source: sasview/src/sas/sascalc/dataloader/readers/sesans_reader.py @ 0ac6e11

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Last change on this file since 0ac6e11 was 0ac6e11, checked in by Adam Washington <adam.washington@…>, 7 years ago

Start fixing sesans smearing for time of flight

  • Property mode set to 100644
File size: 4.8 KB
Line 
1"""
2    SESANS reader (based on ASCII reader)
3
4    Reader for .ses or .sesans file format
5
6    Jurrian Bakker
7"""
8import logging
9import numpy as np
10import os
11from sas.sascalc.dataloader.data_info import Data1D
12
13# Check whether we have a converter available
14has_converter = True
15try:
16    from sas.sascalc.data_util.nxsunit import Converter
17except:
18    has_converter = False
19_ZERO = 1e-16
20
21
22class Reader:
23    """
24    Class to load sesans files (6 columns).
25    """
26    # File type
27    type_name = "SESANS"
28
29    # Wildcards
30    type = ["SESANS files (*.ses)|*.ses",
31            "SESANS files (*..sesans)|*.sesans"]
32    # List of allowed extensions
33    ext = ['.ses', '.SES', '.sesans', '.SESANS']
34
35    # Flag to bypass extension check
36    allow_all = True
37
38    def read(self, path):
39        """
40        Load data file
41
42        :param path: file path
43
44        :return: SESANSData1D object, or None
45
46        :raise RuntimeError: when the file can't be opened
47        :raise ValueError: when the length of the data vectors are inconsistent
48        """
49        if os.path.isfile(path):
50            basename = os.path.basename(path)
51            _, extension = os.path.splitext(basename)
52            if not (self.allow_all or extension.lower() in self.ext):
53                raise RuntimeError("{} has an unrecognized file extension".format(path))
54        else:
55            raise RunetimeError("{} is not a file".format(path))
56        with open(path, 'r') as input_f:
57            # Read in binary mode since GRASP frequently has no-ascii
58            # characters that brakes the open operation
59            line = input_f.readline()
60            params = {}
61            while not line.startswith("BEGIN_DATA"):
62                terms = line.split()
63                if len(terms) >= 2:
64                    params[terms[0]] = " ".join(terms[1:])
65                line = input_f.readline()
66            self.params = params
67            headers = input_f.readline().split()
68
69            data = np.loadtxt(input_f)
70            if data.size < 1:
71                raise RuntimeError("{} is empty".format(path))
72            x = data[:, headers.index("SpinEchoLength")]
73            dx = data[:, headers.index("SpinEchoLength_error")]
74            lam = data[:, headers.index("Wavelength")]
75            dlam = data[:, headers.index("Wavelength_error")]
76            y = data[:, headers.index("Depolarisation")]
77            dy = data[:, headers.index("Depolarisation_error")]
78
79            lam_unit = self._unit_fetch("Wavelength")
80            x, x_unit = self._unit_conversion(x, "A", self._unit_fetch("SpinEchoLength"))
81            dx, dx_unit = self._unit_conversion(
82                dx, lam_unit,
83                self._unit_fetch("SpinEchoLength"))
84            dlam, dlam_unit = self._unit_conversion(
85                dlam, lam_unit,
86                self._unit_fetch("Wavelength"))
87            y_unit = self._unit_fetch("Depolarisation")
88
89            output = Data1D(x=x, y=y, lam=lam, dy=dy, dx=dx, dlam=dlam,
90                            isSesans=True)
91
92            output.y_unit = y_unit
93            output.x_unit = x_unit
94            output.source.wavelength_unit = lam_unit
95            output.source.wavelength = lam
96            self.filename = output.filename = basename
97            output.xaxis(r"\rm{z}", x_unit)
98            # Adjust label to ln P/(lam^2 t), remove lam column refs
99            output.yaxis(r"\rm{ln(P)/(t \lambda^2)}", y_unit)
100            # Store loading process information
101            output.meta_data['loader'] = self.type_name
102            output.sample.name = params["Sample"]
103            output.sample.ID = params["DataFileTitle"]
104            output.sample.thickness = float(
105                self._unit_conversion(
106                    params["Thickness"], "cm", self._unit_fetch("Thickness"))[0])
107
108            output.sample.zacceptance = (
109                float(params["Theta_zmax"]),
110                self._unit_fetch("Theta_zmax"))
111
112            output.sample.yacceptance = (
113                float(params["Theta_ymax"]),
114                self._unit_fetch("Theta_ymax"))
115            return output
116
117    @staticmethod
118    def _unit_conversion(value, value_unit, default_unit):
119        """
120        Performs unit conversion on a measurement.
121
122        :param value: The magnitude of the measurement
123        :param value_unit: a string containing the final desired unit
124        :param default_unit: a string containing the units of the original measurement
125        :return: The magnitude of the measurement in the new units
126        """
127        # (float, string, string) -> float
128        if has_converter and value_unit != default_unit:
129            data_conv_q = Converter(value_unit)
130            value = data_conv_q(value, units=default_unit)
131            new_unit = default_unit
132        else:
133            new_unit = value_unit
134        return value, new_unit
135
136    def _unit_fetch(self, unit):
137        return self.params[unit+"_unit"]
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