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762 lines
28 KiB
Python
762 lines
28 KiB
Python
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"""
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Read SAS7BDAT files
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Based on code written by Jared Hobbs:
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https://bitbucket.org/jaredhobbs/sas7bdat
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See also:
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https://github.com/BioStatMatt/sas7bdat
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Partial documentation of the file format:
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https://cran.r-project.org/package=sas7bdat/vignettes/sas7bdat.pdf
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Reference for binary data compression:
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http://collaboration.cmc.ec.gc.ca/science/rpn/biblio/ddj/Website/articles/CUJ/1992/9210/ross/ross.htm
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"""
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from collections import abc
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from datetime import datetime, timedelta
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import struct
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import numpy as np
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from pandas.errors import EmptyDataError, OutOfBoundsDatetime
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import pandas as pd
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from pandas.io.common import get_filepath_or_buffer
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from pandas.io.sas._sas import Parser
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import pandas.io.sas.sas_constants as const
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from pandas.io.sas.sasreader import ReaderBase
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def _convert_datetimes(sas_datetimes: pd.Series, unit: str) -> pd.Series:
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"""
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Convert to Timestamp if possible, otherwise to datetime.datetime.
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SAS float64 lacks precision for more than ms resolution so the fit
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to datetime.datetime is ok.
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Parameters
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----------
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sas_datetimes : {Series, Sequence[float]}
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Dates or datetimes in SAS
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unit : {str}
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"d" if the floats represent dates, "s" for datetimes
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Returns
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-------
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Series
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Series of datetime64 dtype or datetime.datetime.
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"""
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try:
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return pd.to_datetime(sas_datetimes, unit=unit, origin="1960-01-01")
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except OutOfBoundsDatetime:
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if unit == "s":
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return sas_datetimes.apply(
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lambda sas_float: datetime(1960, 1, 1) + timedelta(seconds=sas_float)
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)
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elif unit == "d":
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return sas_datetimes.apply(
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lambda sas_float: datetime(1960, 1, 1) + timedelta(days=sas_float)
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)
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else:
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raise ValueError("unit must be 'd' or 's'")
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class _subheader_pointer:
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pass
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class _column:
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pass
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# SAS7BDAT represents a SAS data file in SAS7BDAT format.
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class SAS7BDATReader(ReaderBase, abc.Iterator):
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"""
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Read SAS files in SAS7BDAT format.
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Parameters
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----------
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path_or_buf : path name or buffer
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Name of SAS file or file-like object pointing to SAS file
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contents.
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index : column identifier, defaults to None
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Column to use as index.
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convert_dates : boolean, defaults to True
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Attempt to convert dates to Pandas datetime values. Note that
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some rarely used SAS date formats may be unsupported.
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blank_missing : boolean, defaults to True
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Convert empty strings to missing values (SAS uses blanks to
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indicate missing character variables).
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chunksize : int, defaults to None
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Return SAS7BDATReader object for iterations, returns chunks
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with given number of lines.
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encoding : string, defaults to None
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String encoding.
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convert_text : bool, defaults to True
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If False, text variables are left as raw bytes.
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convert_header_text : bool, defaults to True
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If False, header text, including column names, are left as raw
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bytes.
