Source code for sas.sascalc.dataloader.readers.sesans_reader
"""
SESANS reader (based on ASCII reader)
Reader for .ses or .sesans file format
Jurrian Bakker
"""
import os
import numpy as np
from ..file_reader_base_class import FileReader
from ..data_info import plottable_1D, DataInfo
from ..loader_exceptions import FileContentsException
# Check whether we have a converter available
has_converter = True
try:
from sas.sascalc.data_util.nxsunit import Converter
except ImportError:
has_converter = False
_ZERO = 1e-16
[docs]class Reader(FileReader):
"""
Class to load sesans files (6 columns).
"""
# File type
type_name = "SESANS"
## Wildcards
type = ["SESANS files (*.ses)|*.ses",
"SESANS files (*..sesans)|*.sesans"]
# List of allowed extensions
ext = ['.ses', '.SES', '.sesans', '.SESANS']
# Flag to bypass extension check
allow_all = True
[docs] def get_file_contents(self):
self.current_datainfo = DataInfo()
self.current_dataset = plottable_1D(np.array([]), np.array([]))
self.current_datainfo.isSesans = True
self.output = []
line = self.nextline()
params = {}
while line and not line.startswith("BEGIN_DATA"):
terms = line.split()
if len(terms) >= 2:
params[terms[0]] = " ".join(terms[1:])
line = self.nextline()
self.params = params
if "FileFormatVersion" not in self.params:
raise FileContentsException("SES file missing FileFormatVersion")
if float(self.params["FileFormatVersion"]) >= 2.0:
raise FileContentsException("SASView only supports SES version 1")
if "SpinEchoLength_unit" not in self.params:
raise FileContentsException("SpinEchoLength has no units")
if "Wavelength_unit" not in self.params:
raise FileContentsException("Wavelength has no units")
if params["SpinEchoLength_unit"] != params["Wavelength_unit"]:
raise FileContentsException(
"The spin echo data has rudely used "
"different units for the spin echo length "
"and the wavelength. While sasview could "
"handle this instance, it is a violation "
"of the file format and will not be "
"handled by other software.")
headers = self.nextline().split()
self._insist_header(headers, "SpinEchoLength")
self._insist_header(headers, "Depolarisation")
self._insist_header(headers, "Depolarisation_error")
self._insist_header(headers, "Wavelength")
data = np.loadtxt(self.f_open)
if data.shape[1] != len(headers):
raise FileContentsException(
"File has {} headers, but {} columns".format(
len(headers),
data.shape[1]))
if not data.size:
raise FileContentsException("{} is empty".format(self.filepath))
x = data[:, headers.index("SpinEchoLength")]
if "SpinEchoLength_error" in headers:
dx = data[:, headers.index("SpinEchoLength_error")]
else:
dx = x * 0.05
lam = data[:, headers.index("Wavelength")]
if "Wavelength_error" in headers:
dlam = data[:, headers.index("Wavelength_error")]
else:
dlam = lam * 0.05
y = data[:, headers.index("Depolarisation")]
dy = data[:, headers.index("Depolarisation_error")]
lam_unit = self._unit_fetch("Wavelength")
x, x_unit = self._unit_conversion(x, "A",
self._unit_fetch(
"SpinEchoLength"))
dx, dx_unit = self._unit_conversion(
dx, lam_unit,
self._unit_fetch("SpinEchoLength"))
dlam, dlam_unit = self._unit_conversion(
dlam, lam_unit,
self._unit_fetch("Wavelength"))
y_unit = self._unit_fetch("Depolarisation")
self.current_dataset.x = x
self.current_dataset.y = y
self.current_dataset.lam = lam
self.current_dataset.dy = dy
self.current_dataset.dx = dx
self.current_dataset.dlam = dlam
self.current_datainfo.isSesans = True
self.current_datainfo._yunit = y_unit
self.current_datainfo._xunit = x_unit
self.current_datainfo.source.wavelength_unit = lam_unit
self.current_datainfo.source.wavelength = lam
self.current_datainfo.filename = os.path.basename(self.f_open.name)
self.current_dataset.xaxis(r"\rm{z}", x_unit)
# Adjust label to ln P/(lam^2 t), remove lam column refs
self.current_dataset.yaxis(r"\rm{ln(P)/(t \lambda^2)}", y_unit)
# Store loading process information
self.current_datainfo.meta_data['loader'] = self.type_name
self.current_datainfo.sample.name = params["Sample"]
self.current_datainfo.sample.ID = params["DataFileTitle"]
self.current_datainfo.sample.thickness = self._unit_conversion(
float(params["Thickness"]), "cm",
self._unit_fetch("Thickness"))[0]
self.current_datainfo.sample.zacceptance = (
float(params["Theta_zmax"]),
self._unit_fetch("Theta_zmax"))
self.current_datainfo.sample.yacceptance = (
float(params["Theta_ymax"]),
self._unit_fetch("Theta_ymax"))
self.send_to_output()
[docs] @staticmethod
def _unit_conversion(value, value_unit, default_unit):
"""
Performs unit conversion on a measurement.
:param value: The magnitude of the measurement
:param value_unit: a string containing the final desired unit
:param default_unit: string with the units of the original measurement
:return: The magnitude of the measurement in the new units
"""
# (float, string, string) -> float
if has_converter and value_unit != default_unit:
data_conv_q = Converter(default_unit)
value = data_conv_q(value, units=value_unit)
new_unit = default_unit
else:
new_unit = value_unit
return value, new_unit
[docs] def _unit_fetch(self, unit):
return self.params[unit+"_unit"]