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 _insist_header(headers, name): if name not in headers: raise FileContentsException( "Missing {} column in spin echo data".format(name))
[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"]