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"""
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def __init__(
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self,
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path_or_buf,
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index=None,
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convert_dates=True,
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blank_missing=True,
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chunksize=None,
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encoding=None,
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convert_text=True,
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convert_header_text=True,
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):
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self.index = index
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self.convert_dates = convert_dates
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self.blank_missing = blank_missing
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self.chunksize = chunksize
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self.encoding = encoding
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self.convert_text = convert_text
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self.convert_header_text = convert_header_text
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self.default_encoding = "latin-1"
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self.compression = ""
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self.column_names_strings = []
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self.column_names = []
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self.column_formats = []
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self.columns = []
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self._current_page_data_subheader_pointers = []
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self._cached_page = None
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self._column_data_lengths = []
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self._column_data_offsets = []
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self._column_types = []
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self._current_row_in_file_index = 0
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self._current_row_on_page_index = 0
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self._current_row_in_file_index = 0
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self._path_or_buf, _, _, _ = get_filepath_or_buffer(path_or_buf)
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if isinstance(self._path_or_buf, str):
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self._path_or_buf = open(self._path_or_buf, "rb")
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self.handle = self._path_or_buf
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self._get_properties()
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self._parse_metadata()
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def column_data_lengths(self):
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"""Return a numpy int64 array of the column data lengths"""
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return np.asarray(self._column_data_lengths, dtype=np.int64)
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def column_data_offsets(self):
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"""Return a numpy int64 array of the column offsets"""
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return np.asarray(self._column_data_offsets, dtype=np.int64)
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def column_types(self):
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"""
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Returns a numpy character array of the column types:
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s (string) or d (double)
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"""
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return np.asarray(self._column_types, dtype=np.dtype("S1"))
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def close(self):
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try:
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self.handle.close()
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except AttributeError:
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pass
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def _get_properties(self):
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# Check magic number
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self._path_or_buf.seek(0)
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self._cached_page = self._path_or_buf.read(288)
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if self._cached_page[0 : len(const.magic)] != const.magic:
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self.close()
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raise ValueError("magic number mismatch (not a SAS file?)")
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# Get alignment information
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align1, align2 = 0, 0
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buf = self._read_bytes(const.align_1_offset, const.align_1_length)
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if buf == const.u64_byte_checker_value:
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align2 = const.align_2_value
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self.U64 = True
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self._int_length = 8
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self._page_bit_offset = const.page_bit_offset_x64
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self._subheader_pointer_length = const.subheader_pointer_length_x64
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else:
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self.U64 = False
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self._page_bit_offset = const.page_bit_offset_x86
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self._subheader_pointer_length = const.subheader_pointer_length_x86
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self._int_length = 4
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buf = self._read_bytes(const.align_2_offset, const.align_2_length)
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if buf == const.align_1_checker_value:
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align1 = const.align_2_value
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total_align = align1 + align2
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# Get endianness information
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buf = self._read_bytes(const.endianness_offset, const.endianness_length)
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if buf == b"\x01":
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self.byte_order = "<"
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else:
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self.byte_order = ">"
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# Get encoding information
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buf = self._read_bytes(const.encoding_offset, const.encoding_length)[0]
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if buf in const.encoding_names:
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self.file_encoding = const.encoding_names[buf]
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else:
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self.file_encoding = f"unknown (code={buf})"
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# Get platform information
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buf = self._read_bytes(const.platform_offset, const.platform_length)
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if buf == b"1":
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self.platform = "unix"
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elif buf == b"2":
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self.platform = "windows"
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else:
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self.platform = "unknown"
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buf = self._read_bytes(const.dataset_offset, const.dataset_length)
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self.name = buf.rstrip(b"\x00 ")
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if self.convert_header_text:
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self.name = self.name.decode(self.encoding or self.default_encoding)
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buf = self._read_bytes(const.file_type_offset, const.file_type_length)
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self.file_type = buf.rstrip(b"\x00 ")
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if self.convert_header_text:
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self.file_type = self.file_type.decode(
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self.encoding or self.default_encoding
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)
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# Timestamp is epoch 01/01/1960
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epoch = datetime(1960, 1, 1)
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x = self._read_float(
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const.date_created_offset + align1, const.date_created_length
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)
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self.date_created = epoch + pd.to_timedelta(x, unit="s")
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x = self._read_float(
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const.date_modified_offset + align1, const.date_modified_length
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)
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self.date_modified = epoch + pd.to_timedelta(x, unit="s")
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self.header_length = self._read_int(
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const.header_size_offset + align1, const.header_size_length
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)
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# Read the rest of the header into cached_page.
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buf = self._path_or_buf.read(self.header_length - 288)
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self._cached_page += buf
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if len(self._cached_page) != self.header_length:
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self.close()
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raise ValueError("The SAS7BDAT file appears to be truncated.")
