EQSANS_89157_wedge_1_Iq_gpr.png, EQSANS_89157_wedge_1_Iq_gpr.dat

  • and so on for each wedge or time slice.

Gaussian Process Regression Analysis

The EQSANS autoreduction now includes Gaussian Process Regression (GPR) analysis of the calculated I(Q) profiles. This analysis provides uncertainty-quantified fits to your scattering data and appears directly in the HTML report.

What GPR Does

GPR fits a smooth curve through your I(Q) data while accounting for measurement uncertainties. It gives you:

  • A noise-reduced representation of your scattering profile

  • Quantified uncertainties on the fit

  • Better visualization of underlying trends in noisy data

The algorithm uses log-space transformations optimized for SANS data and includes iterative background estimation. Interactive Plotly plots are embedded in the HTML report, allowing you to zoom and explore your data.

Configuration

GPR analysis runs automatically by default. If you want to disable it, add this to your reduction configuration JSON file:

{
    "configuration": {
        "enableGPR": false
    }
}

Error Handling

GPR analysis is designed to never break your reduction. If GPR fails for any reason:

  • The failure is logged but doesn’t stop the reduction

  • Other reduction outputs are still generated normally

  • Error details appear in the log file

This means you can safely leave GPR enabled even for challenging datasets.

Resubmitting Autoreduction

User can resubmit the autoreduction for a given run, perhaps after modifying one of the reduction options files under the current IPTS, then clicking the reduction link located at the bottom on the web monitor page for that run. For example:

click the reduction link

TroubleShooting

If autoreduction fails, any log error messages as well as the traceback will be saved in the HTML report file as well as published to the live data server (if option --no_publish is not used).

Livereduction

Python scripts for automatic reduction of SANS data are provided in the scripts/livereduction/ directory. These scripts are meant to be run automatically by the live reduction server, never directly by the User.