id4_common.plans.peak_position#

Peak / centroid plans for 1D scans and 2D ``grid_scan``s (issue #59).

Public surface:

  • peak_pos() — diagnostic; returns a stats dict for any scan (1D or 2D). No motion.

  • cen() — move to the FWHM midpoint of a previous scan.

  • com() — move to the centroid (center-of-mass).

  • maxi() — move to the x at peak max.

  • mini() — move to the x at peak min.

For 2D grid_scan runs the move plans default to moving both scan motors to the 2D feature. Pass positioner= a single motor to project onto that axis instead, or positioner=[m1, m2] to be explicit.

Backward-compat aliases for callers from PR #54: peak (= com), pmax (= maxi), pmin (= mini).

Backend choice (no new pip deps):

  • apstools.utils.xy_statistics for 1D com / max / min / fwhm (already a dep).

  • scipy.signal for the FWHM-midpoint (cen) calculation in 1D.

  • scipy.ndimage for com / max / min / cen in 2D.

Module Contents#

id4_common.plans.peak_position.peak_pos(scan_id=-1, x=None, y=None)#

Compute peak statistics for one or more detectors of a previous scan.

Loads the scan from the shared session catalog (id4_common.utils.run_engine.cat), dispatches to the 1D or 2D backend based on the scan’s plan, and returns a nested dict.

Parameters:

  • scan_id (int, optional) – Catalog index. Default -1 (last scan); negative indices count from the end.

  • x (str, optional) – For 1D scans: motor (x-axis) field name. If None, picks the single motor or, for multi-motor 1D scans, the motor with the largest range. Ignored for 2D scans.

  • y (str or list of str, optional) – Detector (y-axis) field name(s). If None, uses every entry in start["hints"]["detectors"].

Returns:

Always carries "shape" and "axes" so callers can branch on dimensionality:

  • 1D: {"shape": (N,), "axes": [motor], "com": {det: x, ...}, "max": {det: (x, h), ...}, "min": {det: (x, h), ...}, "fwhm": {det: w, ...}, "cen": {det: x, ...}}

  • 2D: {"shape": (M, N), "axes": [m1, m2], "com": {det: (m1, m2), ...}, "max": {det: (m1, m2, h), ...}, "min": {det: (m1, m2, h), ...}, "cen": {det: (m1, m2), ...}, "fwhm": {det: (fwhm_m1, fwhm_m2), ...}}

Return type:

dict

id4_common.plans.peak_position.cen(scan_id=-1, positioner=None, detector=None, confirm=True)#

Move to the FWHM-midpoint of a previous scan.

Equivalent to bluesky PeakStats.cen. For asymmetric peaks this differs from com().

Parameters:

  • scan_id (int, optional) – Catalog index of the scan. Default -1 (last scan).

  • positioner (ophyd object or list, optional) – Device(s) to move. None → autodetected from the scan’s motors (single for 1D scans, both motors for 2D grid_scan).

  • detector (str, optional) – Detector field name. None → first hint from the scan.

  • confirm (bool, optional) – If True (default), prompts for multi-motor 1D scans and for scans older than 5 minutes. False skips every prompt.

See also

com(), maxi(), mini(), peak_pos()

id4_common.plans.peak_position.com(scan_id=-1, positioner=None, detector=None, confirm=True)#

Move to the centroid (center-of-mass) of a previous scan.

See cen() for parameter details.

See also

cen(), maxi(), mini(), peak_pos()

id4_common.plans.peak_position.maxi(scan_id=-1, positioner=None, detector=None, confirm=True)#

Move to the x-value at peak maximum of a previous scan.

See cen() for parameter details.

See also

cen(), com(), mini(), peak_pos()

id4_common.plans.peak_position.mini(scan_id=-1, positioner=None, detector=None, confirm=True)#

Move to the x-value at peak minimum of a previous scan.

See cen() for parameter details.

See also

cen(), com(), maxi(), peak_pos()

id4_common.plans.peak_position.peak(scan_id=-1, feature='centroid', positioner=None, detector=None, confirm=True)#

Backward-compat: dispatch by feature to cen() / com() / maxi() / mini().

Accepts the PR-#54 feature names ("centroid" / "x_at_max_y" / "x_at_min_y") and the new short names ("com" / "max" / "min" / "cen").

id4_common.plans.peak_position.pmax(scan_id=-1, positioner=None, detector=None, confirm=True)#

Alias of maxi() (PR #54 name).

id4_common.plans.peak_position.pmin(scan_id=-1, positioner=None, detector=None, confirm=True)#

Alias of mini() (PR #54 name).