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self._page_length = self._read_int(
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const.page_size_offset + align1, const.page_size_length
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)
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self._page_count = self._read_int(
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const.page_count_offset + align1, const.page_count_length
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)
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buf = self._read_bytes(
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const.sas_release_offset + total_align, const.sas_release_length
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)
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self.sas_release = buf.rstrip(b"\x00 ")
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if self.convert_header_text:
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self.sas_release = self.sas_release.decode(
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self.encoding or self.default_encoding
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)
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buf = self._read_bytes(
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const.sas_server_type_offset + total_align, const.sas_server_type_length
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)
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self.server_type = buf.rstrip(b"\x00 ")
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if self.convert_header_text:
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self.server_type = self.server_type.decode(
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self.encoding or self.default_encoding
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)
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buf = self._read_bytes(
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const.os_version_number_offset + total_align, const.os_version_number_length
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)
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self.os_version = buf.rstrip(b"\x00 ")
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if self.convert_header_text:
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self.os_version = self.os_version.decode(
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self.encoding or self.default_encoding
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)
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buf = self._read_bytes(const.os_name_offset + total_align, const.os_name_length)
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buf = buf.rstrip(b"\x00 ")
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if len(buf) > 0:
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self.os_name = buf.decode(self.encoding or self.default_encoding)
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else:
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buf = self._read_bytes(
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const.os_maker_offset + total_align, const.os_maker_length
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)
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self.os_name = buf.rstrip(b"\x00 ")
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if self.convert_header_text:
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self.os_name = self.os_name.decode(
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self.encoding or self.default_encoding
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)
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def __next__(self):
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da = self.read(nrows=self.chunksize or 1)
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if da is None:
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raise StopIteration
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return da
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# Read a single float of the given width (4 or 8).
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def _read_float(self, offset, width):
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if width not in (4, 8):
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self.close()
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raise ValueError("invalid float width")
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buf = self._read_bytes(offset, width)
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fd = "f" if width == 4 else "d"
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return struct.unpack(self.byte_order + fd, buf)[0]
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# Read a single signed integer of the given width (1, 2, 4 or 8).
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def _read_int(self, offset, width):
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if width not in (1, 2, 4, 8):
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self.close()
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raise ValueError("invalid int width")
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buf = self._read_bytes(offset, width)
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it = {1: "b", 2: "h", 4: "l", 8: "q"}[width]
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iv = struct.unpack(self.byte_order + it, buf)[0]
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return iv
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def _read_bytes(self, offset, length):
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if self._cached_page is None:
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self._path_or_buf.seek(offset)
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buf = self._path_or_buf.read(length)
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if len(buf) < length:
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self.close()
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msg = f"Unable to read {length:d} bytes from file position {offset:d}."
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raise ValueError(msg)
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return buf
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else:
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if offset + length > len(self._cached_page):
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self.close()
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raise ValueError("The cached page is too small.")
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return self._cached_page[offset : offset + length]
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def _parse_metadata(self):
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done = False
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while not done:
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self._cached_page = self._path_or_buf.read(self._page_length)
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if len(self._cached_page) <= 0:
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break
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if len(self._cached_page) != self._page_length:
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self.close()
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raise ValueError("Failed to read a meta data page from the SAS file.")
