plot_xsecs

plot_xsecs(reactions, *, processes="all", layout="overlay", energy_unit="eV", xsec_unit="Mb", energy_log=True, xsecs_log=True, trim=True, shade=False, show_bands=False, palette=None, title=None, fig=None, ax=None, grid=True, show=True, save=False, filename="")

Plots photo cross sections for one or more reactions on shared axes. Handles unit conversion, log scaling, axis trimming, optional shading, and optional band-averaged bars. Reactions without cross-section data are skipped with a log message; returns None if nothing can be drawn.

Parameters

reactions : reaction-like or list of reaction-like

A single reaction (anything exposing xsecs_dict and band_xsecs) or a list of them. Their cross sections are overlaid.

processes : str or list[str] or None, optional

Which processes to draw. "all" (default) or None plots every process with data; a single key or list selects a subset. Valid keys: "photo_absorption", "photodecay". An invalid key raises KeyError.

layout : str, optional

"overlay" (default) draws all curves on one axes; "subplots" gives each curve its own stacked panel.

energy_unit : str, optional

Horizontal-axis unit: "eV" (default), "erg", "nm", or "um".

xsec_unit : str, optional

Cross-section unit: "Mb" (default), "cm^2", or "barn".

energy_log, xsecs_log : bool, optional

Log-scale the energy / cross-section axis. Default True.

trim : bool, optional

Tighten the energy axis to the positive data span. Default True.

shade : bool or float, optional

Shade the area under each curve. True uses a default alpha; a float sets the alpha explicitly. Default False.

show_bands : bool, optional

Overlay the band-averaged cross section as bars for every reaction that has them (see Reaction.band_xsecs). Default False.

palette : list[str] or None, optional

Colour-cycle override.

title : str or None, optional

Plot title. Defaults to the LaTeX equation for a single reaction, else empty.

fig, ax : matplotlib.figure.Figure / matplotlib.axes.Axes or None, optional

Existing figure/axes to draw on (overlay only). Created if None.

grid, show, save, filename : optional

Standard rendering controls.

Returns

tuple[matplotlib.figure.Figure, matplotlib.axes.Axes] or None

The figure and axes (overlay) or array of axes (subplots); None when no reaction has cross-section data.

Examples

from jaff.plotting import plot_xsecs

photo = net.reactions.photo_reactions()[0]
plot_xsecs(photo)                                   # one reaction, all processes
plot_xsecs(photo, shade=True, show_bands=True)      # shading + band bars
plot_xsecs(photo, energy_unit="nm", xsec_unit="cm^2")
plot_xsecs(net.reactions.photo_reactions())         # overlay several reactions