How to use the segyio._segyio.init_line_metrics function in segyio

if mmap: _segyio.mmap(f)

        binary_header = _segyio.read_binaryheader(f)
        ilb = 189
        xlb = 193

        metrics = _segyio.init_metrics(f, binary_header, ilb, xlb)

        sorting = metrics['sorting']
        trace_count = metrics['trace_count']
        inline_count = metrics['iline_count']
        crossline_count = metrics['xline_count']
        offset_count = metrics['offset_count']

        line_metrics = _segyio.init_line_metrics(sorting, trace_count, inline_count, crossline_count, offset_count)

        metrics.update(line_metrics)

        iline_indexes = numpy.zeros(metrics['iline_count'], dtype=numpy.uintc)
        xline_indexes = numpy.zeros(metrics['xline_count'], dtype=numpy.uintc)
        offsets       = numpy.zeros(metrics['offset_count'], dtype=numpy.uintc)
        _segyio.init_indices(f, metrics, iline_indexes, xline_indexes, offsets)

        return f, metrics, iline_indexes, xline_indexes

def test_fread_trace0(self):
        f = _segyio.open(self.filename, "r")

        binary_header = _segyio.read_binaryheader(f)
        ilb = 189
        xlb = 193

        metrics = _segyio.init_metrics(f, binary_header, ilb, xlb)

        sorting = metrics['sorting']
        trace_count = metrics['trace_count']
        inline_count = metrics['iline_count']
        crossline_count = metrics['xline_count']
        offset_count = metrics['offset_count']

        line_metrics = _segyio.init_line_metrics(sorting, trace_count, inline_count, crossline_count, offset_count)

        iline_indexes = numpy.zeros(metrics['iline_count'], dtype=numpy.uintc)
        xline_indexes = numpy.zeros(metrics['xline_count'], dtype=numpy.uintc)
        offsets       = numpy.zeros(metrics['offset_count'], dtype=numpy.uintc)
        _segyio.init_indices(f, metrics, iline_indexes, xline_indexes, offsets)

        with self.assertRaises(KeyError):
            _segyio.fread_trace0(0, len(xline_indexes), line_metrics['iline_stride'], offset_count, iline_indexes, "inline")

        with self.assertRaises(KeyError):
            _segyio.fread_trace0(2, len(iline_indexes), line_metrics['xline_stride'], offset_count, xline_indexes, "crossline")

        value = _segyio.fread_trace0(1, len(xline_indexes), line_metrics['iline_stride'], offset_count, iline_indexes, "inline")
        self.assertEqual(value, 0)

        value = _segyio.fread_trace0(2, len(xline_indexes), line_metrics['iline_stride'], offset_count, iline_indexes, "inline")

sorting = metrics['sorting']
        trace_count = metrics['trace_count']
        inline_count = metrics['iline_count']
        crossline_count = metrics['xline_count']
        offset_count = metrics['offset_count']

        metrics = _segyio.init_line_metrics(sorting, trace_count, inline_count, crossline_count, offset_count)

        self.assertEqual(metrics['xline_length'], 5)
        self.assertEqual(metrics['xline_stride'], 5)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 1)

        # (sorting, trace_count, inline_count, crossline_count, offset_count)
        metrics = _segyio.init_line_metrics(1, 15, 3, 5, 1)

        self.assertEqual(metrics['xline_length'], 3)
        self.assertEqual(metrics['xline_stride'], 1)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 3)

        metrics = _segyio.init_line_metrics(2, 15, 3, 5, 1)

        self.assertEqual(metrics['xline_length'], 3)
        self.assertEqual(metrics['xline_stride'], 5)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 1)

metrics = _segyio.init_line_metrics(sorting, trace_count, inline_count, crossline_count, offset_count)

        self.assertEqual(metrics['xline_length'], 5)
        self.assertEqual(metrics['xline_stride'], 5)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 1)

        # (sorting, trace_count, inline_count, crossline_count, offset_count)
        metrics = _segyio.init_line_metrics(1, 15, 3, 5, 1)

        self.assertEqual(metrics['xline_length'], 3)
        self.assertEqual(metrics['xline_stride'], 1)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 3)

        metrics = _segyio.init_line_metrics(2, 15, 3, 5, 1)

        self.assertEqual(metrics['xline_length'], 3)
        self.assertEqual(metrics['xline_stride'], 5)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 1)

def test_line_metrics(self):
        f = _segyio.open(self.filename, "r")

        binary_header = _segyio.read_binaryheader(f)
        ilb = 189
        xlb = 193
        metrics = _segyio.init_metrics(f, binary_header, ilb, xlb)
        _segyio.close(f)

        sorting = metrics['sorting']
        trace_count = metrics['trace_count']
        inline_count = metrics['iline_count']
        crossline_count = metrics['xline_count']
        offset_count = metrics['offset_count']

        metrics = _segyio.init_line_metrics(sorting, trace_count, inline_count, crossline_count, offset_count)

        self.assertEqual(metrics['xline_length'], 5)
        self.assertEqual(metrics['xline_stride'], 5)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 1)

        # (sorting, trace_count, inline_count, crossline_count, offset_count)
        metrics = _segyio.init_line_metrics(1, 15, 3, 5, 1)

        self.assertEqual(metrics['xline_length'], 3)
        self.assertEqual(metrics['xline_stride'], 1)
        self.assertEqual(metrics['iline_length'], 5)
        self.assertEqual(metrics['iline_stride'], 3)

        metrics = _segyio.init_line_metrics(2, 15, 3, 5, 1)