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done = self._process_page_meta()
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def _process_page_meta(self):
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self._read_page_header()
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pt = [const.page_meta_type, const.page_amd_type] + const.page_mix_types
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if self._current_page_type in pt:
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self._process_page_metadata()
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is_data_page = self._current_page_type & const.page_data_type
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is_mix_page = self._current_page_type in const.page_mix_types
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return (
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is_data_page
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or is_mix_page
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or self._current_page_data_subheader_pointers != []
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)
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|
|
def _read_page_header(self):
|
||
|
|
bit_offset = self._page_bit_offset
|
||
|
|
tx = const.page_type_offset + bit_offset
|
||
|
|
self._current_page_type = self._read_int(tx, const.page_type_length)
|
||
|
|
tx = const.block_count_offset + bit_offset
|
||
|
|
self._current_page_block_count = self._read_int(tx, const.block_count_length)
|
||
|
|
tx = const.subheader_count_offset + bit_offset
|
||
|
|
self._current_page_subheaders_count = self._read_int(
|
||
|
|
tx, const.subheader_count_length
|
||
|
|
)
|
||
|
|
|
||
|
|
def _process_page_metadata(self):
|
||
|
|
bit_offset = self._page_bit_offset
|
||
|
|
|
||
|
|
for i in range(self._current_page_subheaders_count):
|
||
|
|
pointer = self._process_subheader_pointers(
|
||
|
|
const.subheader_pointers_offset + bit_offset, i
|
||
|
|
)
|
||
|
|
if pointer.length == 0:
|
||
|
|
continue
|
||
|
|
if pointer.compression == const.truncated_subheader_id:
|
||
|
|
continue
|
||
|
|
subheader_signature = self._read_subheader_signature(pointer.offset)
|
||
|
|
subheader_index = self._get_subheader_index(
|
||
|
|
subheader_signature, pointer.compression, pointer.ptype
|
||
|
|
)
|
||
|
|
self._process_subheader(subheader_index, pointer)
|
||
|
|
|
||
|
|
def _get_subheader_index(self, signature, compression, ptype):
|
||
|
|
index = const.subheader_signature_to_index.get(signature)
|
||
|
|
if index is None:
|
||
|
|
f1 = (compression == const.compressed_subheader_id) or (compression == 0)
|
||
|
|
f2 = ptype == const.compressed_subheader_type
|
||
|
|
if (self.compression != "") and f1 and f2:
|
||
|
|
index = const.SASIndex.data_subheader_index
|
||
|
|
else:
|
||
|
|
self.close()
|
||
|
|
raise ValueError("Unknown subheader signature")
|
||
|
|
return index
|
||
|
|
|
||
|
|
def _process_subheader_pointers(self, offset, subheader_pointer_index):
|
||
|
|
|
||
|
|
subheader_pointer_length = self._subheader_pointer_length
|
||
|
|
total_offset = offset + subheader_pointer_length * subheader_pointer_index
|
||
|
|
|
||
|
|
subheader_offset = self._read_int(total_offset, self._int_length)
|
||
|
|
total_offset += self._int_length
|
||
|
|
|
||
|
|
subheader_length = self._read_int(total_offset, self._int_length)
