Source code for validphys.lhapdfset

    Module containing an LHAPDF class compatible with validphys
    using the official lhapdf python interface.

    The ``.members`` and ``.central_member`` of the ``LHAPDFSet`` are
    LHAPDF objects (the typical output from ``mkPDFs``) and can be used normally.

    >>> from validphys.lhapdfset import LHAPDFSet
    >>> pdf = LHAPDFSet("NNPDF40_nnlo_as_01180", "replicas")
    >>> len(pdf.members)
    >>> pdf.central_member.alphasQ(91.19)
    >>> pdf.members[0].xfxQ2(0.5, 15625)
    {-5: 6.983360500601136e-05,
    -4: 0.0021818063617227604,
    -3: 0.00172453472243952,
    -2: 0.0010906577230485718,
    -1: 0.0022049272225017286,
    1: 0.020051104853608722,
    2: 0.0954139944889494,
    3: 0.004116641378803191,
    4: 0.002180124185625795,
    5: 6.922722705177504e-05,
    21: 0.007604124516892057}
import logging

import numpy as np

from validphys.lhapdf_compatibility import make_pdf

log = logging.getLogger(__name__)

[docs]class LHAPDFSet: """Wrapper for the lhapdf python interface. Once instantiated this class will load the PDF set from LHAPDF. If it is a T0 set only the CV will be loaded. """ def __init__(self, name, error_type): self._name = name self._error_type = error_type if self.is_t0: # If at this point we already know this is a T0 set, load only the CV self._lhapdf_set = make_pdf(name, 0) else: self._lhapdf_set = make_pdf(name) self._flavors = None @property def is_t0(self): """Check whether we are in t0 mode""" return self._error_type == "t0" @property def n_members(self): """Return the number of active members in the PDF set""" return len(self.members) @property def members(self): """Return the members of the set the special error type t0 returns only member 0 """ if self.is_t0: return self._lhapdf_set[0:1] return self._lhapdf_set @property def central_member(self): """Returns a reference to member 0 of the PDF list""" return self._lhapdf_set[0]
[docs] def xfxQ(self, x, Q, n, fl): """Return the PDF value for one single point for one single member If the flavour is not included in the PDF (for instance top/antitop) return 0.0 """ member_pdf = self.members[n] res = member_pdf.xfxQ(x, Q) return res.get(fl, 0.0)
@property def flavors(self): """Returns the list of accepted flavors by the LHAPDF set""" if self._flavors is None: self._flavors = self.members[0].flavors() return self._flavors
[docs] def grid_values(self, flavors: np.ndarray, xgrid: np.ndarray, qgrid: np.ndarray): """Returns the PDF values for every member for the required flavours, points in x and pointx in q The return shape is (members, flavors, xgrid, qgrid) Return ------ ndarray of shape (members, flavors, xgrid, qgrid) Examples -------- >>> import numpy as np >>> from validphys.lhapdfset import LHAPDFSet >>> pdf = LHAPDFSet("NNPDF40_nnlo_as_01180", "replicas") >>> xgrid = np.random.rand(10) >>> qgrid = np.random.rand(3) >>> flavs = np.arange(-4,4) >>> flavs[4] = 21 >>> results = pdf.grid_values(flavs, xgrid, qgrid) """ # Create an array of x and q of equal length for LHAPDF xarr, qarr = (g.ravel() for g in np.meshgrid(xgrid, qgrid)) # Ask LHAPDF for the values and swap the flavours and xgrid-qgrid axes raw = np.array([member.xfxQ(flavors, xarr, qarr) for member in self.members]).swapaxes(1, 2) # Unroll the xgrid-qgrid axes return raw.reshape(self.n_members, len(flavors), len(xgrid), len(qgrid))