def hessian_from_lincomb(pdf, V, set_name=None, folder=None, db=None, extra_fields=None):
"""Construct a new LHAPDF grid from a linear combination of members"""
# preparing output folder
neig = V.shape[1]
base = applwrap.getlhapdfpath()[-1] + "/" + str(pdf) + "/" + str(pdf)
if set_name is None:
set_name = str(pdf) + "_hessian_" + str(neig)
if folder is None:
folder = ""
set_root = os.path.join(folder, set_name)
if not os.path.exists(set_root):
os.makedirs(os.path.join(set_root))
# copy replica 0
shutil.copy(base + "_0000.dat", set_root + "/" + set_name + "_0000.dat")
with open(base + ".info", "r") as inn, open(set_root + "/" + set_name + ".info", "w") as out:
for l in inn.readlines():
if l.find("SetDesc:") >= 0:
out.write('SetDesc: "Hessian ' + str(pdf) + '_hessian"\n')
elif l.find("NumMembers:") >= 0:
out.write("NumMembers: " + str(neig + 1) + "\n")
elif l.find("ErrorType: replicas") >= 0:
out.write("ErrorType: symmhessian\n")
else:
out.write(l)
if extra_fields is not None:
yaml.dump(extra_fields, out, default_flow_style=False)
headers, grids = load_all_replicas(pdf, db=db)
hess_name = set_root + "/" + set_name
result = (big_matrix(grids).dot(V)).add(grids[0], axis=0)
hess_header = b"PdfType: error\nFormat: lhagrid1\n"
for column in result.columns:
write_replica(column + 1, hess_name, hess_header, result[column])
return set_root
def get_lha_paths():
return applwrap.getlhapdfpath()