|
||
|
|
total_offset += self._int_length
|
||
|
|
|
||
|
|
subheader_compression = self._read_int(total_offset, 1)
|
||
|
|
total_offset += 1
|
||
|
|
|
||
|
|
subheader_type = self._read_int(total_offset, 1)
|
||
|
|
|
||
|
|
x = _subheader_pointer()
|
||
|
|
x.offset = subheader_offset
|
||
|
|
x.length = subheader_length
|
||
|
|
x.compression = subheader_compression
|
||
|
|
x.ptype = subheader_type
|
||
|
|
|
||
|
|
return x
|
||
|
|
|
||
|
|
def _read_subheader_signature(self, offset):
|
||
|
|
subheader_signature = self._read_bytes(offset, self._int_length)
|
||
|
|
return subheader_signature
|
||
|
|
|
||
|
|
def _process_subheader(self, subheader_index, pointer):
|
||
|
|
offset = pointer.offset
|
||
|
|
length = pointer.length
|
||
|
|
|
||
|
|
if subheader_index == const.SASIndex.row_size_index:
|
||
|
|
processor = self._process_rowsize_subheader
|
||
|
|
elif subheader_index == const.SASIndex.column_size_index:
|
||
|
|
processor = self._process_columnsize_subheader
|
||
|
|
elif subheader_index == const.SASIndex.column_text_index:
|
||
|
|
processor = self._process_columntext_subheader
|
||
|
|
elif subheader_index == const.SASIndex.column_name_index:
|
||
|
|
processor = self._process_columnname_subheader
|
||
|
|
elif subheader_index == const.SASIndex.column_attributes_index:
|
||
|
|
processor = self._process_columnattributes_subheader
|
||
|
|
elif subheader_index == const.SASIndex.format_and_label_index:
|
||
|
|
processor = self._process_format_subheader
|
||
|
|
elif subheader_index == const.SASIndex.column_list_index:
|
||
|
|
processor = self._process_columnlist_subheader
|
||
|
|
elif subheader_index == const.SASIndex.subheader_counts_index:
|
||
|
|
processor = self._process_subheader_counts
|
||
|
|
elif subheader_index == const.SASIndex.data_subheader_index:
|
||
|
|
self._current_page_data_subheader_pointers.append(pointer)
|
||
|
|
return
|
||
|
|
else:
|
||
|
|
raise ValueError("unknown subheader index")
|
||
|
|
|
||
|
|
processor(offset, length)
|
||
|
|
|
||
|
|
def _process_rowsize_subheader(self, offset, length):
|
||
|
|
|
||
|
|
int_len = self._int_length
|
||
|
|
lcs_offset = offset
|
||
|
|
lcp_offset = offset
|
||
|
|
if self.U64:
|
||
|
|
lcs_offset += 682
|
||
|
|
lcp_offset += 706
|
||
|
|
else:
|
||
|
|
lcs_offset += 354
|
||
|
|
lcp_offset += 378
|
||
|
|
|
||
|
|
self.row_length = self._read_int(
|
||
|
|
offset + const.row_length_offset_multiplier * int_len, int_len
|
||
|
|
)
|
||
|
|
self.row_count = self._read_int(
|
||
|
|
offset + const.row_count_offset_multiplier * int_len, int_len
|
||
|
|
)
|
||
|
|
self.col_count_p1 = self._read_int(
|
||
|
|
offset + const.col_count_p1_multiplier * int_len, int_len
|
||
|
|
)
|
||
|
|
self.col_count_p2 = self._read_int(
|
||
|
|
offset + const.col_count_p2_multiplier * int_len, int_len
|
||
|
|
)
|
||
|
|
mx = const.row_count_on_mix_page_offset_multiplier * int_len
|
||
|
|
self._mix_page_row_count = self._read_int(offset + mx, int_len)
|
||
|
|
self._lcs = self._read_int(lcs_offset, 2)
|
||
|
|
self._lcp = self._read_int(lcp_offset, 2)
|
||
|
|
|
||
|
|
def _process_columnsize_subheader(self, offset, length):
|
||
|
|
int_len = self._int_length
|
||
|
|
offset += int_len
|
||
|
|
self.column_count = self._read_int(offset, int_len)
|
||
|
|
if self.col_count_p1 + self.col_count_p2 != self.column_count:
