replacecol
Usage:
replacecol [-name <name>] [-units <units>] [-ucd <ucd>]
[-utype <utype>] [-xtype <xtype>] [-desc <descrip>]
<col-id> <expr>
Replaces the content of a column with the value of an
algebraic expression.
The old values are discarded in favour of the result of
evaluating <expr>.
You can specify the metadata for the new column using the
-name, -units, -ucd,
-utype, -xtype
and -desc flags; for any of these items which you
do not specify, they will take the values from the column
being replaced.
It is legal to reference the replaced column in the
expression,
so for example "replacecol pixsize pixsize*2"
just multiplies the values in column pixsize by 2.
Syntax for the <col-id> and <expr> arguments is described in the manual.