mirror of
https://github.com/wassname/segpy.git
synced 2026-07-09 06:06:43 +08:00
Robert Smallshire
168 lines
8.2 KiB
Python
168 lines
8.2 KiB
Python
"""Tools for interoperability between Segpy and Numpy arrays."""
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import numpy as np
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from segpy.util import ensure_superset
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from segpy_numpy.dtypes import make_dtype
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class DimensionalityError:
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pass
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def extract_trace_header_field_3d(reader, field, null=None):
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"""Extract a single trace header field from all trace headers as an array.
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Args:
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reader: A SegYReader
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field: A header field
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"""
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shape = (reader.num_inlines(), reader.num_xlines())
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dtype = make_dtype(field.value_type.SEG_Y_TYPE)
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arr = _make_array(shape, dtype, null)
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field_name = field.name
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for inline_xline in reader.inline_xline_numbers():
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inline_number, xline_number = inline_xline
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trace_index = reader.trace_index(inline_xline)
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trace_header = reader.trace_header(trace_index)
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inline_index = reader.inline_numbers().index(inline_number)
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xline_index = reader.xline_numbers().index(xline_number)
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field_value = getattr(trace_header, field_name)
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arr[inline_index, xline_index] = field_value
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return arr
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def extract_trace(reader, trace_index, sample_numbers):
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"""Extract an single trace as a one-dimensional array.
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Args:
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reader: A SegYReader3D object.
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trace_index: The index of the trace to be extracted.
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sample_numbers: The sample numbers within each trace at which samples are to be extracted.
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This argument can be specified in three ways:
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None (the default) - All samples within the trace will be be extracted.
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sequence - When a sequence, such as a range or a list is provided only those samples at
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sample numbers corresponding to the items in the sequence will be extracted. The
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samples will always be extracted in increasing numeric order and duplicate entries
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will be ignored. For example sample_numbers=range(100, 200, 2) will extract alternate
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samples from sample number 100 to sample number 198 inclusive.
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slice - When a slice object is provided the slice will be applied to the sequence of all
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sample numbers. For example sample_numbers=slice(100, -100) will omit the first
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one hundred and the last one hundred samples, irrespective of their numbers.
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Returns:
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A one-dimensional array.
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"""
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if not reader.has_trace_index(trace_index):
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raise ValueError("Inline number {} not present in {}".format(trace_index, reader))
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sample_numbers = ensure_superset(range(0, reader.max_num_trace_samples()), sample_numbers)
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trace_sample_start = sample_numbers[0]
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trace_sample_stop = min(sample_numbers[-1] + 1, reader.num_trace_samples(trace_index))
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trace_samples = reader.trace_samples(trace_index, trace_sample_start, trace_sample_stop)
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arr = np.fromiter((trace_samples[sample_number - trace_sample_start] for sample_number in sample_numbers),
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make_dtype(reader.data_sample_format))
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return arr
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def extract_inline_3d(reader_3d, inline_number, xline_numbers=None, sample_numbers=None, null=None):
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"""Extract an inline as a two-dimensional array.
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Args:
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reader: A SegYReader3D object.
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inline_number: The number of the inline to be extracted.
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xline_numbers: The crossline numbers within the inline at which traces are to be extracted.
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This argument can be specified in three ways:
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None (the default) - All traces within the inline will be be extracted.
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sequence - When a sequence, such as a range or a list is provided only those traces at
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crossline numbers corresponding to the items in the sequence will be extracted. The
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traces will always be extracted in increasing numeric order and duplicate entries
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will be ignored. For example xline_numbers=range(100, 200, 2) will extract alternate
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traces from crossline number 100 to crossline number 198 inclusive.
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slice - When a slice object is provided the slice will be applied to the sequence of all
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crossline numbers. For example xline_numbers=slice(100, -100) will omit the first
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one hundred and the last one hundred traces, irrespective of their numbers.
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sample_numbers: The sample numbers within each trace at which samples are to be extracted.
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This argument can be specified in three ways:
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None (the default) - All samples within the trace will be be extracted.
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sequence - When a sequence, such as a range or a list is provided only those samples at
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sample numbers corresponding to the items in the sequence will be extracted. The
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samples will always be extracted in increasing numeric order and duplicate entries
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will be ignored. For example sample_numbers=range(100, 200, 2) will extract alternate
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samples from sample number 100 to sample number 198 inclusive.
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slice - When a slice object is provided the slice will be applied to the sequence of all
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sample numbers. For example sample_numbers=slice(100, -100) will omit the first
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one hundred and the last one hundred samples, irrespective of their numbers.
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null: A null value. When None is specified as the null value a masked array will be returned.
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Returns:
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A two-dimensional array. If null is None a masked array will be returned, otherwise
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a regular array will be returned. The first (slowest changing) index will correspond
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to the traces (index zero will correspond to the first crossline number). The
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second (fastest changing) index will correspond to the samples (index zero will
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correspond to the first sample number.
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"""
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if inline_number not in reader_3d.inline_numbers():
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raise ValueError("Inline number {} not present in {}".format(inline_number, reader_3d))
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xline_numbers = ensure_superset(reader_3d.xline_numbers(), xline_numbers)
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sample_numbers = ensure_superset(range(0, reader_3d.max_num_trace_samples()), sample_numbers)
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shape = (len(xline_numbers), len(sample_numbers))
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dtype = make_dtype(reader_3d.data_sample_format)
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array = _make_array(shape, dtype, null)
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if isinstance(sample_numbers, range):
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_populate_inline_array_over_sample_range(reader_3d, inline_number, xline_numbers, sample_numbers, array)
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else:
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_populate_inline_array_numbered_samples(reader_3d, inline_number, xline_numbers, sample_numbers, array)
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return array
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def _populate_inline_array_numbered_samples(reader, inline_number, xline_numbers, sample_numbers, array):
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for xline_index, xline_number in enumerate(xline_numbers):
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inline_xline_number = (inline_number, xline_number)
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if reader.has_trace_index(inline_xline_number):
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trace_index = reader.trace_index(inline_xline_number)
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num_trace_samples = reader.num_trace_samples(trace_index)
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trace_sample_start = sample_numbers[0]
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trace_sample_stop = min(sample_numbers[-1] + 1, num_trace_samples)
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trace_samples = reader.trace_samples(trace_index, trace_sample_start, trace_sample_stop)
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for sample_index, sample_number in enumerate(sample_numbers):
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array[xline_index, sample_index] = trace_samples[sample_number - trace_sample_start]
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def _populate_inline_array_over_sample_range(reader, inline_number, xline_numbers, sample_numbers, array):
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for xline_index, xline_number in enumerate(xline_numbers):
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inline_xline_number = (inline_number, xline_number)
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if reader.has_trace_index(inline_xline_number):
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trace_index = reader.trace_index(inline_xline_number)
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num_trace_samples = reader.num_trace_samples(trace_index)
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trace_sample_stop = min(sample_numbers.stop, num_trace_samples)
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trace_samples = reader.trace_samples(trace_index, sample_numbers.start, trace_sample_stop)
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source_slice = slice(sample_numbers.start, trace_sample_stop, sample_numbers.step)
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array[xline_index, :] = trace_samples[source_slice]
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def _make_array(shape, dtype, null=None):
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"""Make an array"""
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if null is None:
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return np.ma.masked_all(shape, dtype)
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array = np.empty(shape, dtype)
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array.fill(null)
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return array
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