|
||
|
|
print(
|
||
|
|
f"Warning: column count mismatch ({self.col_count_p1} + "
|
||
|
|
f"{self.col_count_p2} != {self.column_count})\n"
|
||
|
|
)
|
||
|
|
|
||
|
|
# Unknown purpose
|
||
|
|
def _process_subheader_counts(self, offset, length):
|
||
|
|
pass
|
||
|
|
|
||
|
|
def _process_columntext_subheader(self, offset, length):
|
||
|
|
|
||
|
|
offset += self._int_length
|
||
|
|
text_block_size = self._read_int(offset, const.text_block_size_length)
|
||
|
|
|
||
|
|
buf = self._read_bytes(offset, text_block_size)
|
||
|
|
cname_raw = buf[0:text_block_size].rstrip(b"\x00 ")
|
||
|
|
cname = cname_raw
|
||
|
|
if self.convert_header_text:
|
||
|
|
cname = cname.decode(self.encoding or self.default_encoding)
|
||
|
|
self.column_names_strings.append(cname)
|
||
|
|
|
||
|
|
if len(self.column_names_strings) == 1:
|
||
|
|
compression_literal = ""
|
||
|
|
for cl in const.compression_literals:
|
||
|
|
if cl in cname_raw:
|
||
|
|
compression_literal = cl
|
||
|
|
self.compression = compression_literal
|
||
|
|
offset -= self._int_length
|
||
|
|
|
||
|
|
offset1 = offset + 16
|
||
|
|
if self.U64:
|
||
|
|
offset1 += 4
|
||
|
|
|
||
|
|
buf = self._read_bytes(offset1, self._lcp)
|
||
|
|
compression_literal = buf.rstrip(b"\x00")
|
||
|
|
if compression_literal == "":
|
||
|
|
self._lcs = 0
|
||
|
|
offset1 = offset + 32
|
||
|
|
if self.U64:
|
||
|
|
offset1 += 4
|
||
|
|
buf = self._read_bytes(offset1, self._lcp)
|
||
|
|
self.creator_proc = buf[0 : self._lcp]
|
||
|
|
elif compression_literal == const.rle_compression:
|
||
|
|
offset1 = offset + 40
|
||
|
|
if self.U64:
|
||
|
|
offset1 += 4
|
||
|
|
buf = self._read_bytes(offset1, self._lcp)
|
||
|
|
self.creator_proc = buf[0 : self._lcp]
|
||
|
|
elif self._lcs > 0:
|
||
|
|
self._lcp = 0
|
||
|
|
offset1 = offset + 16
|
||
|
|
if self.U64:
|
||
|
|
offset1 += 4
|
||
|
|
buf = self._read_bytes(offset1, self._lcs)
|
||
|
|
self.creator_proc = buf[0 : self._lcp]
|
||
|
|
if self.convert_header_text:
|
||
|
|
if hasattr(self, "creator_proc"):
|
||
|
|
self.creator_proc = self.creator_proc.decode(
|
||
|
|
self.encoding or self.default_encoding
|
||
|
|
)
|
||
|
|
|
||
|
|
def _process_columnname_subheader(self, offset, length):
|
||
|
|
int_len = self._int_length
|
||
|
|
offset += int_len
|
||
|
|
column_name_pointers_count = (length - 2 * int_len - 12) // 8
|
||
|
|
for i in range(column_name_pointers_count):
|
||
|
|
text_subheader = (
|
||
|
|
offset
|
||
|
|
+ const.column_name_pointer_length * (i + 1)
|
||
|
|
+ const.column_name_text_subheader_offset
|
||
|
|
)
|
||
|
|
col_name_offset = (
|
||
|
|
offset
|
||
|
|
+ const.column_name_pointer_length * (i + 1)
|
||
|
|
+ const.column_name_offset_offset
|
||
|
|
)
|
||
|
|
col_name_length = (
|
||
|
|
offset
|
||
|
|
+ const.column_name_pointer_length * (i + 1)
|
||
|
|
+ const.column_name_length_offset
|
||
|
|
)
|
||
|
|
|
||
|
|
idx = self._read_int(
|
||
|
|
text_subheader, const.column_name_text_subheader_length
|
||
|
|
)
|
||
|
|
col_offset = self._read_int(
|
||
|
|
col_name_offset, const.column_name_offset_length
|
||
|
|
)
|
||
|
|
col_len = self._read_int(col_name_length, const.column_name_length_length)
|
||
|
|
|
||
|
|
name_str = self.column_names_strings[idx]
|
||
|
|
self.column_names.append(name_str[col_offset : col_offset + col_len])
|
||
|
|
|
||
|
|
