def write_textual_reel_header(fh, lines, encoding):
"""Write the SEG Y card image header, also known as the textual header
Args:
fh: A file-like object open in binary mode positioned such that the
beginning of the textual header will be the next byte to read.
lines: An iterable series of forty lines, each of which must be a
Unicode string of CARD_LENGTH characters. The first three characters
of each line are often "C 1" to "C40" (as required by the SEG Y
standard) although this is not enforced by this function, since
many widespread SEG Y readers and writers do not adhere to this
constraint. To produce a SEG Y compliant series of header lines
consider using the format_standard_textual_header() function.
Any lines longer than CARD_LENGTH characters will be truncated without
warning. Any excess lines over CARDS_PER_HEADER will be discarded. Short
or omitted lines will be padded with spaces.
encoding: Typically 'cp037' for EBCDIC or 'ascii' for ASCII.
Post-condition:
The file pointer in fh will be positioned at the first byte following the textual
header.
Raises:
UnsupportedEncodingError: If encoding is neither EBCDIC nor ASCII.
UnicodeError: If the data provided in lines cannot be encoded with the encoding.
"""
if not is_supported_encoding(encoding):
raise UnsupportedEncodingError("Writing textual reel header", encoding)
fh.seek(0)
padded_lines = [line.encode(encoding).ljust(CARD_LENGTH, ' '.encode(encoding))[:CARD_LENGTH]
for line in pad(lines, padding='', size=CARDS_PER_HEADER)]
joined_header = EMPTY_BYTE_STRING.join(padded_lines)
assert len(joined_header) == 3200
fh.write(joined_header)
fh.seek(TEXTUAL_HEADER_NUM_BYTES)
def write_textual_reel_header(fh, lines, encoding):
"""Write the SEG Y card image header, also known as the textual header
Args:
fh: A file-like object open in binary mode positioned such that the
beginning of the textual header will be the next byte to read.
lines: An iterable series of forty lines, each of which must be a
Unicode string of CARD_LENGTH characters. The first three characters
of each line are often "C 1" to "C40" (as required by the SEG Y
standard) although this is not enforced by this function, since
many widespread SEG Y readers and writers do not adhere to this
constraint. To produce a SEG Y compliant series of header lines
consider using the format_standard_textual_header() function.
Any lines longer than CARD_LENGTH characters will be truncated without
warning. Any excess lines over CARDS_PER_HEADER will be discarded. Short
or omitted lines will be padded with spaces.
encoding: Typically 'cp037' for EBCDIC or 'ascii' for ASCII.
Post-condition:
The file pointer in fh will be positioned at the first byte following the textual
header.
Raises:
UnsupportedEncodingError: If encoding is neither EBCDIC nor ASCII.
UnicodeError: If the data provided in lines cannot be encoded with the encoding.
"""
if not is_supported_encoding(encoding):
raise UnsupportedEncodingError("Writing textual reel header", encoding)
fh.seek(0)
padded_lines = [line.encode(encoding).ljust(CARD_LENGTH, ' '.encode(encoding))[:CARD_LENGTH]
for line in pad(lines, padding='', size=CARDS_PER_HEADER)]
joined_header = EMPTY_BYTE_STRING.join(padded_lines)
assert len(joined_header) == 3200
fh.write(joined_header)
fh.seek(TEXTUAL_HEADER_NUM_BYTES)