Recipes: How do I …?

This page contains frequently used code-snippets (“recipes”). Below, da refers to a data array. The examples generally assume that data is in “tof” unit (time-of-flight), i.e., no unit conversion was applied yet, and that there is a “spectrum” dimension in addition to the “tof” dimension. Replace these by the actual dimensions as required.

General

Compute total counts per pixel

counts = da.sum('tof')  # for histogrammed data
counts = da.bins.sum().sum('tof')  # for binned event data

Event data

Compute number of events

da.bins.size()  # events per bin (ignoring event weights and event masks)
da.bins.size().sum()  # total events from all non-masked bins

If the events have been normalized the event weights may differ from 1 and bins.sum() should be used instead of bins.size(). This also respects event masks:

da.bins.sum()  # effective events per bin
da.bins.sum().sum()  # total effective events from all non-masked bins

Mask a time-of-flight region such as a prompt-pulse

tof = sc.array(dims=['tof'], unit='ms', values=[tof_min, mask_start, mask_end, tof_max])
da = da.bin(tof=tof)  # bin in 'tof', updating prior 'tof' binning if present
da.masks['prompt_pulse'] = (tof >= tof['tof', 1]) & (tof < tof['tof', 2])

Plotting

Plot a single spectrum

da['spectrum', index].plot()  # plot spectrum with given index
# plot spectrum with given spectrum-number, provided da.coords['spectrum'] exists
da['spectrum', sc.scalar(spectrum_number)].plot()

Plot comparison of multiple spectra

spectra = {}
spectra['name1'] = da1['spectrum', index1]
spectra['name2'] = da1['spectrum', index2]
spectra['name3'] = da2['spectrum', index3]
sc.plot(spectra)