def _process_columnattributes_subheader(self, offset, length):
|
||
|
|
int_len = self._int_length
|
||
|
|
column_attributes_vectors_count = (length - 2 * int_len - 12) // (int_len + 8)
|
||
|
|
for i in range(column_attributes_vectors_count):
|
||
|
|
col_data_offset = (
|
||
|
|
offset + int_len + const.column_data_offset_offset + i * (int_len + 8)
|
||
|
|
)
|
||
|
|
col_data_len = (
|
||
|
|
offset
|
||
|
|
+ 2 * int_len
|
||
|
|
+ const.column_data_length_offset
|
||
|
|
+ i * (int_len + 8)
|
||
|
|
)
|
||
|
|
col_types = (
|
||
|
|
offset + 2 * int_len + const.column_type_offset + i * (int_len + 8)
|
||
|
|
)
|
||
|
|
|
||
|
|
x = self._read_int(col_data_offset, int_len)
|
||
|
|
self._column_data_offsets.append(x)
|
||
|
|
|
||
|
|
x = self._read_int(col_data_len, const.column_data_length_length)
|
||
|
|
self._column_data_lengths.append(x)
|
||
|
|
|
||
|
|
x = self._read_int(col_types, const.column_type_length)
|
||
|
|
self._column_types.append(b"d" if x == 1 else b"s")
|
||
|
|
|
||
|
|
def _process_columnlist_subheader(self, offset, length):
|
||
|
|
# unknown purpose
|
||
|
|
pass
|
||
|
|
|
||
|
|
def _process_format_subheader(self, offset, length):
|
||
|
|
int_len = self._int_length
|
||
|
|
text_subheader_format = (
|
||
|
|
offset + const.column_format_text_subheader_index_offset + 3 * int_len
|
||
|
|
)
|
||
|
|
col_format_offset = offset + const.column_format_offset_offset + 3 * int_len
|
||
|
|
col_format_len = offset + const.column_format_length_offset + 3 * int_len
|
||
|
|
text_subheader_label = (
|
||
|
|
offset + const.column_label_text_subheader_index_offset + 3 * int_len
|
||
|
|
)
|
||
|
|
col_label_offset = offset + const.column_label_offset_offset + 3 * int_len
|
||
|
|
col_label_len = offset + const.column_label_length_offset + 3 * int_len
|
||
|
|
|
||
|
|
x = self._read_int(
|
||
|
|
text_subheader_format, const.column_format_text_subheader_index_length
|
||
|
|
)
|
||
|
|
format_idx = min(x, len(self.column_names_strings) - 1)
|
||
|
|
|
||
|
|
format_start = self._read_int(
|
||
|
|
col_format_offset, const.column_format_offset_length
|
||
|
|
)
|
||
|
|
format_len = self._read_int(col_format_len, const.column_format_length_length)
|
||
|
|
|
||
|
|
label_idx = self._read_int(
|
||
|
|
text_subheader_label, const.column_label_text_subheader_index_length
|
||
|
|
)
|
||
|
|
label_idx = min(label_idx, len(self.column_names_strings) - 1)
|
||
|
|
|
||
|
|
label_start = self._read_int(col_label_offset, const.column_label_offset_length)
|
||
|
|
label_len = self._read_int(col_label_len, const.column_label_length_length)
|
||
|
|
|
||
|
|
label_names = self.column_names_strings[label_idx]
|
||
|
|
column_label = label_names[label_start : label_start + label_len]
|
||
|
|
format_names = self.column_names_strings[format_idx]
|
||
|
|
column_format = format_names[format_start : format_start + format_len]
|
||
|
|
current_column_number = len(self.columns)
|
||
|
|
|
||
|
|
col = _column()
|
||
|
|
col.col_id = current_column_number
|
||
|
|
col.name = self.column_names[current_column_number]
|
||
|
|
col.label = column_label
|
||
|
|
col.format = column_format
|
||
|
|
col.ctype = self._column_types[current_column_number]
|
||
|
|
col.length = self._column_data_lengths[current_column_number]
|
||
|
|
|
||
|
|
self.column_formats.append(column_format)
|
||
|
|
self.columns.append(col)
