./guide
get_scan_numbers.pro

Last modification date:

Wed Sep 28 13:27:09 2016

get_scan_numbers

function get_scan_numbers([count], [/keep], [/unique], [_EXTRA=extra keywords])

Function to return scan numbers for the input file.

This returns the different scan numbers in the order they appear in the input file. Use the keep flag to get the scan numbers from the output file. For example, if list shows these scan numbers: 99, 99, 99, 100, 99, 99, 100, 100, 101, 101, then get_scan_numbers will return this array [99, 100, 99, 100, 101]. If unique is set it will return this array [99, 100, 101].

The default behavior (without the unique flag set) is a useful check to see if a scan number repeats itself in a raw data file. That may cause processing problems since the standard calibration routines rely on scan numbers not appearing again later in the same data file. If you want to simply see which scan numbers appear in a data file where repeating scan numbers is expected or not otherwise a problem (e.g. an output file containing processed data), use the unique flag.

Selection fields can be used here in the same way that they can be used in other data selection procedures and functions. For a complete list of eligible parameters use the procedure listcols

See the discussion on "Select" in the User's Guide for a summary of selection syntax.

The selection criteria are ultimately passed to the io class's search_index via the _EXTRA parameter.

Returns

an array of scan numbers. Returns -1 (an illegal scan number) if the file is empty, or nothing matches the selection criteria.

Examples

    a = get_scan_numbers()
    print,a
    a = get_scan_numbers(source='3C*',/unique)
    print,a
 

Version

$Id$

Parameters
count out, optional variable	The number of scan numbers returned. This is 0 when no scan numbers are in the file (the returned value from this function will also be -1 in that case).

Keywords
keep in, optional boolean	If set, the scan numbers come from the output file.
unique in, optional boolean	If set, the unique scan numbers are returned. This is a sorted list and it is impossible to tell if there are any duplicate scan numbers.
_EXTRA in, optional extra keywords	These are the selection parameters.