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Fixed length catalog is an option and a fallback

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wassname
2015-12-02 16:15:01 +08:00
parent 82e02dc7f2
commit fde4d3add0
1 changed files with 19 additions and 5 deletions
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segpy/reader.py
+19 -5
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@@ -13,6 +13,7 @@ from segpy.toolkit import (extract_revision,
read_binary_reel_header,
read_trace_header,
catalog_traces,
catalog_fixed_length_traces,
read_binary_values,
REEL_HEADER_NUM_BYTES,
TRACE_HEADER_NUM_BYTES,
@@ -21,7 +22,7 @@ from segpy.toolkit import (extract_revision,
guess_textual_header_encoding)
def create_reader(fh, encoding=None, trace_header_format=TraceHeaderRev1, endian='>', progress=None, cache_directory=".segpy"):
def create_reader(fh, encoding=None, trace_header_format=TraceHeaderRev1, endian='>', progress=None, cache_directory=".segpy", fast=False):
"""Create a SegYReader (or one of its subclasses) based on performing
a scan of SEG Y data.
@@ -56,6 +57,9 @@ def create_reader(fh, encoding=None, trace_header_format=TraceHeaderRev1, endian
are interpreted as being relative to the directory containing
the SEG Y file. Absolute paths are used as is. If
cache_directory is None, caching is disabled.
fast: Boolean flag to try a quick fixed length catalog before inline or
CDP catalogs.
Raises:
ValueError: ``fh`` is unsuitable for some reason, such as not
@@ -112,7 +116,7 @@ def create_reader(fh, encoding=None, trace_header_format=TraceHeaderRev1, endian
reader = _load_reader_from_cache(cache_file_path, seg_y_path)
if reader is None:
reader = _make_reader(fh, encoding, trace_header_format, endian, progress)
reader = _make_reader(fh, encoding, trace_header_format, endian, progress, fast=fast)
if cache_directory is not None:
_save_reader_to_cache(reader, cache_file_path)
@@ -207,7 +211,7 @@ def _load_reader_from_cache(cache_file_path, seg_y_path):
return reader
def _make_reader(fh, encoding, trace_header_format, endian, progress):
def _make_reader(fh, encoding, trace_header_format, endian, progress, fast=False):
if encoding is None:
encoding = guess_textual_header_encoding(fh)
if encoding is None:
@@ -217,8 +221,18 @@ def _make_reader(fh, encoding, trace_header_format, endian, progress):
extended_textual_header = read_extended_textual_headers(fh, binary_reel_header, encoding)
revision = extract_revision(binary_reel_header)
bps = bytes_per_sample(binary_reel_header, revision)
trace_offset_catalog, trace_length_catalog, cdp_catalog, line_catalog = catalog_traces(fh, bps, trace_header_format,
endian, progress)
if fast:
try:
trace_offset_catalog, trace_length_catalog, cdp_catalog, line_catalog = catalog_fixed_length_traces(fh, binary_reel_header, trace_header_format,endian, progress)
except:
trace_offset_catalog, trace_length_catalog, cdp_catalog, line_catalog = catalog_traces(fh, bps, trace_header_format,endian, progress)
else:
try:
trace_offset_catalog, trace_length_catalog, cdp_catalog, line_catalog = catalog_traces(fh, bps, trace_header_format,endian, progress)
except:
fh.seek(REEL_HEADER_NUM_BYTES)
trace_offset_catalog, trace_length_catalog, cdp_catalog, line_catalog = catalog_fixed_length_traces(fh, binary_reel_header, trace_header_format,endian, progress)
if line_catalog is not None:
return SegYReader3D(fh, textual_reel_header, binary_reel_header, extended_textual_header, trace_offset_catalog,