godber
commented
9 years ago The possible data types for an image object are outlined in Chapter 3 of the PDS3 reference document:
https://pds.nasa.gov/documents/sr/Chapter03.pdf
Also, "Appendix C - Internal Representation of Data Types" is useful:
https://pds.nasa.gov/documents/sr/AppendixC.pdf
Below, I have extracted the data types valid for SAMPLE_TYPE, which is what image objects would use:
IBM_INTEGER IBM 360/370 mainframe 1-, 2-, and 4-byte signed integers
IBM_REAL IBM 360/370 mainframe real number (4- or 8-byte)
IBM_UNSIGNED_INTEGER IBM 360/370 mainframe 1-, 2-, and 4-byte unsigned integers
IEEE_REAL 4-, 8- and 10-byte real numbers
LSB_INTEGER 1-, 2-, and 4-byte signed integers
LSB_UNSIGNED_INTEGER 1-, 2-, and 4-byte unsigned integers
MAC_INTEGER alias for MSB_INTEGER
MAC_REAL alias for IEEE_REAL
MAC_UNSIGNED_INTEGER alias for MSB_UNSIGNED_INTEGER
MSB_INTEGER 1-, 2-, and 4-byte signed integers
MSB_UNSIGNED_INTEGER 1-, 2-, and 4-byte unsigned integers
PC_INTEGER alias for LSB_INTEGER
PC_REAL 4-, 8-, and 10-byte real numbers in IBM/PC format
PC_UNSIGNED_INTEGER alias for LSB_UNSIGNED_INTEGER
SUN_INTEGER alias for MSB_INTEGER
SUN_REAL alias for IEEE_REAL
SUN_UNSIGNED_INTEGER alias for MSB_UNSIGNED_INTEGER
VAX_DOUBLE alias for VAX_REAL
VAX_INTEGER alias for LSB_INTEGER
VAX_REAL Vax F-, D-, and H-type (4-, 8- and 16-byte, respectively) real numbers
VAX_UNSIGNED_INTEGER alias for LSB_UNSIGNED_INTEGER
VAXG_REAL Vax G-type (8-byte) real numbers
We only handle integer types. We should handle all valid types.
For example 32 bit float
PC_REALto support this:https://github.com/RyanBalfanz/PyPDS/issues/20
Also, the fact that we are using both a chain of if statements AND dictionary lookup seems a little redundant to me. I think the existing implementation can be changed to use nested dictionaries exclusively. Or at least nearly so.