Access Scan Data¶

A guide to accessing scan data after acquisition. This guide assumes you are comfortable with running a simple scan and observing the live data.

Steps¶

0. Run a scan¶

For an intro to running scans, see the example linked above. We will use the scan from that example, but assign it to a variable in our console:

    scan_report = scans.line_scan(dev.samx, -1, 1, steps=5, exp_time=0.1, relative=False)

1. Inspect the output from a scan you have just run¶

Having run the scan above, we can see inspect its status:

scan_report

ScanReport:
--------------------
    Status: COMPLETED
    Start time: ...
    End time: ...
    Elapsed time: ... s
    Scan ID: ...
    Scan number: ...
    Number of points: 5
    File: ...

2. Inspect the latest scan from history¶

Fetch the most recent scan history entry:

latest = bec.history[-1]
latest

ScanDataContainer:
    Start time: ...
    End time: ...
    Elapsed time: ... s
    Scan ID: ...
    Scan number: ...
    Scan name: line_scan
    Status: closed
    Number of points (monitored): 5
    File: ...

This gives you a handle to the scan data after execution.

3. Read one signal from the stored result¶

For example, inspect the recorded motor values for samx:

This returns arrays of timestamps and values collected during the scan, which you can use for further analysis:

latest.devices.samx.samx.read()

{'timestamp': array([1.77496343e+09, 1.77496343e+09, 1.77496343e+09, 1.77496344e+09,
        1.77496344e+09]),
 'value': array([-0.99140924, -0.49119309, -0.00282538,  0.49814051,  0.99329906])}

Each entry represents one sampled point from the scan, so history is not just a final snapshot. It preserves the full recorded series for later plotting, fitting, or custom analysis workflows.

4. Access the stored data¶

For each scan, an HDF5 file is written containing all the recorded signals and additional metadata about the scan which was run. It can be found in the File: entry in the scan report, both for an active scan and one obtained from the history. You can open this file with your preferred HDF5 viewer, or with h5py in Python. For an introduction to working with the BEC HDF5 file structure, see Open BEC HDF5 files with h5py and Open BEC HDF5 files with silx for a GUI-based approach.