|
||
|
|
|
||
|
|
def read(self, nrows=None):
|
||
|
|
|
||
|
|
if (nrows is None) and (self.chunksize is not None):
|
||
|
|
nrows = self.chunksize
|
||
|
|
elif nrows is None:
|
||
|
|
nrows = self.row_count
|
||
|
|
|
||
|
|
if len(self._column_types) == 0:
|
||
|
|
self.close()
|
||
|
|
raise EmptyDataError("No columns to parse from file")
|
||
|
|
|
||
|
|
if self._current_row_in_file_index >= self.row_count:
|
||
|
|
return None
|
||
|
|
|
||
|
|
m = self.row_count - self._current_row_in_file_index
|
||
|
|
if nrows > m:
|
||
|
|
nrows = m
|
||
|
|
|
||
|
|
nd = self._column_types.count(b"d")
|
||
|
|
ns = self._column_types.count(b"s")
|
||
|
|
|
||
|
|
self._string_chunk = np.empty((ns, nrows), dtype=object)
|
||
|
|
self._byte_chunk = np.zeros((nd, 8 * nrows), dtype=np.uint8)
|
||
|
|
|
||
|
|
self._current_row_in_chunk_index = 0
|
||
|
|
p = Parser(self)
|
||
|
|
p.read(nrows)
|
||
|
|
|
||
|
|
rslt = self._chunk_to_dataframe()
|
||
|
|
if self.index is not None:
|
||
|
|
rslt = rslt.set_index(self.index)
|
||
|
|
|
||
|
|
return rslt
|
||
|
|
|
||
|
|
def _read_next_page(self):
|
||
|
|
self._current_page_data_subheader_pointers = []
|
||
|
|
self._cached_page = self._path_or_buf.read(self._page_length)
|
||
|
|
if len(self._cached_page) <= 0:
|
||
|
|
return True
|
||
|
|
elif len(self._cached_page) != self._page_length:
|
||
|
|
self.close()
|
||
|
|
msg = (
|
||
|
|
"failed to read complete page from file (read "
|
||
|
|
f"{len(self._cached_page):d} of {self._page_length:d} bytes)"
|
||
|
|
)
|
||
|
|
raise ValueError(msg)
|
||
|
|
|
||
|
|
self._read_page_header()
|
||
|
|
page_type = self._current_page_type
|
||
|
|
if page_type == const.page_meta_type:
|
||
|
|
self._process_page_metadata()
|
||
|
|
|
||
|
|
is_data_page = page_type & const.page_data_type
|
||
|
|
pt = [const.page_meta_type] + const.page_mix_types
|
||
|
|
if not is_data_page and self._current_page_type not in pt:
|
||
|
|
return self._read_next_page()
|
||
|
|
|
||
|
|
return False
|
||
|
|
|
||
|
|
def _chunk_to_dataframe(self):
|
||
|
|
|
||
|
|
n = self._current_row_in_chunk_index
|
||
|
|
m = self._current_row_in_file_index
|
||
|
|
ix = range(m - n, m)
|
||
|
|
rslt = pd.DataFrame(index=ix)
|
||
|
|
|
||
|
|
js, jb = 0, 0
|
||
|
|
for j in range(self.column_count):
|
||
|
|
|
||
|
|
name = self.column_names[j]
|
||
|
|
|
||
|
|
if self._column_types[j] == b"d":
|
||
|
|
rslt[name] = self._byte_chunk[jb, :].view(dtype=self.byte_order + "d")
|
||
|
|
rslt[name] = np.asarray(rslt[name], dtype=np.float64)
|
||
|
|
if self.convert_dates:
|
||
|
|
if self.column_formats[j] in const.sas_date_formats:
|
||
|
|
rslt[name] = _convert_datetimes(rslt[name], "d")
|
||
|
|
elif self.column_formats[j] in const.sas_datetime_formats:
|
||
|
|
rslt[name] = _convert_datetimes(rslt[name], "s")
|
||
|
|
jb += 1
|
||
|
|
elif self._column_types[j] == b"s":
|
||
|
|
rslt[name] = self._string_chunk[js, :]
|
||
|
|
if self.convert_text and (self.encoding is not None):
|
||
|
|
rslt[name] = rslt[name].str.decode(
|
||
|
|
self.encoding or self.default_encoding
|
||
|
|
)
|
||
|
|
if self.blank_missing:
|
||
|
|
ii = rslt[name].str.len() == 0
|
||
|
|
rslt.loc[ii, name] = np.nan
|
||
|
|
js += 1
|
||
|
|
else:
|
||
|
|
self.close()
|
||
|
|
raise ValueError(f"unknown column type {self._column_types[j]}")
|
||
|
|
|
||
|
|
return rslt
|