Disk Format

BTables are a binary file format on disk. In general, labels are written as a delimited sequence of 2-byte UTF-16 characters (joined with the ASCII unit separator, ASCII # 31), and all cell values are 8-byte doubles.

Table format:

• Integer format version (4 bytes). Currently 0.

• Integer character count of joined labels string, including delimiters (4 bytes)

  • Note: Label characters are 2-byte UTF-16 chars, meaning the raw bytecount is 2 * character count

• Label string as sequence of 2-byte UTF-16 characters

Then, for each row: - Integer number of nonzero values in row (4 bytes)

 - Sequential 'pairs' of index/value for each nonzero cell (4 bytes integer index, 8 byte double value)

All numeric values are written big-endian.

An example row sequence of:

[[38.2 0.0 0.0 47.3 0.0]
 [0.0 63.4 79.5 0.0 0.0]]

would be written to disk as:

2 0 38.2 3 47.3 2 1 63.4 2 79.6