KeyError: 'nsamples'

[gsleap]

When reading a filterbank file which already has nsamples populated, I get a KeyError exception as it appears that sigpyproc3 wants to calculate this value?
see:

sigpyproc3/sigpyproc/io/sigproc.py

Lines 288 to 290 in 968f89d

	header["nsamples"] = (
	8 * int(header["datalen"]) // int(header["nbits"]) // int(header["nchans"])
	)

nsamples isn't in the list of valid keyword:

sigpyproc3/sigpyproc/io/sigproc.py

Lines 18 to 42 in 968f89d

	header_keys = {
	"signed": "b",
	"telescope_id": "I",
	"ibeam": "I",
	"nbeams": "I",
	"refdm": "d",
	"nifs": "I",
	"nchans": "I",
	"foff": "d",
	"fch1": "d",
	"nbits": "I",
	"tsamp": "d",
	"tstart": "d",
	"src_dej": "d",
	"src_raj": "d",
	"za_start": "d",
	"az_start": "d",
	"source_name": "str",
	"rawdatafile": "str",
	"data_type": "I",
	"machine_id": "I",
	"barycentric": "I",
	"pulsarcentric": "I",
	}
	"""Header keys recognised by the sigproc package."""

I think that if nsamples is provided by the filterbank file (as it is a valid keyword), it should either be ignored (maybe with a warning?) and the calculated value used, or should be read/used instead of the calculated value.

Example of error message:

$ spp_header print my_test_file.fil
Traceback (most recent call last):
  File "/home/gsleap/work/github/sigpyproc3/.venv/bin/spp_header", line 10, in <module>
    sys.exit(main())
             ^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/.venv/lib/python3.12/site-packages/rich_click/rich_command.py", line 402, in __call__
    return super().__call__(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/.venv/lib/python3.12/site-packages/click/core.py", line 1485, in __call__
    return self.main(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/.venv/lib/python3.12/site-packages/rich_click/rich_command.py", line 216, in main
    rv = self.invoke(ctx)
         ^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/.venv/lib/python3.12/site-packages/click/core.py", line 1873, in invoke
    return _process_result(sub_ctx.command.invoke(sub_ctx))
                           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/.venv/lib/python3.12/site-packages/click/core.py", line 1269, in invoke
    return ctx.invoke(self.callback, **ctx.params)
           ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/.venv/lib/python3.12/site-packages/click/core.py", line 824, in invoke
    return callback(*args, **kwargs)
           ^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/sigpyproc/apps/spp_header.py", line 54, in print
    header = hdr_reader(filename)
             ^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/sigpyproc/header.py", line 710, in from_sigproc
    header = sigproc.parse_header_multi(
             ^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/sigpyproc/io/sigproc.py", line 225, in parse_header_multi
    header = parse_header(filenames[0])
             ^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/home/gsleap/work/github/sigpyproc3/sigpyproc/io/sigproc.py", line 283, in parse_header
    key_fmt = header_keys[key]
              ~~~~~~~~~~~^^^^^
KeyError: 'nsamples'

[pravirkr]

Thanks for raising this. Solving this in #56.

• sigproc header parsing should skip invalid keywords (only warning, no error).
• nsamples is added to valid keywords (read-only). At runtime, we choose the minimum of the two (file size and metadata) with a warning.
• Since it's a legacy keyword (as per sigproc original documentation), sigpyproc will only support reading and not writing.

[gsleap]

Thanks @pravirkr!