funcolumnactivate(3)

NAME
FunColumnActivate - activate Funtools columns

SYNOPSIS
  #include <funtools.h>

  void FunColumnActivate(Fun fun, char *s, char *plist)

DESCRIPTION
The FunColumnActivate() routine determines which columns (set up by FunColumnSelect()) ultimately will be read and/or written. By default, all columns that are selected using FunColumnSelect() are activated. The FunColumnActivate() routine can be used to turn off/off activation of specific columns.

The first argument is the Fun handle associated with this set of columns. The second argument is a space-delimited list of columns to activate or de-activate. Columns preceded by "+" are activated and columns preceded by a "-" are de-activated. If a column is named without "+" or "-", it is activated. The reserved strings "$region" and '$n' are used to activate a special columns containing the filter region value and row value, respectively, associated with this row. For example, if a filter containing two circular regions is specified as part of the Funtools file name, this column will contain a value of 1 or 2, depending on which region that row was in. The reserved strings "$x" and "$y" are used to activate the current binning columns. Thus, if the columns DX and DY are specified as binning columns:

  [sh $] fundisp foo.fits[bincols=(DX,DY)]

then "$x" and "$y" will refer to these columns in a call to FunColumnActivate().

In addition, if the activation string contains only columns to be activated, then the routine will de-activate all other columns. Similarly, if the activation string contains only columns to de-activate, then the routine will activate all other columns before activating the list. This makes it simple to change the activation state of all columns without having to know all of the column names. For example:

•   "pi pha time" # only these three columns will be active

•   "-pi -pha -time" # all but these columns will be active

•   "pi -pha" # only pi is active, pha is not, others are not

•   "+pi -pha" # same as above

•   "pi -pha -time" # only pi is active, all others are not

•   "pi pha" # pha and pi are active, all others are not

•   "pi pha -x -y" # pha and pi are active, all others are not

You can use the column activation list to reorder columns, since columns are output in the order specified. For example:

  # default output order
  fundisp snr.ev'[cir 512 512 .1]'
         X        Y      PHA       PI                  TIME       DX       DY
  -------- -------- -------- -------- --------------------- -------- --------
       512      512        6        7     79493997.45854475      578      574
       512      512        8        9     79494575.58943175      579      573
       512      512        5        6     79493631.03866175      578      575
       512      512        5        5     79493290.86521725      578      575
       512      512        8        9     79493432.00990875      579      573

  # re-order the output by specifying explicit order
  fundisp snr.ev'[cir 512 512 .1]' "time x y dy dx pi pha"
                   TIME        X        Y       DY       DX       PI      PHA
  --------------------- -------- -------- -------- -------- -------- --------
      79493997.45854475      512      512      574      578        7        6
      79494575.58943175      512      512      573      579        9        8
      79493631.03866175      512      512      575      578        6        5
      79493290.86521725      512      512      575      578        5        5
      79493432.00990875      512      512      573      579        9        8

A "+" sign by itself means to activate all columns, so that you can reorder just a few columns without specifying all of them:

  # reorder 3 columns and then output the rest
  fundisp snr.ev'[cir 512 512 .1]' "time pi pha +"
                   TIME       PI      PHA        Y        X       DX       DY
  --------------------- -------- -------- -------- -------- -------- --------
      79493997.45854475        7        6      512      512      578      574
      79494575.58943175        9        8      512      512      579      573
      79493631.03866175        6        5      512      512      578      575
      79493290.86521725        5        5      512      512      578      575
      79493432.00990875        9        8      512      512      579      573

The column activation/deactivation is performed in the order of the specified column arguments. This means you can mix "+", "-" (which de-activates all columns) and specific column names to reorder and select columns in one command. For example, consider the following:

  # reorder and de-activate
  fundisp snr.ev'[cir 512 512 .1]' "time pi pha + -x -y"
                   TIME       PI      PHA       DX       DY
  --------------------- -------- -------- -------- --------
      79493997.45854475        7        6      578      574
      79494575.58943175        9        8      579      573
      79493631.03866175        6        5      578      575
      79493290.86521725        5        5      578      575
      79493432.00990875        9        8      579      573

We first activate "time", "pi", and "pha" so that they are output first. We then activate all of the other columns, and then de-activate "x" and "y". Note that this is different from:

  # probably not what you want ...
  fundisp snr.ev'[cir 512 512 .1]' "time pi pha -x -y +"
                   TIME       PI      PHA        Y        X       DX       DY
  --------------------- -------- -------- -------- -------- -------- --------
      79493997.45854475        7        6      512      512      578      574
      79494575.58943175        9        8      512      512      579      573
      79493631.03866175        6        5      512      512      578      575
      79493290.86521725        5        5      512      512      578      575
      79493432.00990875        9        8      512      512      579      573

Here, "x" and "y" are de-activated, but then all columns including "x" and "y" are again re-activated.

Typically, FunColumnActivate() uses a list of columns that are passed into the program from the command line. For example, the code for funtable contains the following:

  char *cols=NULL;

  /* open the input FITS file */
  if( !(fun = FunOpen(argv[1], "rc", NULL)) )
    gerror(stderr, "could not FunOpen input file: %s\n", argv[1]);

  /* set active flag for specified columns */
  if( argc >= 4 ) cols = argv[3];
  FunColumnActivate(fun, cols, NULL);

The FunOpen() call sets the default columns to be all columns in the input file. The FunColumnActivate() call then allows the user to control which columns ultimately will be activated (i.e., in this case, written to the new file). For example:

  funtable test.ev foo.ev "pi pha time"

will process only the three columns mentioned, while:

  funtable test.ev foo.ev "-time"

will process all columns except "time".

If FunColumnActivate() is called with a null string, then the environment variable FUN_COLUMNS will be used to provide a global value, if present. This is the reason why we call the routine even if no columns are specified on the command line (see example above), instead of calling it this way:

  /* set active flag for specified columns */
  if( argc >= 4 ){
    FunColumnActivate(fun, argv[3], NULL);
  }

SEE ALSO
See funtools(7) for a list of Funtools help pages